Two periods in one month can happen from short cycles, stress, or hormones. See a doctor if it keeps happening.
Possible causes
- Short cycles (21 days or less).
- Stress.
- Hormonal birth control.
- PCOS or thyroid disease.
- Perimenopause.
- Ovulation bleeding.
Normal cycle
21 to 35 days, so two periods in one month can occur.
Is it a period
Check whether bleeding is true menstruation or spotting.
See a doctor
If it happens repeatedly or bleeding is heavy.
Cycle math
A cycle of 21 to 24 days can fit two periods into one 30 or 31 day calendar month. For example, a period on the 1st and the 25th, followed by another on the 19th of the next month, is still regular if the cycle is consistent.
Normal cycle length
ACOG defines normal cycles as 21 to 35 days in adults, with bleeding lasting up to 7 days. Teens have a range of 21 to 45 days.
Causes of extra bleeding
- Short cycles, especially in the first years after menarche or in perimenopause.
- Anovulatory cycles.
- Hormonal birth control changes and breakthrough bleeding.
- Polycystic ovary syndrome.
- Thyroid problems.
- Uterine fibroids, polyps or adenomyosis.
- Infections such as pelvic inflammatory disease.
- Early pregnancy loss or ectopic pregnancy.
- Stress, weight change or intense exercise.
- Blood thinners.
Ovulation spotting
Light spotting around mid cycle is not a second period.
Period or something else
A true period involves a flow that lasts several days, typically needing pads or tampons. Spotting is lighter, shorter and often brown or pink.
What to do
- Track the dates, flow and associated symptoms.
- Take a pregnancy test if a period is late or unusual.
- See your doctor to check hormone levels, thyroid function, and perform a pelvic ultrasound if bleeding persists.
Treatment
Depends on the cause and might include hormonal birth control, medicines for fibroids or polyps, treating infections or adjusting thyroid treatment.
See a doctor if
You bleed more than twice a month for several cycles, soak through a pad or tampon every hour, have severe pain, dizziness, fever or you might be pregnant. Anemia from heavy bleeding can cause fatigue and weakness.
Cycle length and causes
A cycle of 21 days can lead to two periods in one calendar month, which can be normal if it is regular. Bleeding twice in a month at irregular times may result from anovulatory cycles, perimenopause, thyroid disease, polycystic ovary syndrome, stress, major weight changes, hormonal contraceptives and missed pills. Uterine polyps, fibroids, infections and pregnancy complications such as miscarriage or ectopic pregnancy can cause extra bleeding. Mid cycle spotting at ovulation can look like a second period.
What to do
Track the start date, flow and symptoms for several months. Take a pregnancy test if sexually active. See a doctor if cycles are shorter than 21 days, bleeding is heavy (soaking a pad in an hour), lasts over 7 days, occurs after sex or between periods repeatedly, or comes with severe pain or dizziness. A doctor may do an exam, blood tests and an ultrasound, and treatment can include hormones or procedures. Seek urgent care for heavy bleeding with fainting or severe pelvic pain.
Based on data from ACOG and the Mayo Clinic
