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Allergic Conjunctivitis

Mizuho Morrison, DO, Matthieu DeClerck, MD, and Andy Barnett, MD

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Allergic conjunctivitis is a common cause of eye discomfort and erythema. While these patients may have impressive symptoms they can almost always be effectively managed in urgent care.


  • Itchiness is the hallmark of allergic conjunctivitis. 

  • Allergic conjunctivitis is typically bilateral if part of a constellation of seasonal/environmental allergies, but can be unilateral if related to a specific exposure (e.g. pet dander). 

  • Chemosis and cobblestoning of the bulbar conjunctivae are strongly suggestive of allergic etiology. 

  • Nasal glucocorticoids and topical antihistamine eye drops are the mainstays of therapy. 

  • Steroid eye drops should not be used because of the possibility of many significant adverse reactions.

  • Encourage patients to stop rubbing their eyes and use lubricating drops instead.


  • The primary distinguishing feature of allergic conjunctivitis is itching.  

    • Allergic conjunctivitis, like all allergic phenomena, is histamine mediated.

    • Histamine causes itching as well as vasodilation, swelling, etc. 

  • Patients may also complain of discomfort and/or a gritty foreign body sensation.

  • Allergic conjunctivitis is most often bilateral when related to seasonal allergies, but can be unilateral if the affected eye was topically exposed to the allergen when the eye was rubbed. 

    • Unilateral allergic conjunctivitis is often related to touching the eye after exposure to pet dander. 

    • Preservative agents in eye drops and contact lens solutions can be a common cause of bilateral contact allergic conjunctivitis. 

  • Physical exam:

    • Visual acuity should be near normal for isolated allergic conjunctivitis. 

      • Visual acuity should be corrected to normal with the use of a pinhole test if the impairment is related to a superficial etiology. 

    • Discharge is generally clear or can be straw-colored and crusty after waking.

    • A fluorescein exam is recommended to exclude abrasion/foreign body if symptoms are unilateral.  

    • The conjunctival injection is generally diffuse  – similar to infectious etiologies.

    • Cobblestoning of the bulbar conjunctiva with lid eversion is pathognomonic for allergic conjunctivitis.  

    • Swelling of the eyelids is a common feature of allergic conjunctivitis. 

      • “Allergic shiners” can also be seen from burst capillaries related to frequent eye rubbing.

    • Chemosis is a common and often frightening exam finding for patients, which, though dramatic in appearance, is not dangerous. 

  • Treatment Basics:

    • Encourage patients to stop touching/rubbing their eyes. 

      • If they need to touch their eyes, washing their hands beforehand is important.

    • Contact lens wearers should stop wearing contacts while suffering symptoms of allergic conjunctivitis. 

    • Using refrigerated, non-medicated, lubricating drops hourly can significantly reduce symptoms. 

  • Pharmacotherapy:

    • Nasal glucocorticoids (e.g. Flonase) can be helpful especially if there are accompanying symptoms of allergic rhinitis. 

    • Topical antihistamines are preferred over systemic/oral options.

      • Ketotifen (OTC)

      • Olopatadine (OTC) is an excellent option because of day dosing.

      • Azelastine is available by prescription, for patients requesting an Rx. 

    • Naphazoline-Pheniramine (Naphcon-A - OTC) is a combination of antihistamine & vasoconstrictor which can reduce discomfort from chemosis.

      • Vasoconstrictors are best for immediate relief of abrupt symptoms.

      • Vasoconstrictors are not recommended for more than rare dosing for severe symptoms (e.g. no more than for one week). 

    • Topical glucocorticoid eye drops are not recommended as they can increase intraocular pressure and cause corneal clouding.

    • Cromolyn is an option and is safe in pregnancy, but relief takes days-weeks.

  • Topical antihistamines are safe in children 3 years and older although oral antihistamines (e.g. Cetirizine, Diphenhydramine) may be easier to administer for practical reasons. 



  1. Rathi V, et al. Allergic conjunctivitis. Community Eye Health. 2017;30(99):S7-S10.PMID: 29849438

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