Antihistamine eye drops: uses and side effects

You may have no other symptoms alongside your itchy or streaming eyes, in which case eye drops are a good place to start. If you have more generalized symptoms, then antihistamine tablets can be a useful addition, too. They aim to reduce the overall immune response, which is driven by the release of histamine from mast cells.

Antihistamine eye drops such as olopatadine (Pataday) and ketotifen (Alaway, Zaditor) are available without a prescription. Pataday comes in both a once-a-day and twice-a-day formulation and can be used in children 2 years of age and older. Alaway and Zaditor are dosed twice daily and can be used in children 3 years of age and older.

While they are generally well-tolerated, some people may experience mild side effects. Common side effects (less than 1 in 10) can include:

• temporary stinging

• burning sensations

• blurred vision

• redness in the eyes

Uncommon side effects (1 in 100) include:

• headache

• watery eyes

Rare side effects (1 in 1000) include:

• allergic reactions, such as itching, rash, or swelling

It's important to note that serious side effects are rare, but if you experience severe eye pain, persistent irritation, or any other unusual symptoms, it's advisable to seek medical attention promptly.

Stronger antihistamine eye drops are available by prescription.

Cromolyn sodium 4%, such as Opticrom eye drops, is available by prescription for those aged 4 years and above. This active ingredient is not classed as an antihistamine but works to reduce the release of histamine in the eyes and suppress allergy symptoms there. It’s applied four times a day, and can be used as a standalone treatment or alongside oral antihistamines.