Modafinil and pregnancy: birth defect risk, contraception and breastfeeding

Modafinil and pregnancy do not mix: UK guidance says modafinil should not be used during pregnancy because it may raise the chance of birth defects. It can also make hormonal contraception, including the pill, less effective. If you could get pregnant, you need effective contraception while taking it and for two months after stopping.

This guide explains what the UK medicines regulator says about modafinil, pregnancy and contraception. It covers the evidence, which contraceptive methods still work, and what to do if you are planning a baby or find out you are pregnant. For an overview of the medicine, read our complete guide to modafinil.

Why modafinil is not used in pregnancy

In November 2020 the MHRA issued a Drug Safety Update on modafinil in pregnancy. It said modafinil potentially increases the risk of congenital malformations, which are problems with how a baby’s body forms before birth.

The malformations reported included heart defects, hypospadias (where the opening of the penis is not at the tip) and cleft lip or palate. The MHRA’s advice is that modafinil should not be used in pregnancy. It asks doctors to consider other narcolepsy treatments instead.

The UK Summary of Product Characteristics (SmPC) for modafinil says the same. It states that modafinil is suspected to cause congenital malformations and should not be used during pregnancy.

What the evidence shows

The warning is based mainly on a US pregnancy registry. This is a study that follows women who took modafinil or armodafinil (a closely related medicine) around the time of pregnancy. The MHRA’s press release summed it up as an approximate 15% chance of birth defects, compared with 3% in the general population.

Source	What it found
Registry interim report, reviewed by the MHRA (2020)	78 pregnancies followed; of 61 live births, 9 had a major birth defect (about 14.75%), including 3 heart defects. Heart defects were about 4.92%, against about 1% in the general population.
Registry paper in JAMA Internal Medicine (2021)	Of 102 live births followed from early pregnancy, 13 (13%) had a major birth defect. This is above the general population rate of about 3%.
Animal studies (SmPC section 5.3)	Showed reproductive toxicity in rats and rabbits, including pregnancy loss and skeletal changes.

The evidence has limits. The registry paper by Kaplan and colleagues was small, people joined voluntarily, and there was no comparison group of unexposed pregnancies. Its authors worked for the manufacturer, and they said the data could not prove modafinil was the cause.

The UK Teratology Information Service’s bumps leaflet on modafinil notes that not all studies agree. Until more is known, it says modafinil is not recommended in pregnancy.

How modafinil affects contraception

Modafinil speeds up a set of liver enzymes (called CYP3A4/5) that break down the hormones in many contraceptives. With less hormone in your body, the contraceptive may not stop you getting pregnant.

The SmPC says the effectiveness of steroidal (hormonal) contraceptives may be reduced. It recommends other or extra methods during treatment, and for two months after stopping modafinil. The patient information leaflet names the pill, implants, intrauterine devices and patches among the hormonal contraceptives affected.

This matters twice over. Modafinil can make your contraception less reliable at the same time as it carries a possible risk to a developing baby.

Which contraception works with modafinil?

The MHRA Drug Safety Update summarises guidance from the Faculty of Sexual and Reproductive Healthcare (FSRH) for medicines like modafinil that speed up these liver enzymes. Your prescriber or a sexual health service can help you choose.

Method	What the MHRA guidance says
Combined pill, patch or vaginal ring	Avoid
Progestogen-only pill (mini pill)	Avoid
Contraceptive implant	Avoid
Copper coil (IUD)	Suitable long-term method
Hormonal coil (levonorgestrel IUS)	Suitable long-term method
Progestogen-only injection	Suitable long-term method
Condoms with your usual method	May be advised if modafinil is only used for a short time (2 months)

The NHS page on the copper coil confirms an IUD is not affected by other medicines. The patient leaflet’s list of affected contraceptives mentions intrauterine devices, so check with your prescriber which type of coil suits you.

Emergency contraception while taking modafinil

If you have had unprotected sex, tell the pharmacist or doctor that you take modafinil. The MHRA guidance says a copper IUD is the preferred option. If a copper IUD is not suitable, a double dose of the levonorgestrel emergency pill is advised, given by a pharmacist or doctor who knows about your modafinil.

The guidance recommends avoiding ulipristal acetate emergency contraception while you take modafinil. Do not change the dose of any emergency pill yourself.

The two-month rule after stopping

The effect of modafinil on your liver enzymes does not stop on the day you take your last tablet. That is why the SmPC, the patient leaflet and the MHRA all say to keep using effective contraception for two months after stopping modafinil.

The MHRA quoted Dr Sarah Branch saying that women should “continue to use their contraceptive for 2 months after stopping modafinil”. Do not switch back to a pill, patch, ring or implant alone until that time has passed and you have checked with your prescriber.

Planning a pregnancy

If you would like to get pregnant, speak to your specialist before you stop contraception. The MHRA asks prescribers to discuss pregnancy plans early and look at other narcolepsy treatment options.

Narcolepsy can also be managed with regular sleep routines and planned daytime naps, as the NHS narcolepsy treatment guide explains. Our guide to narcolepsy and excessive sleepiness covers this in more detail. Never stop or change any prescribed medicine without advice.

If you become pregnant while taking modafinil

Contact your prescriber, GP or midwife as soon as you can. Do not stop or change any medicine on your own before you have spoken to them. They can weigh up your treatment and arrange the right care.

Many babies exposed to modafinil are born without a birth defect. The bumps leaflet says you will be offered a detailed scan at around 20 weeks, possibly slightly earlier if you took modafinil in early pregnancy. A more detailed scan of the baby’s heart may also be offered.

Doctors and patients can report suspected side effects in a mother or baby linked to medicines in pregnancy through the Yellow Card scheme, as the MHRA asks.

Breastfeeding, fertility and fathers

Breastfeeding

The UK SmPC and patient leaflet say modafinil should not be used during breastfeeding. Animal studies found modafinil in milk.

Human data are very limited. The US LactMed database reports very low levels of modafinil in the milk of two nursing mothers. Talk to your specialist about feeding and treatment options before your baby is born.

Fertility

The SmPC says there are no human fertility data. In female rats, modafinil slightly increased the time to mate.

If the father takes modafinil

The bumps leaflet says no increased risk to the baby is expected if the father takes modafinil.

If you take modafinil that was not prescribed for you

Modafinil is licensed in the UK only for sleepiness caused by narcolepsy. Some people take it to try to boost focus, but it is not licensed for this. The same pregnancy risk and contraception interaction apply to anyone who takes it.

Our guide to modafinil and UK law explains its legal status. The modafinil side effects guide covers its other risks, including skin, mental health and heart effects.

This article is for information only and does not replace advice from your doctor or pharmacist. Read our medical disclaimer.