HRT and digestion: 6 myths and the facts

Hormone therapy attracts strong opinions, and a surprising number of them involve your stomach: that progesterone will back you up, that any digestive side effect means you have to quit, or that your gut has nothing to do with the decision at all.

First, some context. The North American Menopause Society, now called The Menopause Society, concluded in its 2022 position statement that hormone therapy remains the most effective treatment for hot flashes and night sweats. For women younger than 60 or within 10 years of menopause who don't have reasons to avoid it, the benefits generally outweigh the risks for these symptoms and for preventing bone loss (North American Menopause Society, 2022). With that in mind, here's how six common beliefs about hormones and digestion hold up.

Myth 1: Hormone therapy has nothing to do with your gut

Fact: The gut responds to sex hormones, and hormone therapy is no exception. In a Mayo Clinic study, 49 postmenopausal women were randomly assigned to one week of micronized progesterone, estradiol, both, or placebo. Both estradiol and progesterone led to looser stools compared with placebo (Gonenne et al., 2006).

That doesn't mean every woman will notice a change. It means shifts in bowel habits after starting hormones are plausible and worth tracking, not imagined.

Myth 2: The progesterone part will make you constipated

Fact: Progesterone has a reputation for slowing the gut, largely because digestion can slow in the high-progesterone half of the menstrual cycle. But in the same Mayo Clinic study, micronized progesterone did not slow movement through the colon in postmenopausal women. Some measures of colon transit were actually faster. Estradiol, alone or combined, didn't change transit either, and stopping the hormones afterward didn't cause a significant change (Gonenne et al., 2006).

The study was small and lasted only a week, so it can't rule out effects over months of use. But it's a useful counterweight to the assumption that progesterone always means constipation.

Myth 3: New gut symptoms on HRT can't be connected

Fact: There may be a link, though it isn't proven. A UK study compared 40,119 women aged 50 to 69 who were prescribed hormone therapy with 50,000 women of similar age who never used it. New diagnoses of irritable bowel syndrome (IBS) occurred at 3.8 per 1,000 person-years among hormone users, compared with 1.7 among never-users. The higher risk showed up regardless of how long women used hormones, the regimen or the route (Ruigómez et al., 2003).

The researchers adjusted for other health conditions and for how often women saw their doctors, but an observational study like this still can't show that hormones caused IBS. The practical takeaway: if your digestion changes after starting hormone therapy, tell your prescriber. Don't assume it's unrelated, and don't assume it's permanent.

Myth 4: The gallbladder risk is just a theory

Fact: It was confirmed in randomized trials. In the Women's Health Initiative, 22,579 women aged 50 to 79 took estrogen alone, estrogen plus progestin, or placebo. Gallbladder events occurred at 78 per 10,000 person-years with estrogen alone vs. 47 with placebo, and at 55 vs. 35 in the combined-hormone trial. Both hormone groups were more likely to need gallbladder removal (Cirillo et al., 2005).

These trials tested one specific regimen, conjugated equine estrogens with or without medroxyprogesterone acetate, so the numbers don't automatically apply to every product. But the direction of the effect is clear.

Myth 5: Pills and patches are the same for your gut

Fact: The route appears to matter for the gallbladder. The Million Women Study followed more than one million postmenopausal women in the UK. Compared with never-users, current users of oral hormone therapy had a relative risk of 1.74 for hospital admission for gallbladder disease, while transdermal users had a much smaller increase (1.17). Over five years, gallbladder removals occurred in 1.1 of every 100 never-users, 1.3 of every 100 transdermal users and 2.0 of every 100 oral users. Higher estrogen doses carried more risk, and risk fell after stopping (Liu et al., 2008).

The authors estimated that choosing transdermal over oral therapy for five years could avoid one gallbladder removal for every 140 women. If you have a history of gallstones, the route is a good question to raise with your prescriber.

Myth 6: Any digestive side effect means HRT isn't for you

Fact: Hormone therapy isn't one fixed thing. According to The Menopause Society's position statement, risks differ by type, dose, duration of use, route, timing of initiation and whether a progestogen is used, and treatment should be individualized and periodically reevaluated (North American Menopause Society, 2022).

So a digestive side effect is a reason to talk with your prescriber about adjusting the plan, not necessarily a reason to give up on symptom relief. Keep a simple two-week log of stool changes, bloating and any upper abdominal pain before that conversation.

When to call your doctor promptly

• Episodes of strong pain in the upper right or upper middle abdomen, especially after meals
• Pain with fever, or yellowing of your skin or eyes
• Blood in your stool, black stools or unexplained weight loss
• New bloating on most days, especially with early fullness, pelvic pain or urinary urgency
• Any new vaginal bleeding after menopause

Sources

1. The 2022 Hormone Therapy Position Statement of The North American Menopause Society Advisory Panel. The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767-794. PMID 35797481
2. Gonenne J, Esfandyari T, Camilleri M, et al. Effect of female sex hormone supplementation and withdrawal on gastrointestinal and colonic transit in postmenopausal women. Neurogastroenterol Motil. 2006;18(10):911-8. PMID 16961694
3. Ruigómez A, García Rodríguez LA, Johansson S, Wallander MA. Is hormone replacement therapy associated with an increased risk of irritable bowel syndrome? Maturitas. 2003;44(2):133-40. PMID 12590009
4. Cirillo DJ, Wallace RB, Rodabough RJ, et al. Effect of estrogen therapy on gallbladder disease. JAMA. 2005;293(3):330-9. PMID 15657326
5. Liu B, Beral V, Balkwill A, Green J, Sweetland S, Reeves G. Gallbladder disease and use of transdermal versus oral hormone replacement therapy in postmenopausal women: prospective cohort study. BMJ. 2008;337:a386. PMID 18617493

This article is for general information and isn't medical advice. Decisions about hormone therapy should be made with your healthcare provider, and you shouldn't stop or change a prescription without their guidance.