Opatanol is used to treat the eye symptoms of seasonal allergic conjunctivitis (inflammation of the eyes caused by pollen in patients with hayfever). These include itching, redness and swelling.
The most common side effects with Opatanol (seen in between 1 and 10 patients in 100) are headache, dysgeusia (taste disturbances), eye pain, eye irritation, dry eyes, abnormal sensations in the eye, dry nose and fatigue (tiredness).
You should remove contact lenses before using this medicine and put them back 15 minutes afterwards. Benzalkonium chloride may also cause eye irritation, especially if you have dry eyes or disorders of the cornea (the clear layer at the front of the eye).