Allergic rhinitis

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Allergic rhinitis
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• Rhinitis is defined as inflammation of the nasal
  membranes and is characterized by a symptom
  complex that consists of any combination of the
  following sneezing, nasal congestion, nasal
  itching, and rhinorrhea.
• The eyes, ears, sinuses, and throat can also be
  involved.
• Allergic rhinitis is very common cause of
  rhinitis.

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Pathophysiology

• Allergic rhinitis involves inflammation of the
  mucous membranes of the nose, eyes, eustachian
  tubes, middle ear, sinuses, and pharynx. The nose
  invariably is involved, and the other organs are
  affected in certain individuals.
• Inflammation of the mucous membranes is
  characterized by a complex interaction of
  inflammatory mediators but ultimately is
  triggered by an immunoglobulin E (IgE)mediated
  response to an extrinsic protein.

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• The tendency to develop allergic, or
  IgE-mediated, reactions to extrinsic allergens
  (proteins capable of causing an allergic
  reaction) has a genetic component.
• In susceptible individuals, exposure to certain
  foreign proteins leads to allergic sensitization,
  which is characterized by the production of
  specific IgE directed against these proteins.
• This specific IgE coats the surface of mast
  cells, which are present in the nasal mucosa.
• When the specific protein (eg, a specific pollen
  grain) is inhaled into the nose, it can bind to
  the IgE on the mast cells, leading to immediate
  and delayed release of a number of mediators.

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• The mediators that are immediately released
  include histamine, tryptase, chymase, kinins, and
  heparin.
• The mast cells quickly synthesize other
  mediators, including leukotrienes and
  prostaglandin D2.
• These mediators, via various interactions,
  ultimately lead to the symptoms of rhinorrhea
  (ie, nasal congestion, sneezing, itching,
  redness, tearing, swelling, ear pressure,
  postnasal drip).
• Mucous glands are stimulated, leading to
  increased secretions. Vascular permeability is
  increased, leading to plasma exudation.
• Vasodilation occurs, leading to congestion and
  pressure.
• Sensory nerves are stimulated, leading to
  sneezing and itching.
• All of these events can occur in minutes hence,
  this reaction is called the early, or immediate,
  phase of the reaction.

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• Over 4-8 hours, these mediators, through a
  complex interplay of events, lead to the
  recruitment of other inflammatory cells to the
  mucosa, such as neutrophils, eosinophils,
  lymphocytes, and macrophages.
• This results in continued inflammation, termed
  the late-phase response.
• The symptoms of the late-phase response are
  similar to those of the early phase, but less
  sneezing and itching and more congestion and
  mucus production tend to occur.
• The late phase may persist for hours or days.

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•          A number of complications that can lead
  to increased morbidity or even mortality can
  occur secondary to allergic rhinitis. Possible
  complications include otitis media, eustachian
  tube dysfunction, acute sinusitis, and chronic
  sinusitis.
•          Allergic rhinitis can be associated
  with a number of comorbid conditions, including
  asthma, atopic dermatitis, and nasal polyps.
  Evidence now suggests that uncontrolled allergic
  rhinitis can actually worsen the inflammation
  associated with asthma or atopic dermatitis. This
  could lead to further morbidity and even
  mortality.
•          Allergic rhinitis can frequently lead
  to significant impairment of quality of life.
  Symptoms such as fatigue, drowsiness (due to the
  disease or to medications), and malaise can lead
  to impaired work and school performance, missed
  school or work days, and traffic accidents. The
  overall cost (direct and indirect) of allergic
  rhinitis was recently estimated to be 5.3
  billion per year.

