======Allergic Rhinitis======
=====Background=====
  * Definition: Inflammation of the nasal membranes in response to known or unknown allergen(s); also known as “hay fever” → rhinorrhea, sneezing, nasal congestion/pruritus
  * Pathophysiology: 1st exposure → production of allergen-specific IgE → IgE binds receptors on mast cells & basophils; subsequent exposures → allergen crosslinks IgE on cell surface → cellular activation (i.e., mast cell degranulation)
  * Epidemiology: Prevalence is increasing; highest in children and teens; currently affects >8% of US adults; accounts for >13 million US health care visits annually (cdc.gov/nchs)
  * Risk factors: Include ⊕ FHx of allergic disease (possibly mediated by genetics [multiple loci]), ↑ exposure to pollutants, dust mites, and early exposure to cigarette smoke (JACI 2011;128:816)
  * Complications: Nasal inflammation sx can affect QoL & productivity; additionally, ↑ incidence/severity of URIs (2/2 mucosal inflammation) & bacterial sinusitis (2/2 sinus obstruction) (Otolaryngol Head Neck Surg 2007;137:S1)
  * Comorbidities: 40% of pts w/ AR also have asthma; tx of AR → improved asthma sx & ↓ hospitalizations (JACI 2002;109:57); ocular sx occur in 50–70% of pts w/ AR (see “Eye Complaints”); also strongly assoc w/ AD (“atopic march”)

=====Evaluation=====
  * General approach: Establish sx severity & potential triggers, consider DDx & assess for comorbidities (OSA, asthma, atopy)
  * History: Assess sx, including functional (impaired sleep & work)
    * Meds: Important to r/o rhinitis medicamentosa as cause of sx (see below); include OTC decongestants & nasal sprays, OCPs, ASA, NSAIDs, anti-HTN
    * PMHx/Soc hx: Hx atopy (asthma, AD), OSA, environmental or food allergies, occupational hx, risk factors (above), current pregnancy, cocaine use

^ Allergic Rhinitis Triggers ^^
| Seasonal | Tree pollen (spring), grasses (summer), weeds (fall) |
| Perennial | Animal hair (cat, dog, etc.), dust mites, cockroaches (urban areas), mold |
| Occupational | Agricultural workers, animal lab workers, food services |

  * Exam: HEENT + skin (atopic dermatitis) & lung (asthma) exam
    * Eyes: Bilateral conjunctival hyperemia ± clear d/c (allergic conjunctivitis), infraorbital “shiners” (↑ venous stasis 2/2 nasal congestion)
    * Ears: Serous otitis media (Eustachian tube dysfunction)
    * Nose: Saddle-nose deformity (granulomatosis w/polyangiitis, or GPA) or septal deviation (trauma) or perforation (cocaine), pallor of mucosa, pallor/edema of turbinates; “allergic salute” (rubbing nasal tip upward w/ palm → supratip crease); polyps (chronic sinusitis, ASA Se)
  * Differential diagnosis: Up to 30% of rhinitis nonallergic
    * Infectious: Acute viral rhinosinusitis, chronic rhinosinusitis (consider immunodeficiency)
    * Medication-induced: S/e of ASA/NSAID, ACEI, PDE5, HCTZ, β-blockers; and OCPs (JACI 2006;16:148) rhinitis medicamentosa (“rebound” 2/2 chronic use of topical nasal decongestants, e.g., oxymetazoline; also seen w/ cocaine)
    * Autoimmune: Churg–Strauss, GPA, sarcoid
    * Idiopathic: Vasomotor rhinitis (nonallergic, noninfectious)
    * Structural: Nasal polyps, deviated septum, adenoid hypertrophy
    * Other: Pregnancy, assoc w/ menstrual cycle (2/2 ↑ circulating estrogen/progesterone)
  * WHO classification (JACI 2001;108:S147)
    * Frequency: Intermittent (<4 d/wk or <4 wk) vs. persistent (>4 d/wk or >4 wk)
    * Severity: Mod–severe (≥1 of the following: sleep disturbance, impaired school/work performance, impaired daily activities, troublesome sx) vs. mild (no significant sx)

