Short answer? Cannabis probably doesn’t interfere with HRT.
We can’t start an article on cannabis without starting by acknowledging the ways in which Black and brown communities have been disproportionately penalized for this incredibly helpful plant. Two-thirds of Americans support legalizing marijuana, but historically “Black people are 3.64 times more likely than white people to be arrested for marijuana possession.” We believe an important part of cannabis consumption is doing so responsibly and aware of the system: this Ben & Jerry’s (seriously) resource is massively helpful.
The two main components of cannabis are:
Without getting deeper into the makeup of the plant, what’s important to know in this context is that all bodies process THC and CBD differently. Along these lines, while all bodies produce estrogen and testosterone, bodies on hormone replacement therapy (HRT) are receiving additional hormones than those that they create, while also potentially blocking existing hormones and hormone dependent organs in the body. Because the body is processing multiple things at once (THC & CBD, hormones), we’ve gotten questions about whether there’s any interaction or interference between weed and HRT specifically.
The short answer is: likely no.
The long answer is: we don’t actually have a ton of information about the interactions of cannabis and hormones. Most of what we know is based on studies with animals or studies done in the 1980s. And very little research has been done with humans, let alone trans folks specifically.
The majority of research in humans suggests that people assigned female at birth are more likely to be affected by cannabinoids than people assigned male at birth. Again, without much research it’s hard to say anything super conclusive, but what we can get from this is that taking hormones may cause a change in how their body reacts to cannabis because of new levels of estrogen and testosterone.
In studies of rodents, females have been found to be more sensitive than males to effects of cannabinoids on tests like sensitivity to pain or movement activity. According to Dr. Rebecca Craft, a psychologist researching cannabis and the endocrine system at Washington State University, “Several pieces of evidence point to estrogens — estradiol in particular, which is the major estrogenic hormone in both rats and humans — as the hormone that makes females more sensitive than males to some effects of THC.” In researching male rats with their testes removed and then treated with estradiol, their sensitivity to THC’s pain-relieving effects started to resemble that of female rats. But this same trend doesn't apply for all effects of THC in rats. With the sleepiness typically caused by indica-dominant strains of cannabis, estradiol has no impact; rather, males with higher testosterone levels are more affected. In short: the differences in the levels of rats’ hormones saw a change in response to cannabis.
A 2018 Merry Jane article goes deeper into different individual’s experiences with changing hormone levels and their reactions to cannabis, as well as the rat hormone research.
For people born with sperm-producing organs, there are studies showing a decrease in sperm count from weekly cannabis use. One 2015 study looked at 1,215 young Danish people with penises aged between 18 and 28 years and found that regular cannabis smoking (more than once a week) was associated with 28 percent lower sperm concentration and a 29 percent lower total sperm count. People on estrogen already may see a decrease in sperm production, which makes this a particular consideration for those interested in family planning.
For people born with egg-producing organs, there’s only been one good study that shows cannabis can cause some delay in ovulation. Testosterone also affects the way existing hormones, specifically those in charge of menstruation and ovulation, function within bodies in ways that can make someone less fertile. The combination of testosterone and cannabis on fertility in menstruating bodies is a consideration for those who may be looking to get pregnant someday.
Ultimately: we have VERY minimal good quality research on cannabis, largely due to federal regulations. And we still have minimal good quality research on trans and nonbinary people. All this is to say we can’t make any hard and fast statements on cannabis and HRT, but we can continue to learn from our community’s experience.
Lastly: FOLX members shouldn’t hesitate to speak to their clinicians about cannabis use in regards to their overall health and HRT!