Does Cannabis Make Birth Control Ineffective?

Jessica McKeil March 2, 2020 0 comments

Cannabis is known to impact endocrine signaling, so what does this mean for the Pill.

Physicians have long warned women about smoking cigarettes in combination with birth control, especially for those over the age of thirty-five. Smoking alters hormones while also increasing the risk of heart attack and stroke. Now, with more people consuming cannabis, there are questions about its possible interactions with birth control. If cannabis impacts endocrine signaling through the endocannabinoid system, logic dictates that it may also impact birth control.

To date, there has been very little research done on the topic of cannabinoids and birth control. As is the case with most cannabis research, regulatory barriers continually prevent the kind of science needed. On top of the barriers to cannabis research, there has historically been a societal failure to investigate issues of women’s health.

The lack of study means many questions and few answers. To date, researchers have come to only a few hypotheses, largely based on endocrine signaling.

With that in mind, the following is a presentation of the facts, however tentative they are.

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How Cannabis Impacts Women’s Hormones and Endocrine Signaling

Preliminary research already indicates that cannabis consumption does impact endocrine signaling and disrupts healthy female hormone regulation.

In 2016, in the Yale Journal of Biological Medicine, Lisa K. Brent explored this topic in detail. According to her review, “Marijuana, the Endocannabinoid System and the Female Reproductive System,” cannabis consumption tends to reduce fertility by disrupting normal hormone production. For women who rely on the plant for daily treatment, this may interrupt the production of both estrogen and progesterone. Some women may even experience a disrupted cycle, and have challenges getting pregnant.

Furthermore Brent details how birth control may have a reverse effect on how women experience the intoxicating effects of THC. Studies suggest that ovarian hormones (including those found in birth control) influence tolerance and dependence to cannabis, as well as impacting the plant’s pain-relieving qualities. Brent concludes, “cannabinoids in marijuana may disrupt the delicate balance of the ECS in the female reproductive system.”

birth control which could interact with other drugs or smoking through endocrine signaling

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Cannabis Consumption and Birth Control, What We Know

Cannabis consumption does impact female endocrine signaling of the reproductive hormones, even if scientists are not entirely sure how.

So does it then upset the delicate balance created by hormonal birth controls? Hormonal birth controls, including the patch and the pill, deliver scheduled doses of both estrogen and progestin (synthetic progesterone) to control ovulation and prevent pregnancy.

It’s logical to assume, based on the little we know, that cannabis could somehow impact hormones introduced by birth control just like they affect naturally produced ones. But does science support this? Only tentatively, as there have been no studies on the subject.

First, there is some evidence showing us that THC may interrupt estrogen endocrine signaling. Presented by Shuso Takeda in his paper, “Tetrahydrocannabinol Targeting Estrogen Receptor Signaling: The Possible Mechanism of Action Coupled with Endocrine Disruption,” THC seems to have an anti-estrogenic activity.

Takeda’s paper, published in the Biological & Pharmaceutical Bulletin (2014), explains how scientists originally believed that THC might bind directly to estrogen receptors, thereby disrupting their normal function. Today, scientists have abandoned this line of study as they have found no evidence for it. Researchers like Takeda suspect that THC may impact estrogen production by interrupting the endocrine signaling between estrogen receptors. Essentially, THC could change how the different estrogen receptors communicate with one another.

Cannabis Monopolizes the Enzyme Required to Process Birth Control

Scientists have known for a few years that CBD, the non intoxicating primary cannabinoid, tends to monopolize certain metabolic enzymes. Present in the liver, metabolic enzymes are responsible for transforming digested compounds into biologically useful ones. In particular, CBD inhibits the activity of a group of enzymes called cytochrome P450 enzymes. These include CYP2C9, CYP2C19, and CYP3A4.

When the liver and the liver enzymes are flooded with CBD, they become monopolized by it and incapable of processing any other compounds until the CBD has dissipated. The problem with this situation is that the enzymes ignore all other compounds requiring transformation. Cytochrome P450 enzymes are responsible for processing roughly sixty percent of pharmaceuticals, including birth control. When not metabolized, their blood levels increase.

A study,  “Cannabinoids and Cytochrome P450 Interactions,” was published in the journal Current Drug Metabolism (2016), and discussed the evidence of this complicated enzyme interaction further. As the authors explain, “The direct activation/inhibition of nuclear receptors in the liver cells by cannabinoids may result in a change of (Cytochrome P450) expression and activity,” meaning it may impact their ability to do their jobs. Furthermore, there is a suggestion that through changing the cytochrome P450’s activity, cannabinoids may indirectly influence hormonal endocrine signaling.

Circling back to our main question on the potential impact cannabis has on birth control, research suggests that cannabis may impact the liver’s ability to metabolize birth control in a timely manner. But, this is only a very early hypothesis, and much more work is needed to flush it out.

doctor handing girl birth control, which changes her endocrine signaling

Are Women Using Birth Control at Risk by Consuming Cannabis?

What isn’t clear from all this research into cannabis and endocrine signaling is how it all would decrease the effectiveness of birth control. Most of the information available today is from extremely preliminary work with human cell lines or based on hypotheticals.

Additionally, at the time of writing, there have not even been animal trials on the subject.

The research has confirmed cannabinoids like THC and CBD do influence endocrine signaling, but how and to what effect is still up in the air. Because the reproductive cycle is based mainly on hormonal endocrine signaling, in theory, cannabis could have some effect.

So what is the good news from all this? This effect is likely small. Considering how many women are already combining birth control and cannabis, with no measurable spikes in pregnancy, the impact may only be measurable in decimal points.

References and Works Cited:

[1] Allen, Alicia M, et al. Oral Contraceptives and Cigarette Smoking: A Review of the Literature and Future Directions. Nicotine & Tobacco Research, vol. 21, no. 5, 2017, pp. 592–601., doi:10.1093/ntr/ntx258.

[2] National Academies Press. Women’s Health Research. 2010, doi:10.17226/12908.

[3] Brents L. K. (2016). Marijuana, the Endocannabinoid System and the Female Reproductive System. The Yale journal of biology and medicine, 89(2), 175–191.

[4] Takeda, Shuso. Δ9-Tetrahydrocannabinol Targeting Estrogen Receptor Signaling: The Possible Mechanism of Action Coupled with Endocrine Disruption. Biological and Pharmaceutical Bulletin, vol. 37, no. 9, 2014, pp. 1435–1438., doi:10.1248/bpb.b14-00226.

[5] Zendulka, Ondřej, et al. Cannabinoids and Cytochrome P450 Interactions. Current Drug Metabolism, vol. 17, no. 3, 2016, pp. 206–226., doi:10.2174/1389200217666151210142051.

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Jessica McKeil

Jessica McKeil is a freelance writer focused on the medical marijuana industry, from production methods to medicinal applications. She is lucky enough to live in beautiful British Columbia, Canada where the cannabis industry is exploding. When not writing, she spends much of her time exploring in the coastal forests.

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