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History

• Symptoms and chronicity
• Trigger factors
• Response to treatment
• Comorbid conditions
• Family history
• Environmental and occupational exposure
• Effects on quality of life

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Symptoms and chronicity

• Determine the age of onset of symptoms and
  whether symptoms have been present continuously
  since onset. While the onset of allergic rhinitis
  can occur well into adulthood, most patients
  develop symptoms by age 20 years.
• Determine the time pattern of symptoms and
  whether symptoms occur at a consistent level
  throughout the year (ie, perennial rhinitis),
  only occur in specific seasons (ie, seasonal
  rhinitis), or a combination of the two. During
  periods of exacerbation, determine whether
  symptoms occur on a daily basis or only on an
  episodic basis. Determine whether the symptoms
  are present all day or only at specific times
  during the day.
• Determine which organ systems are affected and
  the specific symptoms. Some patients have
  exclusive involvement of the nose, while others
  have involvement of multiple organs. Some
  patients primarily have sneezing, itching,
  tearing, and watery rhinorrhea (the classic
  hayfever presentation), while others may only
  complain of congestion. Significant complaints of
  congestion, particularly if unilateral, might
  suggest the possibility of structural
  obstruction, such as a polyp, foreign body, or
  deviated septum.

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Trigger factors

• o        Determine whether symptoms are related
  temporally to specific trigger factors. This
  might include exposure to pollens outdoors, mold
  spores while doing yard work, specific animals,
  or dust while cleaning the house.
• o        Irritant triggers such as smoke,
  pollution, and strong smells can aggravate
  symptoms in a patient with allergic rhinitis.
  These are also common triggers of vasomotor
  rhinitis. Many patients have both allergic
  rhinitis and vasomotor rhinitis.
• o        Other patients may describe year-round
  symptoms that do not appear to be associated with
  specific triggers. This could be consistent with
  nonallergic rhinitis, but perennial allergens,
  such as dust mite or animal exposure, should also
  be considered in this situation. With chronic
  exposure and chronic symptoms, the patient may
  not be able to associate symptoms with a
  particular trigger.

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Response to treatment

• o        Response to treatment with
  antihistamines supports the diagnosis of allergic
  rhinitis, although sneezing, itching, and
  rhinorrhea associated with nonallergic rhinitis
  can also improve with antihistamines.
• o        Response to intranasal corticosteroids
  supports the diagnosis of allergic rhinitis,
  although some cases of nonallergic rhinitis
  (particularly the nonallergic rhinitis with
  eosinophils syndrome NARES) also improve with
  nasal steroids.

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Comorbid conditions

• o        Patients with allergic rhinitis may have
  other atopic conditions such as asthma or atopic
  dermatitis. Of patients with allergic rhinitis,
  20 also have symptoms of asthma. Uncontrolled
  allergic rhinitis may cause worsening of asthma
  or even atopic dermatitis. Explore this
  possibility when obtaining the patient history.
• o        Look for conditions that can occur as
  complications of allergic rhinitis. Sinusitis
  occurs quite frequently. Other possible
  complications include otitis media, sleep
  disturbance or apnea, dental problems (overbite),
  and palatal abnormalities. The treatment plan
  might be different if one of these complications
  is present. Nasal polyps occur in association
  with allergic rhinitis, although whether allergic
  rhinitis actually causes polyps remains unclear.
  Polyps may not respond to medical treatment and
  might predispose a patient to sinusitis or sleep
  disturbance (due to congestion).
• o        Investigate past medical history,
  including other current medical conditions.
  Diseases such as hypothyroidism or sarcoidosis
  can cause nonallergic rhinitis. Concomitant
  medical conditions might influence the choice of
  medication.

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Family history

• o        Because allergic rhinitis has a
  significant genetic component, a positive family
  history for atopy makes the diagnosis more
  likely.
• o        In fact, a greater risk of allergic
  rhinitis exists if both parents are atopic than
  if one parent is atopic. However, the cause of
  allergic rhinitis appears to be multifactorial,
  and a person with no family history of allergic
  rhinitis can develop allergic rhinitis.

