Does calcium help with irregular periods during perimenopause?

Calcium is not an effective treatment for irregular periods during perimenopause, and the evidence connecting calcium supplementation to menstrual cycle regulation is very limited. Irregular bleeding in perimenopause is driven by erratic ovulation and fluctuating estrogen and progesterone levels, which are hormonal events that calcium cannot meaningfully influence. If your periods have become unpredictable in timing, length, or flow volume, the cause is almost certainly the underlying hormonal transition of perimenopause rather than a calcium deficiency.

Where calcium does have some research backing in a menstrual context is premenstrual syndrome, specifically the mood and physical symptoms that occur in the luteal phase before the period, not cycle regularity itself. Several randomized trials have found that calcium supplementation reduces emotional and physical PMS symptoms including mood changes, bloating, cramping, and food cravings in reproductive-age women with regular cycles. A well-cited randomized trial published in the American Journal of Obstetrics and Gynecology found that 1,200 mg of calcium carbonate per day significantly reduced overall PMS symptom scores compared to placebo. The proposed mechanism involves calcium's role in neurotransmitter regulation and its relationship with estrogen, which influences how the body manages calcium levels across the menstrual cycle. That PMS finding is one of the more solid pieces of evidence for calcium in a menstrual context, but it does not extend to regulating cycle timing or reducing perimenopausal irregularity.

In perimenopause, the hypothalamic-pituitary-ovarian axis becomes increasingly unpredictable. Ovulation may be skipped entirely in some cycles, leading to prolonged estrogen stimulation of the uterine lining without the balancing effect of progesterone. In other cycles, ovulation occurs but progesterone production is insufficient to maintain the lining properly. These hormonal shifts cause the irregular timing, heavier or lighter flow, prolonged spotting, or missed periods that many women experience in this transition. Calcium does not influence ovulation, progesterone secretion, or the hypothalamic signaling that drives cycle regularity. No over-the-counter supplement does this reliably, and any supplement claimed to regulate cycles in perimenopause should be viewed skeptically.

For general bone health during perimenopause, which is the well-supported reason to maintain adequate calcium intake, women 51 and older need 1,200 mg of calcium per day from all sources combined. Studies have generally used supplemental doses of 500 to 600 mg taken twice daily with food to avoid hitting the absorption ceiling in a single dose. The tolerable upper intake level from food and supplements combined is 2,500 mg per day. Staying below that limit matters because excess calcium has been associated in some large observational studies with kidney stones and possible cardiovascular risk. Calcium carbonate is widely available and works well when taken with meals. Calcium citrate is absorbed with or without food and is a better choice if you have digestive sensitivity or take acid-reducing medications. Talk to your healthcare provider about the right dose and form for your situation.

Calcium competes with iron for intestinal absorption, which is relevant because irregular or heavy perimenopausal bleeding can significantly deplete iron stores over time. Take these two supplements at least two hours apart. If you take thyroid medication, take calcium at least four hours away from your thyroid dose because calcium impairs levothyroxine absorption. Calcium also interferes with bisphosphonate bone medications and some antibiotics. Always check with your provider if you take any prescription medications before adding or increasing calcium.

If you do take calcium as part of a broader perimenopause supplement routine, give it eight to twelve weeks before evaluating any change in how you feel. Keep in mind that cycle variability in perimenopause fluctuates on its own accord over months, so distinguishing a supplement effect from natural variation is genuinely difficult without careful, consistent tracking. Note the start date, length, and heaviness of each period alongside mood, energy, and other symptoms to build a useful longitudinal record.

See a doctor about irregular bleeding if a period lasts longer than seven days, if you are soaking through a pad or tampon in an hour or less for two or more consecutive hours, if you experience bleeding after sex, if you spot between periods regularly without an obvious hormonal cause, or if you go more than three months without a period before reaching confirmed menopause. Abnormal bleeding warrants evaluation to rule out endometrial polyps, fibroids, or less commonly endometrial hyperplasia or cancer. Not all irregular bleeding in this life stage is from perimenopause alone, and a pelvic ultrasound or endometrial biopsy may be appropriate depending on your symptom pattern.

The PeriPlan app lets you track period start and end dates, flow heaviness, and associated symptoms month after month, building the kind of longitudinal record that helps your provider distinguish normal perimenopausal variability from patterns that warrant further investigation. Consistent tracking over three to six months reveals far more than any individual cycle can tell you on its own. Find PeriPlan at https://apps.apple.com/app/periplan/id6740066498

This content is for informational purposes only and does not replace medical advice. Always consult your healthcare provider about your specific situation.