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Published on: 7/14/2026

What could be the reason for having frequent periods?

Frequent periods, medically known as polymenorrhea, occur when menstrual cycles are shorter than 21 days apart. Common causes include hormonal imbalances, starting a new birth control method, thyroid disorders, perimenopause, stress, significant weight changes, uterine fibroids, or polycystic ovary syndrome (PCOS).

Because frequent periods can stem from many different causes—some benign and others requiring medical attention—identifying the underlying reason is essential to finding relief. Rather than guessing or waiting to see if symptoms resolve on their own, take a few minutes to complete a free, instant, online symptom check. It will help you better understand what may be driving your symptoms and guide you toward informed next steps with confidence.

Reviewed for medical accuracy: 07/14/2026

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Explanation

When periods come more often than usual, it means that the time between one period and the next is shorter than what's normally expected. Your body works with hormones like estrogen and progesterone to control your menstrual cycle. If these hormones are not balanced, it can cause you to have periods more frequently. This can happen for a few reasons. For example, if you are under stress, have changes in your weight, or if you exercise a lot, your body might react by changing your normal cycle. Sometimes, underlying issues like thyroid problems or other conditions that affect hormone levels can also play a part. In college-age women, where their bodies are still learning how to balance hormones, it might happen more often. It's a good idea to keep a record of your cycle, and if you're experiencing frequent periods along with fatigue or dizziness, try our free symptom checker to better understand what might be causing your symptoms before speaking with a healthcare provider.

(References)

  • Long WN. Abnormal Vaginal Bleeding. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 173. Available from: https://www.ncbi.nlm.nih.gov/books/NBK282/

  • Adams Hillard PJ, Deitch HR. Menstrual disorders in the college age female. Pediatr Clin North Am. 2005 Feb;52(1):179-97, ix-x. doi: 10.1016/j.pcl.2004.10.004. PMID: 15748930.

  • Bae J, Park S, Kwon JW. Factors associated with menstrual cycle irregularity and menopause. BMC Womens Health. 2018 Feb 6;18(1):36. doi: 10.1186/s12905-018-0528-x. PMID: 29409520; PMCID: PMC5801702.

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