Optihist Eye Drop is a prescription medicine used to treat allergic diseases of the eye. It relieves redness and swelling of the eye and provides temporary relief from burning and discomfort. Optihist Eye Drop is to be used only in the affected eye in the dose and duration as advised by the doctor. Wash your hands before using this medicine. It is advised to check the label for directions before use. Do not skip any doses and finish the full course of treatment even if you feel better. The most common side effects of this medicine include burning, stinging, and irritation at the site of application. If these side effects persist for a longer duration, inform your doctor. In case by accident, this medicine goes into your ears, nose, or mouth, immediately rinse it with water. Inform your doctor if you are allergic to any ingredients of this medicine or taking any other medication. It is advised not to drive or operate heavy machinery after using this medicine as it may cause temporary blurring of vision and may affect your ability to drive.