Expired medications can be less effective or even risky due to a change in chemical composition or a decrease in strength. Also, certain expired medications are at risk of bacterial growth. The U.S. Food and Drug Administration (FDA) is very clear: If a medicine is expired, you shouldn’t use it.
Expired medicines sitting in a home medicine cabinet are highly susceptible to being stolen and misused. Studies show that many abused prescription drugs are obtained from family and friends. Having expired medicines around is not just a risk to the person for whom they were prescribed. If taken by mistake, children and pets can be injured.
Properly disposing of unneeded and expired medicines is important. Follow any specific disposal instructions that may be listed on the label. Do not flush them down the toilet. Ask your pharmacist. If available in your area, a drug take-back program is the preferred way to dispose of expired, unwanted or unused medicine.
Source: The U.S. Food and Drug Administration