To cover our rear, ask your doctor or pharmacist! Follow their advice. Thus for educational purposes, and not as medical advice, we point out that many women in the United States will use some form of birth control in their lifetime1. One of the most common forms is hormonal birth control pills also called oral contraceptive pills. With cannabis becoming legal and increasingly available in the United States, it is important to ask whether and how the two may adversely interact.
While we don’t know exactly how cannabis and oral contraceptive birth control pills interact, by looking at the existing research we can draw some conclusions about two different aspects: how interactions could potentially make birth control less effective or increase unwanted pregnancies, and how cannabis use could produce or exacerbate negative side effects if you’re using birth control pills.
Does cannabis make birth control less effective?
The short answer is not directly via drug-drug interactions for other than possibly very high dose users. However, if a woman of childbearing age is taking over 200 mg a day of THC or over 600 mg a day of CBD, we don’t know!
Before getting into why, let’s first address the most obvious assertion about cannabis and birth control which also doesn’t need any peer reviewed research. Cannabis can certainly make birth control less effective — if it makes you forget to take your birth control pills or barrier methods (sponge, condoms) or if disinhibition leads to any behavior that risks pregnancy. Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include: phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St. John’s wort.
Beyond that, on a scientific level, we need to first look at how hormonal birth control methods work. There are many different types of hormonal birth control ranging from pills to patches to shots. They mainly work by using a combination of the hormone estrogen and progestin (a synthetic version of the steroid hormone progesterone) to affect a woman’s hormone levels and prevent the ovaries from releasing mature eggs by making the body think it is pregnant2. Some forms of hormonal birth control, other than oral contraceptive pills, can also prevent sperm from penetrating the cervix.
While the effect on humans is largely unknown, research performed on monkeys has provided evidence3 that marijuana can lead to reduced estrogen levels and reduced progesterone4 — the steroid hormone that regulates the menstrual cycle and helps prepare the body for conception and pregnancy.
The endocannabinoid system and birth control
Research has found a strong link5 between the endocannabinoid system and the functioning of the female reproductive system. The ECS is a system in the bodies of all vertebrates that helps modulate basic functions ranging from appetite to mood to reproductive health. The ECS is activated by cannabinoids that exist naturally in the body, called endocannabinoids, but also by cannabinoids found in cannabis — phytocannabinoids.
Research has shown that endocannabinoids have a very important role in the female reproductive system, and that impairment of the ECS can harm the functioning of female reproductive organs and increase infertility6.
As one comprehensive review of research from 2012 noted, “almost all pregnancy events are regulated by endocannabinoid signaling, and in most cases, optimal outcomes can only be achieved under normal physiological endocannabinoid levels. Either silenced or enhanced endocannabinoid signaling derails these processes.”7
Because the system is altered by some of the cannabinoids found in marijuana, this may suggest that cannabis can have a detrimental — or potentially positive — effect on female reproductive health, though more research is needed to get a clearer picture of how cannabis use can affect estrogen and progesterone levels, and how this could impact the efficacy of hormonal birth control.
Can you smoke weed while on birth control?
Smoking anything while using birth control is widely considered to be harmful, in that both smoking and hormonal birth control can have some of the same potential cardiovascular side effects. While still rare, hormonal birth control can make women more likely8 to develop blood clots, which can lead to other health issues, such as deep vein thrombosis, pulmonary embolism, or even heart attack or stroke.9
A 2013 Vanity Fair article about the NuvaRing contraceptive stated that the FDA had determined it had a 56% increased risk of blood clots over earlier birth control pills.
A 2020 study found that THC increased the risk of thromboembolic complications in trauma patients10, while other studies have produced conflicting findings regarding whether cannabis use can increase the risk of ischemic stroke — a stroke caused by a blocked blood vessel (for instance, by a blood clot).
The fact that smokers have been found to have coagulation abnormalities is one of the reasons that doctors have long recommended that women who are using birth control should cease smoking cigarettes.11
This would suggest that cannabis smoking could also be a risk factor for women who are using birth control, because of how it affects the cardiovascular system. At the same time, like with strokes, researchers have found conflicting results regarding whether cannabis could reduce blood pressure — or increase the risk of developing hypertension — or both.
Is CBD oil bad for birth control?
With the soaring popularity of CBD wellness products, it’s no surprise that many women and their partners may wonder if cannabidiol could have an adverse effect on the efficacy of birth control.
Like many other aspects of cannabis and birth control, the research into how CBD affects hormones12 is still scarce, though more research has gone into how it affects pregnancy.
Among the research that has been performed, a 2019 in vitro study found that cannabinoids do not directly activate estrogen receptors, although it was not performed on human subjects. This could indicate that CBD and other cannabinoids are less likely to have an effect on how hormonal birth control works.
There is also the matter of how CBD and other cannabinoids interact with the liver, which is responsible for metabolizing drugs like birth control. Some research has indicated that in high doses, CBD could potentially cause liver damage — in rodents — but it is unclear if this can be applied to humans as well, or if it means that CBD could affect the liver’s ability to metabolize birth control.
Your best bet is to speak to your physician regarding whether or not you should stop taking CBD while on birth control.
Cannabis to treat the side effects of birth control
While the science on how cannabis affects birth control may still be lacking, there is more evidence about how cannabis can treat some of the more common side effects13 of hormonal contraceptives.
Many women who use hormonal contraceptives report experiencing nausea. The endocannabinoid system regulates nausea, which is one of the reasons that cannabis can be very effective as an anti-nausea treatment. It can also be a more effective and safer option than more traditional anti-emetics, though this is by no means true for every medical cannabis patient or for every type of nausea. Very low doses of THC, with barely perceptible psychoactive effects, may prevent or treat nausea and vomiting.
Headaches and migraines
Research has shown that women who use hormonal contraceptives may experience headaches and migraines14. Cannabis can provide some patients relief from migraines and other types of headaches. Pain relief is in many states the number one reason that patients are recommended medical cannabis.
Hormonal contraceptives can have a serious impact on the user’s mood and mental state and can increase feelings of depression and anxiety. While for some people cannabis can actually exacerbate mental health problems, it can also help provide relief from depression and anxiety. To be on the safe side though, anyone dealing with serious mental health difficulties, including addiction, should speak to a counselor or therapist, and may want to also consult their physician or psychiatrist before turning to cannabis for relief.
The bottom line
There is still not enough scientific evidence to say for certain if cannabis reduces the efficacy of hormonal birth control, or if using cannabis while on birth control can pose its own risks. The lower the dose of cannabis the lower the risk of drug-drug interaction.
Regardless, birth control can cause a number of unwanted side effects for women and if you are curious whether you should abstain from cannabis while using hormonal contraceptives, consider speaking to a qualified health care professional.
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