Does Weed Affect Your Period? 5 Ways Cannabis May Change Your Menstrual Cycle

Yes, cannabis can affect your menstrual cycle: research suggests THC may interfere with ovulation, shift cycle length and possibly embryo implantation, while many people report that weed eases period cramps and PMS. Most of the evidence comes from small or older studies, often in animals, so none of it is settled. Here are five ways cannabis and your cycle may interact.

People who use cannabis often report changes in their period, and science is just starting to dig into those observations to figure out what's going on underneath.

Understanding these interactions gives a clearer picture of how cannabis affects women's health and helps you make informed decisions about using it.

1. THC may reduce fertility around ovulation

Plenty of studies have looked at the link between the endocannabinoid system and the female reproductive cycle, and they show that levels of anandamide, the body's key endocannabinoid, swing a lot over the course of the menstrual cycle.

Notably, anandamide peaks at ovulation, when the ovary releases an egg. Since anandamide is a cannabinoid receptor agonist (it switches those receptors on), you'd expect high THC levels, another agonist, not to mess with ovulation.

But research from the 1970s and '80s suggests that THC in particular can block ovulation in several mammals, primates included, although it hasn't been specifically studied in humans. THC seems to do this by suppressing luteinizing hormone (LH), which is crucial for ovulation.

Worth noting: regular cannabis users may build up a tolerance to THC's ovulation-blocking effect. Still, more research is needed to pin down the actual link between cannabis use and ovulation in women.

2. Cannabis may ease period cramps and pelvic pain

Cannabis has been used in traditional medicine across many cultures as a remedy for dysmenorrhea, the medical term for painful periods. A famous (and unconfirmed) story says Britain's Queen Victoria used cannabis for her menstrual cramps under the supervision of her personal physician, Sir John Russell Reynolds, an early advocate of medical cannabis.

Today, plenty of people still reach for cannabis to deal with period pain and report noticeable relief.

There aren't formal studies backing its effectiveness and the exact biology hasn't been mapped out, but THC is known to have strong analgesic and antinociceptive effects.

Analgesics are general painkillers, while antinociceptives keep nerves from picking up pain signals in the first place. On top of that, both THC and CBD have anti-inflammatory properties, which may help take the edge off.

If you want pain relief without THC's high, CBD may be a good fit.

3. Cannabis may suppress key hormones before your period

During the premenstrual phase, also called the luteal phase, hormonal swings can bring a whole range of symptoms: pain, irritability, mood swings, fatigue and bloating.

In this phase, certain hormones like progesterone rise significantly, while others, like estrogen, drop.

When those symptoms get unusually severe, doctors call it premenstrual syndrome (PMS). Traditionally, physicians prescribed supplemental progesterone for severe PMS, but more recent research shows that treatment doesn't always work.

The general consensus is that abnormal premenstrual symptoms are tied to low progesterone at a time when it should be high. That said, some PMS symptoms seem to be associated with too much progesterone and reduced estrogen.

How weed may affect the premenstrual phase

What's clear is that severe premenstrual symptoms, the kind that qualify as PMS, come from hormonal swings and imbalances. There's also evidence that cannabis use can have several effects during the luteal phase, the stretch between ovulation and the start of your period.

Cannabis use may:

• Suppress progesterone levels.
• Alter levels of other important hormones, like prolactin and cortisol.
• Blunt THC's own effect on luteinizing hormone.

The specific mechanisms haven't been fully worked out, but the endocannabinoid system clearly plays a big role. People with unusually rough symptoms in this phase might benefit from cannabinoid-based therapies, though that still needs proper study.

In fact, lots of people around the world report feeling better when they use cannabis during the premenstrual phase. That relief may come from cannabis's well-known relaxing and anti-anxiety effects rather than any direct effect on hormone levels.

4. THC may shorten your menstrual cycle

Current research suggests THC might shorten the menstrual cycle. In a 1986 study on THC and luteinizing hormone, women who were given cannabis had shorter cycles overall than women given a placebo.

What primate studies show

Interestingly, older primate studies found THC can change cycle length, but not necessarily shorten it. A 1980 study in rhesus monkeys found females treated with THC had significantly longer cycles. In one case, a monkey's cycle stretched to 145 days, compared with the usual 30.

Why we need more research

Clearly, more research is needed to understand whether, and how exactly, THC affects cycle length in women. As with THC's ovulation-blocking effect, regular users may quickly develop a tolerance to any effect on cycle length.

5. THC may affect embryo implantation in the uterus

Over the past decade, several studies have looked at how the endocannabinoid system shapes key steps in conception and early pregnancy.

These studies show that anandamide levels shift significantly across the menstrual cycle and hit their lowest point during the "implantation window."

What is the implantation window?

The implantation window is the period when an embryo can successfully implant in the endometrium, the lining of the uterus. It usually opens 6 to 10 days after ovulation and lasts about three days.

How THC could affect implantation

In studies where anandamide was artificially raised during this stage, implantation didn't happen. Since both anandamide and THC activate cannabinoid receptors, it's tempting to assume that using THC during the implantation window could have a similar effect. But that's an oversimplification that doesn't necessarily hold up in a system as complex as the endocannabinoid system.

What to do if you're trying to get pregnant

More research is needed to confirm whether high-THC cannabis can block a fertilized egg from implanting during the implantation window.

Until then, to play it safe, if you use cannabis and are trying to get pregnant, consider taking a break from cannabis at least 24 hours before your implantation window opens, and talk it over with your doctor.

Bottom line: how weed affects your menstrual cycle

THC may have several effects on the menstrual cycle, including possibly shortening it and interfering with embryo implantation. Research is ongoing and more evidence is needed to confirm these effects, but if you're trying to get pregnant, keep these possible implications of cannabis use in mind.