Do Antibiotics Affect The Morning After Pill?

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If you’re wondering whether it’s okay to take the morning after pill while you’re on antibiotics, you’ve come to the right place.

Lou Brack*, Head of Nursing at Brook Sexual Health charity, filled us in on which medicines can interact with emergency contraception.

First things first: hormonal emergency contraception, also known as the morning after pill, works by delaying ovulation after unprotected sex or contraceptive failure.

As sperm can survive in the womb for up-to five days, you could fall pregnant after unprotected sex even if you ovulate a few days after sex.

The morning after pill can help prevent ovulation, so no egg is released and therefore it cannot merge with the sperm and you cannot get pregnant.

If an egg has already been fertilised before taking the morning after pill, emergency contraception does not cause an abortion.

There are two types of active morning after pill ingredients available in the UK: ulipristal acetate, which is found in emergency contraceptive pill ellaOne, and levonorgestrel.

Ulipristal acetate is the most effective morning after pill ingredient and is 2.5 times more effective than levonorgestrel.**

The good news is that most antibiotics can be taken with both ellaOne or levonorgestrel without making it any less effective.

“Levonorgestrel and ulipristal acetate are both generally safe to take in conjunction with antibiotics and the antibiotics will not affect the efficacy of the morning after pill,” Lou says.

There are, however, a few exceptions. Liver enzyme-inducing medication can make ellaOne and levonorgestrel less effective.

There are two types of antibiotics which fall under this category: rifampicin and rifabutin. These antibiotics are fairly rare and are often used to treat tuberculosis and meningitis.

Both rifampicin and rifabutin can make ellaOne less effective for up to 28 days after you finish the dose.

Before purchasing emergency contraception, have a chat with your doctor or pharmacist about any medications you are taking so they can help you to make an informed choice.

The morning after pill is not recommended if you are allergic to any of the ingredients. See here for a full list of ingredients, which can also be found on ellaOne packaging.

Ulipristal acetate is also not recommended if you have severe asthma and use oral steroids to control it. “This is because of the anti glucocorticoid effect of the ulipristal acetate,” says Lou Brack.

“Some enzyme-inducing medicines can reduce plasma levels of levonorgestrel and ulipristal acetate, which make it less effective,” Lou continues, “if you have used enzyme-inducing drugs in the past 4 weeks and need emergency contraception, you should consider using non-hormonal emergency contraception.”

Enzyme-inducing medication can be found in some anti-epilepsy medications and antiretroviral drugs. Consult your doctor or pharmacist if you have any concerns.

St John’s wort, the anti-fungal medication griseofulvin, and the central nervous system stimulant modafinil also fall into this category and may reduce the effectiveness of ellaOne.

HIV medication and barbiturates, which are used to prevent seizures, may also impact the effectiveness of emergency contraception.

Talk to your doctor or pharmacist about any medications you are taking, or any other concerns you might have, so you can make an informed choice. Remember that healthcare professionals are there to help you make the best decision, they are not there to judge or to intimidate.

Have you ever taken the morning after pill? Share your story using the button below and join the #MyMorningAfter community to show people that they are not alone and using emergency contraception is nothing to be ashamed of.

ellaOne® 30mg film-coated tablet contains ulipristal acetate and is indicated for emergency contraception within 120 hours (5 days) of unprotected sex or contraceptive failure. Always read the label.