Two Periods in One Month: How Does This Happen?

There are a few things that might lead to having two periods within four weeks.

The typical duration of menstruation is three to five days once every month. However, some people may have the experience of two periods in a month's time.

Menstruation can give you clues into what's going on with your health—and this is one problem that could be more than just picking up an extra box of tampons for the month.

When You Should—and Should Not—Be Concerned About Having Two Periods

"Just because you have two periods that happen to land within the same calendar month doesn't mean there's a problem," said Mount Kisco, New York-based ob-gyn Alyssa Dweck, MD, author of The Complete A to Z for Your V. That's because a normal menstrual cycle is between 24 and 38 days, according to the American College of Obstetricians and Gynecologists (ACOG). If your period came at the very beginning of this month and then showed up again at the end, this falls within a typical window.

If you're bleeding sooner than that or in between periods, something more might be going on with your body. A too-soon period may indicate a hormonal imbalance with estrogen, progesterone, or testosterone, which are all involved in ovulation. "This can cause irregular ovulation. Essentially, your uterus isn't sure when or how much to bleed," Dr. Dweck said. (As one example, the hormonal disorder polycystic ovary syndrome (PCOS) can cause irregular bleeding.)

Thus, here are a few other things to consider if you find that you're having another period sooner than expected.


Pregnancy is a potential cause of experiencing bleeding twice in one month. "If you're sexually active, this is one of the initial things I think about. Some women do get irregular bleeding when pregnant," Dr. Dweck said. And if you were trying for a baby, rest assured that the irregular bleeding can be totally normal and not indicative that there's something wrong. Take a pregnancy test and, if positive, call your healthcare provider; they'll let you know when they want you to come in for an appointment.

Puberty or Perimenopause

Consider your age too. During the teenage years of life, it's possible to have irregular periods after having your first one, according to the Office on Women's Health (OWH). This means that you might experience a second period in one month on occasion as your menstrual cycles start to become more regulated over time.

Perimenopause could be a possible cause if you're around or over 40 years old. Perimenopause is a time when periods are known to be irregular and you start going through the transition to menopause. "Perimenopause is a time when your hormones can be all over the place, ovulation can be sporadic, and you can get your period twice in a month," Dr. Dweck said.

Thyroid Functioning

Your thyroid, the gland that regulates your metabolism, can be another reason for your period showing up more than once. A thyroid that's over- (hyper-) or under- (hypo-) active can change up the frequency of your flow, Dr. Dweck said. In other words, if your thyroid does not make enough hormones for your body, you could have heavier bleeding; if it makes too much, you could have lighter bleeding. If those two conditions remain unregulated, you can be liable to experience not only irregular periods but multiple periods in one month.

Additional Potential Causes

Other "structural" problems, like uterine fibroids or polyps may also bring on an additional bleed, and you can have breakthrough bleeding from an IUD or hormonal birth control pills, the ACOG noted.

What To Do If You Have Two Periods In One Month

If you get your period more than once per month, contact your healthcare provider. "You can have a weird period episode, especially since stress, diet changes, travel, or exercise can cause irregularities, but if it's happening over and over, you should be seen by your doctor," Dr. Dweck explained.

They might also ask about other symptoms you may be experiencing along with the multiple instances of menstruation and run additional testing—blood work, ultrasound, etc.—depending on what's suspected. After that, the underlying cause will inform treatment, whether it's thyroid medication, a new birth control method, or a plan for managing PCOS.

Figuring out why you're dealing with two periods in one month isn't always so cut and dry, but knowing why you might be having this experience can give you a better idea of what's going on.

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