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Environmental and occupational exposure

• o        A thorough history of environmental
  exposures helps to identify specific allergic
  triggers. This should include investigation of
  risk factors for exposure to perennial allergens
  (eg, dust mites, mold, pets). Risk factors for
  dust mite exposure include carpeting, heat,
  humidity, and bedding that does not have dust
  miteproof covers. Chronic dampness in the home
  is a risk factor for mold exposure. A history of
  hobbies and recreational activities helps
  determine risk and a time pattern of pollen
  exposure.
• o        Ask about the environment of the
  workplace or school. This might include exposure
  to ordinary perennial allergens (eg, mites, mold,
  pet dander) or unique occupational allergens (eg,
  laboratory animals, animal products, grains and
  organic materials, wood dust, latex, enzymes).

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Effects on quality of life

• o        An accurate assessment of the morbidity
  of allergic rhinitis cannot be obtained without
  asking about the effects on the patient's quality
  of life. Specific validated questionnaires are
  available to help determine effects on quality of
  life.
• o        Determine the presence of symptoms such
  as fatigue, malaise, drowsiness (which may or may
  not be related to medication), and headache.
• o        Investigate sleep quality and ability to
  function at work.

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Physical

• The physical examination should focus on the
  nose, but examination of facial features, eyes,
  ears, oropharynx, neck, lungs, and skin is also
  important. Look for physical findings that may be
  consistent with a systemic disease that is
  associated with rhinitis.

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Physical

•          General facial features
•          Nose
•          Ears, eyes, and oropharynx
•          Neck
•          Lungs
•          Skin
•          Other

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Nose

• The nasal examination is best accomplished with
  a nasal speculum or an otoscope with nasal
  adapter. In the specialist's office, a rigid or
  flexible rhinolaryngoscope may be used.
• The mucosa of the nasal turbinates may be
  swollen (boggy) and have a pale, bluish-gray
  color. Some patients may have predominant
  erythema of the mucosa, which can also be
  observed with rhinitis medicamentosa, infection,
  or vasomotor rhinitis. While pale, boggy,
  blue-gray mucosa is typical for allergic
  rhinitis, mucosal examination findings cannot
  definitively distinguish between allergic and
  nonallergic causes of rhinitis.
• Assess the character and quantity of nasal
  mucus. Thin and watery secretions are frequently
  associated with allergic rhinitis, while thick
  and purulent secretions are usually associated
  with sinusitis however, thicker, purulent,
  colored mucus can also occur with allergic
  rhinitis.
• Examine the nasal septum to look for any
  deviation or septal perforation, which may be
  present due to chronic rhinitis, granulomatous
  disease, cocaine abuse, prior surgery, topical
  decongestant abuse, or, rarely, topical steroid
  overuse.
• Examine the nasal cavity for other masses such
  as polyps or tumors. Polyps are firm gray masses
  that are often attached by a stalk, which may not
  be visible. After spraying a topical
  decongestant, polyps do not shrink, while the
  surrounding nasal mucosa does shrink.

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Ears, eyes, and oropharynx

• o        Perform otoscopy to look for tympanic
  membrane retraction, air-fluid levels, or
  bubbles. Performing pneumatic otoscopy can be
  considered to look for abnormal tympanic membrane
  mobility. These findings can be associated with
  allergic rhinitis, particularly if eustachian
  tube dysfunction or secondary otitis media is
  present.
• o        Ocular examination may reveal findings
  of injection and swelling of the palpebral
  conjunctivae, with excess tear production.
  Dennie-Morgan lines (prominent creases below the
  inferior eyelid) are associated with allergic
  rhinitis.
• o        The term cobblestoning" is used to
  describe streaks of lymphoid tissue on the
  posterior pharynx, which is commonly observed
  with allergic rhinitis. Tonsillar hypertrophy can
  also be observed. Malocclusion (overbite) and a
  high-arched palate can be observed in patients
  who breathe from their mouths excessively.

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•          Neck Look for evidence of
  lymphadenopathy or thyroid disease.
•          Lungs Look for the characteristic
  findings of asthma.
•          Skin Evaluate for possible atopic
  dermatitis.
•          Other Look for any evidence of
  systemic diseases that may cause rhinitis (eg,
  sarcoidosis, hypothyroidism, immunodeficiency,
  ciliary dyskinesia syndrome, other connective
  tissue diseases).

