What are common antihistamine eye drops for allergic conjunctivitis?

Common Antihistamine Eye Drops for Allergic Conjunctivitis

Dual-action topical antihistamine/mast cell stabilizers are the most effective first-line therapy for allergic conjunctivitis, providing both immediate symptom relief and prevention of symptoms. 1

First-Line Options

The most commonly used antihistamine eye drops include:

1. Dual-action agents (antihistamine + mast cell stabilizer):

   • Olopatadine - twice daily for ages >3 years 1
   • Ketotifen - twice daily for ages >3 years 1, 2
   • Epinastine - twice daily for ages >12 years 1
   • Azelastine - 2-4 times daily for ages >4 years 1

2. Pure antihistamines:

   • Emedastine (Emadine)
   • Levocabastine (Livostin) 3

Clinical Decision Making

When selecting an antihistamine eye drop, consider:

• Ketotifen is now available OTC at original prescription strength for patients 3 years and older, providing up to 12 hours of itch relief 2
• Olopatadine has demonstrated superior efficacy in reducing conjunctival eosinophil infiltration compared to other antihistamines 4
• Newer options like bilastine 0.6% preservative-free eye drops show promise as a once-daily treatment 5

Treatment Algorithm

1. For mild to moderate symptoms:

   • Start with dual-action antihistamine/mast cell stabilizers
   • Ketotifen is a good first choice due to OTC availability and twice-daily dosing 2

2. For severe or unresponsive symptoms:

   • Consider short-term topical corticosteroids (e.g., loteprednol etabonate 0.2%)
   • Use only under ophthalmologist supervision due to risk of intraocular pressure elevation 1

3. For refractory cases:

   • Consider topical cyclosporine or tacrolimus for long-term management 1

Adjunctive Measures

• Cold compresses to reduce local pain and swelling
• Preservative-free artificial tears (2-4 times daily) to dilute allergens and inflammatory mediators
• Avoid direct air drafts and take regular breaks from screen time 1

Important Cautions

• Avoid prolonged use of ocular decongestants/vasoconstrictors (like naphazoline, tetrahydrozoline) as they can cause rebound hyperemia ("conjunctivitis medicamentosa") 3, 1
• Avoid oral antihistamines when possible as they may induce or worsen dry eye syndrome 1
• Avoid punctal plugs as they prevent flushing of allergens from the ocular surface 1

Special Considerations

• For children under 3 years, consult a doctor before using any eye drops 2
• Refer children with allergic conjunctivitis to an ophthalmologist in cases of visual loss, moderate/severe pain, corneal involvement, or lack of response to therapy 1

Clinical studies have demonstrated that ketotifen is significantly more effective than placebo in reducing signs and symptoms of seasonal allergic conjunctivitis 6, making it a reliable choice for many patients.