If used and maintained correctly, eye drops should remain safe and effective until the expiration date, unless otherwise specified in the package insert. When the bottle's sterile seal is broken, there's a risk of contamination, especially if the bottle's tip comes into contact with your eye or any other surface. Preservatives are used in most eye drops to inhibit the growth of bacteria, viruses, and fungi. They help keep the medication safe until it expires. However, some eye drops need to be discarded a couple of days after opening. Others eye drops may contain preservatives but will expire sooner, after they are opened. It's important to preserve your eye drops according to the instructions on the bottle or package insert. Some drops should be kept at room temperature, while others should be refrigerated. These directions may change once the bottle is opened. If the drops aren't stored properly even for a short time, they may lose their effectiveness. If you're not sure how the medication has been stored, it's best to discard it and buy a new bottle. If you're not sure how long you can use your drops, check with your doctor or a pharmacist.