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Causes

• The causes of allergic rhinitis may differ
  depending on whether the symptoms are seasonal,
  perennial, or sporadic/episodic. Some patients
  are sensitive to multiple allergens and can have
  perennial allergic rhinitis with seasonal
  exacerbations. While food allergy can cause
  rhinitis, particularly in children, it is rarely
  a cause of allergic rhinitis in the absence of
  gastrointestinal or skin symptoms.

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Pollens (tree, grass, and weed)

•         Tree pollens, which vary by geographic
  location, are typically present in high counts
  during the spring, although some species produce
  their pollens in the fall. Common tree families
  associated with allergic rhinitis include birch,
  oak, maple, cedar, olive, and elm.
•         Grass pollens also vary by geographic
  location. Most of the common grass species are
  associated with allergic rhinitis, including
  Kentucky bluegrass, orchard, redtop, timothy,
  vernal, meadow fescue, Bermuda, and perennial
  rye. A number of these grasses are
  cross-reactive, meaning that they have similar
  antigenic structures (ie, proteins recognized by
  specific IgE in allergic sensitization).
  Consequently, a person who is allergic to one
  species is also likely to be sensitive to a
  number of other species. The grass pollens are
  most prominent from the late spring through the
  fall but can be present year-round in warmer
  climates.
•         Weed pollens also vary geographically.
  Many of the weeds, such as short ragweed, which
  is a common cause of allergic rhinitis in much of
  the United States, are most prominent in the late
  summer and fall. Other weed pollens are present
  year-round, particularly in warmer climates.
  Common weeds associated with allergic rhinitis
  include short ragweed, western ragweed, pigweed,
  sage, mugwort, yellowdock, sheep sorrel, English
  plantain, lamb's quarters, and Russian thistle.

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Outdoor molds

• Atmospheric conditions can affect the growth and
  dispersion of a number of molds therefore, their
  airborne prevalence may vary depending on climate
  and season.
• For example, Alternaria and Cladosporium are
  particularly prevalent in the dry and windy
  conditions of the Great Plains states, where they
  grow on grasses and grains. Their dispersion
  often peaks on sunny afternoons. They are
  virtually absent when snow is on the ground in
  winter, and they peak in the summer months and
  early fall.
• Aspergillus and Penicillium can be found both
  outdoors and indoors (particularly in humid
  households), with variable growth depending on
  the season or climate. Their spores can also be
  dispersed in dry conditions.
• Perennial allergic rhinitis is typically caused
  by allergens within the home but can also be
  caused by outdoor allergens that are present
  year-round. In warmer climates, grass pollens can
  be present throughout the year. In some climates,
  individuals may be symptomatic due to trees and
  grasses in the warmer months and molds and weeds
  in the winter.

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House dust mites

•   2 major house dust mite species are associated
  with allergic rhinitis. These are
  Dermatophagoides farinae and Dermatophagoides
  pteronyssinus.
• These mites feed on organic material in
  households, particularly the skin that is shed
  from humans and pets. They can be found in
  carpets, upholstered furniture, pillows,
  mattresses, comforters, and stuffed toys.
• While they thrive in warmer temperatures and
  high humidity, they can be found year-round in
  many households. On the other hand, dust mites
  are rare in arid climates.

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Pets

• Allergy to indoor pets is a common cause of
  perennial allergic rhinitis.
• Cat and dog allergies are encountered most
  commonly in allergy practice, although allergy
  has been reported to occur with most of the furry
  animals and birds that are kept as indoor pets.

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• o        Cockroaches While cockroach allergy is
  most frequently considered a cause of asthma,
  particularly in the inner city, it can also cause
  perennial allergic rhinitis in infested
  households.
• o        Rodents Rodent infestation may be
  associated with allergic sensitization.

