Birth control pills are a form of hormonal contraception that uses synthetic versions of estrogen and progestin to prevent pregnancy. Like all medications, these pills have a finite shelf life and are required to carry an expiration date printed on the packaging. This date is important because, after it passes, the manufacturer can no longer guarantee the medication will be fully effective. Taking expired pills significantly increases the risk of unintended pregnancy due to a loss of potency.
Why Expiration Dates Matter for Effectiveness
The expiration date marked on a blister pack is determined by rigorous testing mandated by regulatory bodies like the U.S. Food and Drug Administration (FDA). This testing assesses the chemical stability of the active ingredients, which are the synthetic hormones. Over time, these compounds naturally break down, a process known as degradation.
The date indicates the point at which the drug is guaranteed to retain its full strength and purity when stored correctly. For most medications, including hormonal contraceptives, this means the pill must contain at least 90% of the active ingredient listed on the label. Once the expiration date passes, the concentration of the hormones, such as ethinyl estradiol and levonorgestrel, begins to drop below this required threshold.
A reduction in hormone concentration means the medication may no longer be strong enough to reliably prevent pregnancy. The primary function of the pill is to suppress the release of an egg (ovulation) and thicken cervical mucus. When the active ingredients degrade, they may fail to suppress the hormones necessary to block ovulation, compromising the pill’s protective effect.
Proper Storage to Maintain Potency
While the expiration date is set by the manufacturer, improper storage can cause the medication to lose effectiveness prematurely. The active hormones in birth control pills are sensitive to environmental factors, which accelerate the degradation process. Improper storage invalidates the manufacturer’s guarantee of stability, even if the expiration date has not yet been reached.
Excessive heat is the most common cause of potency loss in hormonal medications. Storing pill packs in locations that get very hot, such as a car’s glove compartment or near a sunny windowsill, speeds up the chemical breakdown of the active ingredients. High humidity is also detrimental to the stability of the tablets.
For this reason, the bathroom medicine cabinet, which is frequently exposed to steam from showers, is not an ideal storage location. Pills should be kept in a dry environment at consistent room temperature, generally considered to be below 77°F (25°C). Keeping the pill pack in its original packaging in a cool, dark, and dry place, like a bedroom drawer or nightstand, ensures the medication remains fully potent until the printed expiration date.
Safe Disposal and Immediate Action Steps
If a pack of birth control pills has expired or is unused, it should be disposed of safely to prevent accidental ingestion by others or environmental contamination. The most recommended method for disposal is to utilize a community drug take-back program. Many pharmacies and local law enforcement agencies offer secure drop-off boxes for expired medications.
If a take-back program is not immediately accessible, the FDA suggests safe at-home disposal methods. This involves mixing the pills with an unappealing substance, such as used coffee grounds or cat litter. The mixture should then be placed into a sealed container, like a plastic bag, before being thrown into the household trash. This process makes the medication undesirable to children, pets, or individuals who might search the garbage.
If a dose of birth control is accidentally taken past its expiration date, the immediate risk is a potential loss of pregnancy protection. The user should begin using a backup method of contraception, such as condoms, right away and continue using it until a new, unexpired pack of pills is started. It is important to contact a healthcare provider or pharmacist promptly to discuss the situation. A medical professional may recommend taking emergency contraception as a precautionary measure, depending on the circumstances.