Does Plan B expire? Yes, and it may be less effective if you take it

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This article was medically reviewed by Lauren Demosthenes, MD, OB-GYN, senior medical director at Babyscripts.

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• Plan B has an expiration date of about four years.
• Taking expired Plan B is not dangerous, but it may be less effective in preventing pregnancy.
• To prolong the life of Plan B, keep the pill away from humid, hot, or bright environments.

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Plan B is a form of emergency contraception that prevents unwanted pregnancies after having unprotected sex. Plan B is most effective when taken within 72 hours and works to prevent pregnancy by delaying ovulation.

Because plan B is most effective when taken as soon as possible after engaging in unprotected sex, some people like to keep it on hand. However, it's important to keep in mind that Plan B does expire.

Yes, Plan B does expire

Plan B expires after about four years, says Melissa Sörgel, a licensed pharmacist at OTC Beratung in Germany. Once the expiration date passes, the company that manufactures Plan B is no longer liable for any side effects or other issues.

"However, the drug is not completely ineffective after the expiration date," says Sörgel. "Although, it may no longer be fully effective. It is advisable to not use an expired pill in order to avoid the risk of a pregnancy."

Important: The expiration date is printed on the left side of each container of Plan B.

The expiration date does not change even if you've opened the pill, but decide not to use it, says Sörgel. However, you should keep plan B in the original box even after opening to protect the pill from the light, which could damage it, she says.

Other birth controls, such as Ella, have a slightly shorter shelf life at three years, says Sörgel.

How to store your Plan B safely

If you buy Plan B for potential use at a later date, it's important that you safely store the pill to avoid it breaking up.

According to Peace Nwegbo-Banks, MD, an OBGYN at Serenity Women's Health & Med Spa, you should store Plan B at room temperature, between 68 and 77 degrees Fahrenheit.

Excessive heat can also be detrimental to Plan B's functionality. "Any heat that gets trapped in the package would increase the rate of pills breaking down and probably crumble into a powder — thus lowering the effective dose of the hormone in the pills," says Paula Anderson, MD, an OBGYN.

To store plan B safely and ensure its effectiveness, you should:

• Be careful of light and heat. Keep Plan B in a medicine cabinet or drawer that doesn't receive direct sunlight and has at least some airflow, as these can limit the effectiveness of the pill.
• Consider humidity. It's best not to store plan B in a bathroom where humidity levels are typically higher. "Plan B should not be exposed to high humidity, because the drug contains hormones and is therefore sensitive to moisture," says Sörgel.

Important: Signs that Plan B should not be used include discoloration or cracks in the tablet, says Sörgel.

Insider's takeaway

When taken within the first three days, Plan B's effectiveness ranges from 75 percent to 89 percent. It expires in about four years and, while the medication doesn't lose all effectiveness immediately, experts advise against using it past the expiration date.

Each package will confirm the exact expiration date on its left side. Once purchased, Plan B must be stored at room temperature and away from sunlight and humidity to preserve its effectiveness.

Related articles from Health Reference:

• Plan B won't affect your fertility, but it can cause other side effects
• Plan B may make your period late, but not for more than one menstrual cycle
• Plan B side effects: what they are and how long they last
• The best foods to eat when you have period cramps — and which foods you should avoid
• Why is my period blood brown? How to know if it's normal and when to see a doctor

Sarah Fielding is a freelance writer covering a range of topics with a focus on mental health and women's issues. She is also the co-founder of Empire Coven, a space for highlighting trailblazing women across New York.