Modafinil — a drug used for sleep disorders and ADHD — can reduce the effectiveness of certain types of birth control.

Any medication can come with side effects. But modafinil, also known as Provigil, has some that can come with serious consequences.

It can make some forms of birth control less effective, which may lead to unintended pregnancy.

That’s because it’s an enzyme inducer. It boosts enzyme activity, causing birth control to break down in the body quicker than usual.

Not all forms of birth control are affected if you take modafinil.

The Depo-Provera shot and intrauterine device (IUD) tend to be safe to use alongside the medication.

But doctors advise against using the following hormonal contraceptives and modafinil:

This information has largely come from studies testing other enzyme inducers’ effects on contraceptives. But modafinil itself hasn’t been the focus of large-scale studies.

Modafinil isn’t just thought to reduce birth control effectiveness while taking the two together. It can affect contraception for 1 month after you stop taking modafinil.

It’s also important to realize that hormonal emergency contraception may be affected, too. Instead of taking an emergency contraceptive pill, you’ll usually be offered a copper IUD.

While modafinil is commonly used to treat sleep disorders like narcolepsy, it’s also prescribed off-label for attention deficit hyperactivity disorder (ADHD).

But the potential contraceptive side effects remain the same, no matter what you may be taking modafinil for.

Even people using the medication off-license as a “smart drug” have been warned that it could make their birth control less effective.

So, the safe contraceptive list doesn’t change. Stick to the shot or an IUD.

Enzymes can break down hormones.

So when you take an enzyme-inducing drug like modafinil, enzyme activity will increase in your liver.

This means contraceptive hormones may break down quicker, making birth control potentially less effective as it won’t last as long in the body.

Effectively, more enzyme activity may mean lower hormonal contraceptive levels.

If a medication has a reproductive potential warning, it’ll advise medical professionals if they need to recommend a pregnancy test or contraception before, during, or after their patient takes the drug.

They’ll also be notified of any impacts on fertility the medication may have.

Modafinil doesn’t currently come with such a warning as there’s limited evidence of its effects on pregnancy.

It’s also unclear if modafinil has caused the issues that have been found or whether the findings are merely a coincidence.

Can modafinil affect your fertility?

No human studies have looked at whether modafinil can affect fertility. But animal studies have looked into this area and found no fertility issues.

There have been reports of modafinil affecting fetuses in the uterus, though. So you’ll need to talk with a clinician if you are pregnant or looking to become pregnant and taking modafinil.

What happens if you become pregnant while taking modafinil?

Modafinil can mean a higher risk of fetal developmental issues, such as congenital heart conditions and orofacial clefts.

One study found 15% of babies exposed to modafinil in the uterus were born with congenital malformations compared with 3% of babies in the general population.

A separate study published in 2020 found a similar increased risk of congenital malformations after in utero exposure to modafinil during the first trimester.

However, without more research, it’s difficult to say whether modafinil is causing such structural differences.

The Food and Drug Administration (FDA) says, “there are no adequate and well-controlled studies of modafinil” in pregnant people.

But animal studies have found modafinil can affect fetal growth and development. The FDA states that modafinil should only be used during pregnancy “if the potential benefit justifies the potential risk to the fetus.”

If you’re planning to become pregnant, your clinician will usually find a way for you to stop taking modafinil safely.

What about other stimulant medications — do these affect birth control efficacy at all?

Other medications that boost liver enzyme activity could similarly affect hormonal birth control.

The list could include some barbiturates, antifungal medication, and ADHD treatments.

But there isn’t much research to prove this yet, so doctors are still unclear.

Modafinil can reduce the effectiveness of certain contraceptives and may affect fetal development.

If you’re taking modafinil or may soon be prescribed the medication, it’s important to discuss birth control with your healthcare professional and let them know if you want to become pregnant.

They’ll be able to find the safest and most effective birth control for you. Plus, they can talk you through the medication risks while pregnant and find a safer alternative if needed.

Lauren Sharkey is a U.K.-based journalist and author specializing in women’s issues. When she isn’t trying to discover a way to banish migraine, she can be found uncovering the answers to your lurking health questions. She has also written a book profiling young female activists across the globe and is currently building a community of such resisters. Catch her on Twitter.