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Sporadic allergic rhinitis

•         Intermittent brief episodes of allergic
  rhinitis, is caused by intermittent exposure to
  an allergen. Often, this is due to pets or
  animals to which a person is not usually exposed.
  Sporadic allergic rhinitis can also be due to
  pollens, molds, or indoor allergens to which a
  person is not usually exposed. While allergy to
  specific foods can cause rhinitis, an individual
  affected by food allergy also usually has some
  combination of gastrointestinal, skin, and lung
  involvement. In this situation, the history
  findings usually suggest an association with a
  particular food. Watery rhinorrhea occurring
  shortly after eating may be vasomotor (and not
  allergic) in nature, mediated via the vagus nerve
  (This often is called gustatory rhinitis.).

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Occupational allergic rhinitis

•          is caused by exposure to allergens in
  the workplace, can be sporadic, seasonal, or
  perennial. People who work near animals (eg,
  veterinarians, laboratory researchers, farm
  workers) might have episodic symptoms when
  exposed to certain animals, daily symptoms while
  at the workplace, or even continual symptoms
  (which can persist in the evenings and weekends
  with severe sensitivity due to persistent
  late-phase inflammation). Some workers who may
  have seasonal symptoms include farmers,
  agricultural workers (exposure to pollens,
  animals, mold spores, and grains), and other
  outdoor workers. Other significant occupational
  allergens that may cause allergic rhinitis
  include wood dust, latex (due to inhalation of
  powder from gloves), acid anhydrides, glues, and
  psyllium (eg, nursing home workers who administer
  it as medication).

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Problems to be Considered

• Vasomotor rhinitisGustatory rhinitis (vagally
  mediated)Rhinitis medicamentosa (eg, due to
  topical decongestants, antihypertensives, cocaine
  abuse)Hormonal rhinitis (eg, related to
  pregnancy, hypothyroidism, oral contraceptive
  use)Anatomic rhinitis (eg, deviated septum,
  choanal atresia, adenoid hypertrophy, foreign
  body, nasal tumor)NARES Immotile cilia syndrome
  (ciliary dyskinesis)Cerebrospinal fluid
  leakNasal polypsGranulomatous rhinitis (eg,
  Wegener granulomatosis, sarcoidosis)

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Lab Studies

• Allergy skin tests
• In vitro allergy tests, (RAST)
• Testing every patient for sensitivity to every
  allergen known is not practical. Therefore,
  select a limited number of allergens for testing
  (this applies to both skin testing and RAST).
  When selecting allergens, select from among the
  allergens that are present locally and are known
  to cause clinically significant allergic disease.
  A clinician who is specifically trained in
  allergy testing should select allergens for
  testing.
• Total serum IgE
• Total blood eosinophil count

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Imaging Studies

• Radiography
• Sinus films
• Neck films
• CT scanning
• MRI

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•          CT scanning Coronal CT scan images of
  the sinuses can be very helpful for evaluating
  acute or chronic sinusitis. In particular,
  obstruction of the osteomeatal complex (a
  confluence of drainage channels from the sinuses)
  can be seen quite clearly. CT scanning may also
  help delineate polyps, turbinate swelling, septal
  abnormalities (eg, deviation), and bony
  abnormalities (eg, concha bullosa).
•          MRI For evaluating sinusitis, MRI
  images are generally less helpful than CT scan
  images, largely because the bony structures are
  not seen as clearly on MRI images. However, soft
  tissues are visualized quite well, making MRI
  images helpful for diagnosing malignancies of the
  upper airway.

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Nasal cytology

• A nasal smear can sometimes be helpful for
  establishing the diagnosis of allergic rhinitis.
  A sample of secretions and cells is scraped from
  the surface of the nasal mucosa using a special
  sampling probe. Secretions that are blown from
  the nose are not adequate. The presence of
  eosinophils is consistent with allergic rhinitis
  but also can be observed with NARES. Results are
  neither sensitive nor specific for allergic
  rhinitis and should not be used exclusively for
  establishing the diagnosis.

