Symptoms of eye drop overdose can be similar to the medication’s side effects, but are usually more severe. Most eye drop medications for allergies should be used sparingly and for no longer than a week. Eye drop medications that contain decongestants should not be used for more than three consecutive days. Overuse of decongestants can lead to a rebound effect, with redness and swelling actually increasing instead of decreasing.

Corticosteroids can be used to treat eye allergies, but only with caution and under a physician’s close monitoring. Long-term use can lead to pressure buildup in the eye from glaucoma or the formation of cataracts, a clouding of the eye lens that can impact vision.