=====Management=====
  * Allergen avoidance: Identify/avoid triggers when possible
    * Dust mite: Humidity control, dust mite covers for bedding, HEPA vacuuming of carpeting
    * Pollen: Avoid outdoors during AM (when pollen counts highest), use air conditioners when possible, don’t hang clothes out to dry
    * For further allergen avoidance suggestions, see “Asthma”
  * Nasal irrigation: Beneficial for chronic rhinorrhea; may be used alone or as adjuvant; Neti pot superior to saline mist (advise pts to use sterile saline, risk of N. fowleri); may also be done w/ low-pressure irrigation squeeze bottle (AFP 2010;81:1440)
  * Pharmacotherapy: Multiple tx options; intranasal corticosteroids most effective for mod–severe disease; oral antihistamines reasonable for intermittent or milder disease; avoid topical nasal decongestants b/c of risk of rebound congestion & rhinitis medicamentosa
  * Intranasal therapy technique: Direct spray superiorly/laterally (“toward ipsilateral ear”)

^ Pharmacotherapy ^^
| Class | Example Rx & Notes |
| Intranasal corticosteroids (1st line for mod–severe disease) | Fluticasone (50 μg/spray): 2 sprays/nostril QD or 1 spray/nostril BID \\ Can ↓ to 1 spray/nostril QD for maintenance; onset ~12 h, should be used consistently for ↑ efficacy \\ Also effective in mixed rhinitis (e.g., irritant) \\ S/e: Nasal irritation, epistaxis, bitter taste; systemic s/e rare \\ No difference in efficacy w/in class (J Laryngol Otol 2003;117:843) |
| Oral antihistamines | Fexofenadine (OTC): 60 mg BID or 180 mg once daily \\ Cetirizine 10 mg QD \\ 2nd-generation preferred (↓ sedation, ↓ anticholinergic effects, although may be ↓ effective rhinorrhea tx) \\ Faster onset, less effective than ICS for severe disease or nasal congestion; can be used PRN but more effective if used regularly \\ Fexofenadine/loratadine/desloratadine less sedating, cetirizine more sedating \\ Cetirizine and loratadine are category B for pregnancy |
| Nasal antihistamines | Azelastine 1–2 sprays/nostril BID or olopatadine 2 sprays/nostril BID \\ Equal or superior efficacy to oral Rx for nasal sx; less effective than intranasal corticosteroids \\ S/e: Bitter taste, somnolence \\ May be given in combination with glucocorticoid sprays and oral antihistamines |
| Intranasal anticholinergics | Ipratropium (0.03%): 2 sprays/nostril BID–TID \\ Good for ↓ rhinorrhea; not effective at ↓ congestion |
| Leukotriene receptor antagonists | Montelukast 10 mg PO QD; also effective in asthma (consider use in pts w/ both diseases); similar efficacy in AR to oral antihistamines |

  * Other:
    * Mast cell stabilizer (intranasal cromolyn): Can be used as ppx (take just before exposure → 4–8 h protection) or maintenance (best if started prior to exposure); less effective than intranasal corticosteroids
    * Acupuncture: Nonpharmacologic therapy; may ↑ QoL and ↓ symptoms (Ann Allergy Asthma Immunol 2015:115:4)
    * Oral decongestants: Pseudoephedrine: IR: 60 mg q4–6h; Extended release: 120 mg q12h or 240 mg QD (max 240 mg/24 h); unclear efficacy—may be no better than placebo; use only short term (5–7 d) (JACI In Practice 2015;3:5); S/e: HTN, insomnia, palpitations, urinary retention
  * When to Refer
    * Allergy/immunology: For severe/refractory/recurrent sx; for allergen-specific IgE skin/serum testing; if dx uncertain; for treatment with sublingual immunotherapy (ragweed or grass pollen) or subQ immunotherapy (desensitization, “allergy shots,” often requires 3–5 y of tx) to alter immune response
    * Otolaryngology: If suspect structural etiology (e.g., deviated septum, nasal obstruction)