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Procedures

• Rhinoscopy
• Nasal provocation (allergen challenge) testing

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Rhinoscopy

•          While not routinely indicated, upper
  airway endoscopy (rhinolaryngoscopy) can be
  performed if a complication or comorbid condition
  may be present. It can be helpful for evaluating
  structural abnormalities (eg, polyps, adenoid
  hypertrophy, septal deviation, masses, foreign
  bodies) and chronic sinusitis (by visualizing the
  areas of sinus drainage).

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Nasal provocation (allergen challenge) testing

• This procedure is essentially a research tool
  and is rarely indicated in the routine evaluation
  of allergic rhinitis. The possible allergen is
  inhaled or otherwise inoculated into the nose.
  The patient can then be monitored for development
  of symptoms or production of secretions, or
  objective measurements of nasal congestion can be
  taken. Some consider this test the criterion
  standard test for the diagnosis of allergic
  rhinitis. However, it is not a practical test to
  perform routinely, and only an appropriately
  trained specialist should perform this test.

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• The management of allergic rhinitis consists of 3
  major categories of treatment,
• environmental control measures and allergen
  avoidance,
• pharmacological management,
• immunotherapy

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Environmental control measures and allergen
avoidance

•          These involve both the avoidance of
  known allergens (substances to which the patient
  has IgE-mediated hypersensitivity) and avoidance
  of nonspecific, or irritant, triggers. Consider
  environmental control measures, when practical,
  in all cases of allergic rhinitis. However,
  global environmental control without
  identification of specific triggers is
  inappropriate.

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Pollens and outdoor molds

•          Because of their widespread presence in
  the outdoor air, pollens can be difficult to
  avoid. Reduction of outdoor exposure during the
  season in which a particular type of pollen is
  present can be somewhat helpful. In general, tree
  pollens are present in the spring, grass pollens
  from the late spring through summer, and weed
  pollens from late summer through fall, but
  exceptions to these seasonal patterns exist.
•          Pollen counts tend to be higher on dry,
  sunny, windy days. Outdoor exposure can be
  limited during this time, but this may not be
  reliable because pollen counts can also be
  influenced by a number of other factors. Keeping
  the windows and doors of the house and car closed
  as much as possible during the pollen season
  (with air conditioning, if necessary, on
  recirculating mode) can be helpful. Taking a
  shower after outdoor exposure can be helpful by
  removing pollen that is stuck to the hair and
  skin.
•          Despite all of these measures, patients
  who are allergic to pollens usually continue to
  be symptomatic during the pollen season and
  usually require some other form of management. As
  with pollens, avoidance of outdoor/seasonal molds
  may be difficult.

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Indoor allergens

• Depending on the allergen, environmental control
  measures for indoor allergens can be quite
  helpful. For dust mites, covering the mattress
  and pillows with impermeable covers helps reduce
  exposure. Bed linens should be washed every 2
  weeks in hot (at least 130F) water to kill any
  mites present. Thorough and efficient vacuum
  cleaning of carpets and rugs can help, but,
  ultimately, carpeting should be removed. The
  carpet can be treated with one of a number of
  chemical agents that kill the mites or denature
  the protein, but the efficacy of these agents
  does not appear to be dramatic. Dust mites thrive
  when indoor humidity is above 50, so
  dehumidification, air conditioning, or both is
  helpful.
• Indoor environmental control measures for mold
  allergy focus on reduction of excessive humidity
  and removal of standing water. The environmental
  control measures for dust mites can also help
  reduce mold spores.
• For animal allergy, complete avoidance is the
  best option. For patients who cannot, or who do
  not want to, completely avoid an animal or pet,
  confinement of the animal to a noncarpeted room
  and keeping it entirely out of the bedroom can be
  of some benefit. Cat allergen levels in the home
  can be reduced with high-efficiency particulate
  air (HEPA) filters and by bathing the cat every
  week (although this may be impractical).
  Cockroach extermination may be helpful for cases
  of cockroach sensitivity.

