Management principles:
- avoidance of allergen if known (1,3)
- topical antihistamines may be useful(2) and oral antihistamines may sometimes have a role (3):
- eye drops of antihistamines such antazoline (with xylometazoline as Otrivine-Antistin®), azelastine, epinastine, ketotifen and olopatadine may be used for allergic conjunctivitis
- not a therapeutic option that is appropriate for prolonged use (no longer than six weeks)
- not an appropriate treatment option in contact dermatoconjunctivitis
- oral antihistamines such as loratadine or chlorphenamine may be used (3):
- especially useful when there is associated allergic rhinitis
- can cause drowsiness, especially the older compounds such as chlorphenamine - patients need to be cautioned regarding this
- the newer-generation oral antihistamines are preferred because they are less sedating
- other possible preparations include: (2)
- sodium cromoglicate (sodium cromoglycate) and nedocromil sodium eye drops - these preparations can be useful for vernal keratoconjunctivitis and other allergic forms of conjunctivitis
- lodoxamide eye drops - this preparation may be used for allergic conjunctival conditions including seasonal allergic conjunctivitis
- diclofenac eye drops and emedastine eye drops are also licensed for seasonal allergic conjunctivitis
- in general, corticosteroid containing ointments or drops should be avoided unless the prescriber is able to monitor accurately for adverse effects e.g. glaucoma, cataract - only used where there is no doubt about the diagnosis. Topical corticosteroids should never be initiated in primary care, and never be given for an undiagnosed red eye, if visual acuity is impaired, or if there is a previous history of ocular herpes simplex.
Reference:
1. American Academy of Ophthalmology. Conjunctivitis preferred practice pattern. Nov 2018 [internet publication]
2. Castillo M, Scott NW, Mustafa MZ, et al. Topical antihistamines and mast cell stabilisers for treating seasonal and perennial allergic conjunctivitis. Cochrane Database Syst Rev. 2015 Jun 1;(6)
3. Azari AA, Barney NP; Conjunctivitis: a systematic review of diagnosis and treatment. JAMA. 2013 Oct 23;310(16):1721-9.