What are the recommended eye drop treatments for allergic conjunctivitis, including first‑line antihistamine/mast‑cell‑stabilizer options, dosing schedules, when to add a short course of low‑potency corticosteroid, and considerations for chronic/refractory cases and contraindications such as glaucoma, steroid response, or contact lens wear?

Allergy Eye Drop Recommendations

First-Line Treatment: Dual-Action Agents

Start with dual-action topical antihistamine/mast cell stabilizers (olopatadine, ketotifen, epinastine, or azelastine) as first-line therapy for allergic conjunctivitis, as these provide both immediate symptom relief within 30 minutes and ongoing protection against future allergic episodes. 1, 2

Specific Dosing Schedules

• Olopatadine 0.1%: 1 drop in affected eye(s) twice daily, every 6-8 hours, approved for ages ≥2 years 3
• Ketotifen: 1 drop in affected eye(s) twice daily, every 8-12 hours, approved for ages ≥3 years 4
• Azelastine: 1 drop in affected eye(s) twice daily, approved for adults and children 5
• Epinastine: Twice daily dosing, superior to placebo and equal or more effective than olopatadine 0.1% for ocular itch 6

Duration of Use

Unlike corticosteroids, dual-action agents have no specified maximum treatment duration and can be used continuously as long as allergen exposure persists, making them suitable for both acute and chronic/perennial allergic conjunctivitis. 2, 7

Essential Adjunctive Non-Pharmacologic Measures

Implement these simultaneously with topical therapy to maximize symptom control:

• Refrigerated preservative-free artificial tears 4 times daily to dilute allergens and inflammatory mediators on the ocular surface 1, 7
• Cold compresses for immediate symptomatic relief 1, 2
• Store eye drops in the refrigerator for additional cooling relief upon instillation 1
• Wear sunglasses as a physical barrier against airborne allergens 1
• Implement allergen avoidance: hypoallergenic bedding, eyelid cleansers, frequent clothes washing, showering before bedtime 1
• Counsel patients to avoid eye rubbing, which can worsen symptoms and potentially lead to keratoconus, especially in atopic patients 1

When to Add Short-Course Corticosteroids

If symptoms do not improve within 48 hours on dual-action agents, add a brief 1-2 week course of loteprednol etabonate (low side-effect profile topical corticosteroid) for inadequately controlled symptoms or acute exacerbations. 1, 2

Mandatory Monitoring for Corticosteroid Use

• Baseline intraocular pressure (IOP) measurement and pupillary dilation to evaluate for glaucoma and cataract 1, 2
• Periodic IOP monitoring throughout treatment and at follow-up visits 1
• Strictly limit corticosteroid use to 1-2 weeks maximum due to risks of elevated IOP, cataract formation, and secondary infections 1, 2
• Never use corticosteroids as monotherapy or for prolonged periods 7

Alternative Corticosteroid: Fluorometholone

Fluorometholone is appropriate as third-line therapy for severe allergic conjunctivitis or acute exacerbations failing dual-action agents, with the same 1-2 week maximum duration and mandatory IOP monitoring requirements 1

Chronic and Refractory Cases

Second-Line Options for Prophylaxis

Mast cell stabilizers alone (cromolyn, lodoxamide, nedocromil, pemirolast) require several days to achieve optimal symptom relief and are more suitable for prophylactic or longer-term treatment than acute symptom relief. 1, 2

• Sodium cromoglycate: 4 times daily, safest option for all ages including infants with no age restriction 1
• Lodoxamide: 4 times daily for children >4 years 1

Severe/Refractory Disease: Topical Immunomodulators

For severe allergic conjunctivitis (vernal or atopic keratoconjunctivitis) unresponsive to dual-action agents, consider topical cyclosporine 0.05% at least 4 times daily or tacrolimus 0.03-0.1%, which allow for reduced corticosteroid use. 1, 2

• Cyclosporine 0.1% is FDA-approved specifically for vernal keratoconjunctivitis in both children and adults 1
• Cyclosporine demonstrates reduction in signs and symptoms after 2 weeks of treatment 1
• Topical corticosteroids are usually necessary to control severe symptoms in vernal/atopic keratoconjunctivitis initially, then transition to immunomodulators 1

For Sight-Threatening Disease

• Supratarsal corticosteroid injection can be considered for severe atopic keratoconjunctivitis not responsive to topical therapy 1
• Systemic immunosuppression (montelukast, interferons, oral cyclosporine or tacrolimus) is rarely warranted but may be considered with specialist consultation 1

Periocular Involvement

For eyelid involvement in patients ≥2 years, use pimecrolimus cream 1% or topical tacrolimus ointment (0.03% for ages 2-15 years; 0.03% or 0.1% for ages ≥16 years). 1

• Warning: Tacrolimus or pimecrolimus may increase susceptibility to herpes simplex keratitis 1

Critical Pitfalls to Avoid

Contraindications and Cautions

• Never use punctal plugs in allergic conjunctivitis because they prevent flushing of allergens and inflammatory mediators from the ocular surface 1, 7
• Avoid chronic vasoconstrictor use (naphazoline, tetrahydrozoline) beyond 10 days, as prolonged use causes rebound hyperemia (conjunctivitis medicamentosa) 1, 7
• Avoid oral antihistamines as primary treatment because they may worsen dry eye syndrome and impair the tear film's protective barrier 1, 2, 7
• Avoid indiscriminate topical antibiotic use, as they provide no benefit for allergic disease, induce toxicity, and contribute to antibiotic resistance 1

Contact Lens Considerations

Patients should remove contact lenses before instilling eye drops and wait at least 5 minutes before reinsertion (when using multiple ophthalmic products, wait at least 5 minutes between each product) 3

Glaucoma and Steroid Response

Patients with pre-existing glaucoma, steroid responders, or those at risk for elevated IOP require especially close monitoring when any corticosteroid is used, with baseline and periodic IOP measurement plus pupillary dilation mandatory. 1, 2

Follow-Up Strategy

• Frequency of follow-up visits should be based on disease severity, etiology, and treatment response, with visits timed during symptomatic periods 1
• Monitor for keratoconus in patients with atopic disease, as adequate allergy control and preventing eye rubbing can decrease ectasia progression 1, 7
• For perennial allergic conjunctivitis, reassess need for dual-action agents at regular follow-up visits based on symptom control 1

When to Refer

Consult an allergist or ophthalmologist for:

• Disease that cannot be adequately controlled with topical medications 1
• Consideration of allergen-specific immunotherapy (subcutaneous or sublingual) for achieving hyposensitization 1
• Severe vernal or atopic keratoconjunctivitis requiring systemic immunosuppression 1