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• o        Occupational allergens As with indoor
  allergens, avoidance is the best measure. When
  this is not possible, a mask or respirator might
  be needed.
• o        Nonspecific triggers Exposure to smoke,
  strong perfumes and scents, fumes, rapid changes
  in temperature, and outdoor pollution can be
  nonspecific triggers in patients with allergic
  rhinitis. Consider avoidance of these situations
  or triggers if they seem to aggravate symptoms.

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Immunotherapy (desensitization)

• A considerable body of clinical research has
  established the effectiveness of high-dose
  allergy shots in reducing symptoms and medication
  requirements. Success rates have been
  demonstrated to be as high as 80-90 for certain
  allergens. It is a long-term process noticeable
  improvement is often not observed for 6-12
  months, and, if helpful, therapy should be
  continued for 3-5 years. Immunotherapy is not
  without risk because severe systemic allergic
  reactions can sometimes occur. For these reasons,
  carefully consider the risks and benefits of
  immunotherapy in each patient and weigh the risks
  and benefits of immunotherapy against the risks
  and benefits of the other management options.

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Immunotherapy

• o        Indications Immunotherapy may be
  considered more strongly with severe disease,
  poor response to other management options, and
  the presence of comorbid conditions or
  complications. Immunotherapy is often combined
  with pharmacotherapy and environmental control.
• o        Administration Administer immunotherapy
  with allergens to which the patient is known to
  be sensitive and that are present in the
  patient's environment (and cannot be easily
  avoided). The value of immunotherapy for pollens,
  dust mites, and cats is well established. The
  value of immunotherapy for dogs and mold is less
  well established.
• o        Contraindication A number of potential
  contraindications to immunotherapy exist and need
  to be considered. Immunotherapy should only be
  performed by individuals who have been
  appropriately trained, who institute appropriate
  precautions, and who are equipped for potential
  adverse events.

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Surgical Care

• Surgical care is not indicated for allergic
  rhinitis but may be indicated for comorbid or
  complicating conditions, such as chronic
  sinusitis, severe septal deviation (causing
  severe obstruction), nasal polyps, or other
  anatomical abnormalities. The value of
  turbinectomy is not established.

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Second-generation antihistamines

• Often referred to as the nonsedating
  antihistamines. They compete with histamine for
  histamine receptor type 1 (H1) receptor sites in
  the blood vessels, GI tract, and respiratory
  tract, which in turn inhibits physiologic effects
  that histamine normally induces at the H1
  receptor sites. Some do not appear to produce
  clinically significant sedation at usual doses,
  while others have a low rate of sedation. Other
  adverse effects (eg, anticholinergic symptoms)
  are generally not observed.
• cetirizine, desloratadine, fexofenadine, and
  loratadine

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Leukotriene receptor antagonists

• Alternative to oral antihistamine to treat
  allergic rhinitis. One of the leukotriene
  receptor antagonists, montelukast (Singulair),
  has been approved in the United States for
  treatment of seasonal allergic rhinitis. When
  used as single agent, produces modest improvement
  in allergic rhinitis symptoms.

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First-generation antihistamines

• The older, first-generation H1 antagonists (eg,
  diphenhydramine, hydroxyzine) are effective in
  reducing most symptoms of allergic rhinitis, but
  they produce a number of adverse effects (eg,
  drowsiness, anticholinergic effects). They can be
  used prn, but adverse effects may limit their
  usefulness when taken on a daily basis. Some
  patients tolerate the adverse effects with
  prolonged use, but they may experience cognitive
  impairment, and driving skills may be affected.
  Administration at bedtime may help with
  drowsiness, but sedation and impairment of
  cognition may continue until the next day.

