What are the indications for antihistamine (Anti-Histamine) eye drops in allergic conjunctivitis?

From the Guidelines

Antihistamine eye drops are a highly effective treatment for eye allergies, and I strongly recommend using them as a first-line treatment for mild to moderate allergic eye symptoms. For mild to moderate allergic eye symptoms, I recommend over-the-counter options like ketotifen (Zaditor, Alaway) or olopatadine (Pataday), used 1-2 drops in each affected eye twice daily 1. These medications work by blocking histamine receptors in the eye, reducing itching, redness, and tearing. Most antihistamine eye drops begin working within minutes and can provide relief for up to 12 hours.

When using these drops, it is essential to wait at least 10 minutes before inserting contact lenses, and avoid touching the dropper tip to prevent contamination. If symptoms persist beyond 72 hours or worsen, it is crucial to consult an eye care professional. These medications are generally safe but may cause mild stinging or burning upon application. For best results, use consistently during allergy season and consider combining with oral antihistamines for severe allergies.

Some key points to consider when using antihistamine eye drops include:

• Always follow the recommended dosage and administration instructions
• Avoid using vasoconstrictor agents for more than 10 days to prevent rebound hyperemia or conjunctivitis medicamentosa
• Consider using mast cell stabilizers for chronic or recurrent ocular allergies
• Topical NSAIDs, such as ketorolac, can be used for temporary relief of ocular itching caused by seasonal allergic conjunctivitis
• Ocular corticosteroids should be reserved for more severe symptoms of allergic conjunctivitis due to the risk of vision-threatening side effects.

It is also important to note that oral antihistamines are generally less effective in relieving ocular allergy symptoms than topical ophthalmic agents and have slower onset of action 1. Therefore, topical antihistamine eye drops are the preferred treatment option for eye allergies.

From the FDA Drug Label

Azelastine hydrochloride ophthalmic solution is indicated for the treatment of itching of the eye associated with allergic conjunctivitis.

• Azelastine is an antihistamine eye drop.
• It is used to treat itching of the eye associated with allergic conjunctivitis.
• The drug is indicated for this specific use, making it a suitable option for allergy symptoms in the eyes 2.

From the Research

Antihistamine Eye Drops for Allergies

• Antihistamine eye drops, such as ketotifen, are effective in reducing the signs and symptoms of seasonal allergic conjunctivitis (SAC) 3, 4.
• Ketotifen blocks histamine H(1) receptors, stabilises mast cells, and prevents eosinophil accumulation, providing multiple mechanisms for treating SAC 3.
• Topical antihistamines and mast cell stabilisers, alone or in combination, are effective in reducing symptoms and signs of seasonal allergic conjunctivitis when compared with placebo 5.
• Ketotifen 0.025% eye drops were found to be more effective and better tolerated than 0.05% in SAC 4.
• Antihistamine eye drops can provide faster and superior relief than systemic antihistamines, and may also possess a longer duration of action than other classes of topical agents 6.

Efficacy of Antihistamine Eye Drops

• Ketotifen 0.025% eye drops were shown to be highly effective in reducing the total signs and symptoms scores (TSSS) in patients with SAC 4.
• The responder rate, based on the subjects' assessment of global efficacy, was significantly greater in the ketotifen group than in the placebo group 3.
• Antihistamine eye drops can reduce symptoms and signs of seasonal allergic conjunctivitis, including itching, redness, and tearing 5, 6.

Safety and Tolerability of Antihistamine Eye Drops

• Ketotifen eye drops were found to be well tolerated and effective in reducing the signs and symptoms of SAC, with no serious adverse events reported 3, 4.
• The most common adverse event reported was burning following instillation, which was experienced by 16% of patients 7.
• Antihistamine eye drops are generally considered safe and well tolerated, with a low risk of adverse events 5.