Our periods can bring on a slew of not-so-great symptoms, like the mental and emotional side effects of PMS, that monthly jawline breakout, and painful cramps. Many women also experience digestive issues like gas, bloating, diarrhea, and constipation during their period.

On a basic level, your period happens due to fluctuations in hormone levels, which cause the uterus to shed excess lining or tissue. But why does our stomach seem to go haywire at the same time? After all, it’s a totally different part of the body. We talked to Stefani Davis, a Women’s Health Nurse Practitioner (WHNP), to find out.

First things first: you’re normal

Davis reassured us that it’s totally normal to struggle with your stomach during your period. “Digestive issues during your period are really common,” she said. “Helping my patients understand that this is a common complaint among women and being open about the causes helps alleviate anxiety that they may be experiencing something abnormal.”

But, Davis warned that those of us with underlying gastrointestinal issues may be more susceptible to digestive problems during our periods. “Women with irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) sometimes experience worse symptoms than women who don’t have a GI disorder.”

So what’s the culprit?

As it turns out, the chemicals and hormones that trigger our periods are likely responsible for our stomach woes, too. But, as Davis pointed out, it’s important to understand that there’s actually not a lot of research in this area.

“While the exact science behind why digestive problems surface [during your period] is unknown, it’s reasonable to blame the hormones,” she said. “The fluctuations, or rises and falls, of estrogen, progesterone, and prostaglandins during your cycle also cause changes in the muscles of the GI tract, which control digestion.”

Why hormones impact your stomach

“Estrogen and progesterone are the two hormones that regulate your menstrual cycle, while prostaglandins are a lipid, or fat, compound that actually act like a hormone in the body,” said Davis. “Like estrogen and progesterone, your level of prostaglandins also fluctuate during your period.” She explained there are different types of prostaglandins in the body, and one is specific to the female reproductive system. The amount of reproductive prostaglandins is what fluctuates during your period.

“While it’s not known exactly why the GI tract is sensitive to hormonal changes throughout a woman’s cycle, it is known that there are sex hormone receptors located along the GI tract,” said Davis. So, the presence of sex hormone receptors in the GI tract is the reason why experts think women experience digestive issues during their period. Receptors interact with the hormones, and regulate certain physical responses to the hormones. Davis explained, “Progesterone is well known for causing constipation during pregnancy by slowing the motility, or the contraction of muscles, of the GI tract. On the other hand, estrogen tends to enhance GI motility, and can be to blame for diarrhea.”

When asked about prostaglandins, Davis said, “Prostaglandins specific to the female reproductive system play a role in the contraction of uterine muscles, which can cause pelvic cramps. Because there are also sex hormone receptors along the GI tract, as there are in the uterus, we think prostaglandins can potentially impact muscles in the GI system, too, which leads to bloating, diarrhea, and constipation.”

Ways to start feeling better

“Some women may benefit from hormonal contraception, like birth control pills or a hormonal IUD, to help decrease the hormonal fluctuations that contribute to digestive issues,” said Davis. But for those of us that may also be struggling with IBS or IBD, it’s important to get treated for these specific digestive issues by a specialist first.

Davis also recommended keeping a journal. “Write down and keep track of symptoms, diet, and physical activity to determine if certain triggers, like a type of food, worsen symptoms. From there, try to eliminate or avoid those triggers right before and during your period.”

A need for more research

Davis emphasized that there’s still a lot of research needed on this topic. “Honestly, further research needs to be done to determine the true reason behind what causes digestive issues during women’s periods. But, right now, hormones are the most likely explanation. Anything you can do to manage their fluctuation during your period is your best bet, whether it’s hormonal contraception or taking careful note of what you’re eating or doing [and how that affects your symptoms].”

Even if you choose not to pursue these recommended routes, don’t forget, there’s nothing unusual or unnatural about your symptoms. Though period symptoms can sometimes make us feel out of whack, it’s completely normal to struggle with digestive issues during your period.

English Taylor is a health and wellness writer living in San Francisco. Her work has been featured in Nylon, Refinery29, and The Atlantic. English enjoys spending time with her friends, family, and 150-pound dog named Bubbles. Her favorite foods are peanut butter and pickles (sometimes together).