48
Decongestants

• Stimulate vasoconstriction by directly
  activating alpha-adrenergic receptors of the
  respiratory mucosa. Pseudoephedrine produces weak
  bronchial relaxation (unlike epinephrine or
  ephedrine) and is not effective for treating
  asthma. Increases heart rate and contractility by
  stimulating beta-adrenergic receptors. Used alone
  or in combination with antihistamines to treat
  nasal congestion. Anxiety and insomnia may occur.
  Expectorants may thin and loosen secretions,
  although experimental evidence for their efficacy
  is limited. Numerous preparations are available
  containing combinations of various decongestants,
  expectorants, or antihistamines. Alternatively, a
  separate decongestant and antihistamine can be
  administered to allow for individual dose
  titration of each drug.

49
Nasal corticosteroids

• Nasal steroid sprays are highly efficacious in
  treating allergic rhinitis. They control the 4
  major symptoms of rhinitis (ie, sneezing,
  itching, rhinorrhea, congestion). They are
  effective as monotherapy, although they do not
  significantly affect ocular symptoms. Studies
  have shown nasal steroids to be more effective
  than monotherapy with nasal cromolyn or
  antihistamines. Greater benefit may occur when
  nasal steroids are used with other classes of
  medication. They are safe to use and not
  associated with significant systemic adverse
  effects in adults (this may also be true for
  children, but the data are less clear).

50
Nasal corticosteroids

• Local adverse effects are limited to minor
  irritation or nasal bleeding, which resolve with
  temporary discontinuation of the medication.
  Nasal septal perforations are rarely reported and
  are less common with the newer corticosteroids
  and delivery systems. Safety during pregnancy has
  not been established however, clinical
  experience suggests nasal corticosteroids
  (particularly beclomethasone, which has most
  experience in use) are not associated with
  adverse fetal effects.
• The nasal steroids can be used prn, but seem to
  be maximally effective when used on a daily basis
  as maintenance therapy. They may also be helpful
  for vasomotor rhinitis or mixed rhinitis (a
  combination of vasomotor and allergic rhinitis)
  and can help to control nasal polyps.

51
Intranasal cromolyns

• Produce mast cell stabilization and antiallergic
  effects that inhibit degranulation of mast cells.
  Have no direct anti-inflammatory or
  antihistaminic effects. Effective for
  prophylaxis. May be used just before exposure to
  a known allergen (eg, animal, occupational).
  Begin treatment 1-2 wk before pollen season and
  continue daily to prevent seasonal allergic
  rhinitis. Effect is modest compared with that of
  intranasal corticosteroids. Excellent safety
  profile and are thought to be safe for use in
  children and pregnancy.

52
Intranasal anticholinergic agents

• Used for reducing rhinorrhea in patients with
  allergic or vasomotor rhinitis. No significant
  effect on other symptoms. Can be used alone or in
  conjunction with other medications. In the United
  States, ipratropium bromide (Atrovent Nasal
  Spray) is available in a concentration of 0.03
  (officially indicated for treatment of allergic
  and nonallergic rhinitis) and 0.06 (officially
  indicated for the treatment of rhinorrhea
  associated with common cold). The 0.03 strength
  is discussed.

53
Medical/Legal Pitfalls

• o        While patients with allergic rhinitis
  may experience sedation and fatigue secondary to
  the disease process itself, sedation may occur
  due to medications. Most commonly, sedation is
  related to antihistamines, particularly the
  first-generation agents. In many states, driving
  while taking a first-generation, or sedating,
  antihistamine is illegal. Caution any patient who
  is taking a medication that has potential
  sedative effects about driving and operating
  heavy machinery.
• o        A potential area of medicolegal concern
  is the failure to diagnose a comorbid condition
  or complication. Allergic rhinitis can occur in
  conjunction with other atopic diseases, such as
  asthma. Because asthma can be severe and even
  fatal, failure to diagnose concomitant asthma can
  lead to serious adverse events. Failure to
  diagnose potentially serious medical conditions
  that should be considered in the differential
  diagnosis of allergic rhinitis (eg, intranasal
  malignancy) might lead to serious consequences.
  Also, complications of allergic rhinitis (eg,
  sinusitis) can be serious and must be recognized
  when present.