Does Melatonin Affect Birth Control? What Experts Want You to Know

Does melatonin 'cancel out' birth control? We asked multiple Canadian experts and it turns out, the answer isn't a simple "yes" or "no."

The first time I told a friend I was considering the birth control pill to help with my painful periods, she responded that “the pill” was rumoured to cause infertility. For the record, research has shown no link between the birth control pill and infertility. This is just one of the many pervasive misconceptions about how birth control pills can affect the body.

Birth control pills have been available in Canada for more than 50 years. The hormonal medication is typically a combination of estrogen and progesterone that prevents pregnancy by safely stopping ovulation. According to a 2015 survey by Statistics Canada, an estimated 1.6 million women in Canada between the ages of 15 and 49 use or have used oral contraceptives—and yet these myths about these medications persevere.

One such concern is about taking the birth control pill while also taking melatonin pills. Melatonin is a hormone that helps the body adjust to the time of day and seasons. Though this hormone occurs naturally in the body, in recent years, melatonin has become a popular over-the-counter supplement to help regulate the sleep cycle. But the question is: Can taking melatonin to catch some zzzs affect how well birth control pills work?

To clear up any confusion, we asked Canadian medical experts whether melatonin can cancel out birth control. Here’s what they had to say.

(Related: What’s the Best Way to Switch Birth Control Pills?)

How do medications interact with birth control?

There are some medications that can interact with the birth control pill and lessen its efficacy at preventing unwanted pregnancy. “The ones that most commonly come to mind are anti-epileptic medications,” says Dr. Constance Nasello, an ob-gyn in Chatham, Ontario.

Nasello explains that the birth control pill and some epilepsy drugs use the same enzyme system in the liver to break down the pill. “Whenever we take a medication that needs an enzyme system, our body actually increases those enzymes to help with the breakdown,” says Nasello. “If there’s another medication that uses the same enzyme system, then you might have decreased effectiveness.”

Basically, some seizure medicines can lower the levels of progesterone and estrogen provided by the birth control pill, increasing your chances of ovulation and pregnancy.

So, can melatonin ‘cancel out’ the birth control pill?

According to Dr. Marjorie Dixon, CEO and medical director at Anova Fertility and Reproductive Health in Toronto, the pill and melatonin supplements may interact with each other, but the mechanism behind this “isn’t exactly clear.”

“There are some concerns that melatonin supplements may decrease birth control’s effectiveness, although there is not much research available on this topic yet,” Dixon says. “The idea is that if melatonin and birth control are both metabolized by the liver, the liver must work ‘overtime’ to activate both compounds.”

The potential drug interaction is similar to how some antibiotics—like rifampicin, a medication commonly used for tuberculosis—can decrease the effectiveness of the birth control pill. However, due to the lack of research on melatonin’s interaction with the birth control pill, Dixon recommends that users err on the side of caution.

“If you are taking melatonin supplements, make sure to mention this to your doctor to ensure that you’re protected from unwanted pregnancy,” Dixon says. “If you are currently on the birth control pill, you may want to consider switching to long-acting reversible contraception (LARC) such as the IUD, which is not metabolized by the body.”

Talk to your doctor

Because the research on interactions between medications is always evolving, it’s crucial to talk to your doctor and your pharmacist about the medications you’re currently taking before accepting a new prescription. That discussion should also include any supplements.

“We need to get your medical history, allergies and what medications you’re taking, because those [play a very important role] in what we prescribe,” says Nasello.

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