K-FEN 0.5 Eye Drop is used to treat inflammation (redness and swelling) due to allergies of the eye. It helps provides relief from red, itchy, and watery eyes. K-FEN 0.5 Eye Drop is for external use only. Follow the instructions given by your doctor and use this medicine regularly to get the most benefit. You should gently squeeze the dropper and place the medicine inside the lower eyelid and wipe off extra liquid. Always wash your hands and do not touch the end of the dropper. This could infect your eye. Make sure you remove contact lenses if you wear them and wait for at least 15 minutes before putting them back. Never use a bottle if the seal is broken before you use it for the first time. The most common side effects of this medicine include eye irritation, eye pain, and punctate keratitis. These are usually temporary and resolve with time. Do not drive, use machinery, or do any activity that requires clear vision until you are sure you can do it safely. Consult your doctor if your condition does not improve or if the side effects bother you. Do not use this medicine, if you have an eye problem (glaucoma) and untreated eye infection. Your doctor should also know about all other medicines you are taking as many of these may make this medicine less effective or change the way it works.