The thought of having two periods in one month might make you scowl as you think about double the amount of tampons, pads, cramps, and potentially ruined underwear to deal with. It also comes with the challenge of experiencing hormonal fluctuations again, which can cause PMS symptoms like fatigue, bloating, and irritability. But the truth is it's a lot more common than you might think.

And if you're wondering what bleeding looks like when it happens twice a month, Lorraine Chrisomalis-Valasiadis, MD, a New York City-based ob-gyn, says that it's possible to have two normal cycles with the same kind of bleeding or you can have normal flow during one and spotting during the other. Ultimately, it depends on the cause.

If you have an underlying condition that's causing two periods per month, keep this in mind: "Irregular bleeding can have different implications depending on age, medical history, and family history," says Alyssa Dweck, MD, an ob-gyn and the author of The Complete A to Z for Your V. "So it's important to seek ob-gyn guidance if you have persistent, recurrent, or worrisome bleeding habits."

Before you freak out though, know that getting your period more than once a month can also just be a matter of genetics and completely harmless (other than the discomfort). In other words, it's not something you need to worry about. "There are some women that have cycles every 21 days, and that's normal. And there are others that have cycles every 40 days, and that's normal," Dr. Chrisomalis-Valasiadis explains. "So, some women just have cycles every three weeks, not every four weeks."

How is it even possible to get two periods in one month?

"The average cycle should occur every 21 to 35 days and last anywhere from two to seven days," explains Lakeisha Richardson, MD, an ob-gyn based in Greenville, Mississippi. So, if you're on the shorter end of that spectrum, that math could easily translate into getting your period twice in one month. And about 40 to 60 percent of women will have some irregular periods throughout their lives, she says.

About 40 to 60 percent of women will have some irregular periods throughout their lives.

Meanwhile about five percent of women can have one period followed by mid-cycle bleeding, says Anna Rhee, MD, an assistant professor of obstetrics, gynecology, and reproductive science at Mount Sinai. "Mid-cycle bleeding occurs during ovulation due to increasing luteinizing hormone (LH surge). It is usually light and lasts two to three days just in the middle of a cycle," she explains.

If you don't just have a cycle that's on the shorter end of the spectrum, your "period" might be bleeding linked to a medical condition or birth control. Even though most of the reasons are totally benign, seeing your doctor can help identify the cause and start treatment early if needed.

Here's what might be going on if you're getting two periods in one month—and what to do to get your cycle back on track.

1. You're on or you forgot to take your birth control.

            Duh, right? "Missing birth control pills or forgetting your Depo-Provera shot will always cause irregular bleeding," says Dr. Richardson. "Anytime you fail to take a birth control method correctly, you will bleed because you have an abrupt withdrawal of hormones." This kind of bleeding, though, is not an emergency."

            You can also experience irregular bleeding if you're just starting to use birth control. "Birth control like the arm implant and IUD can be linked to intermenstrual bleeding or spotting, a.k.a. unscheduled bleeding or random bleeding that isn't a true period. This is especially true the first few months after having either the implant or IUD placed," says Jennifer Lincoln, MD, an ob-gyn based in Portland, Oregon, and the author of Let's Talk About Down There. "In addition, this kind of bleeding can continue with the arm implant no matter how long you've had it, while for many it stops over time with the IUD."

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            What to do about it

            If you resume your birth control by following the instructions after forgetting to take it, the bleeding will subside, Dr. Richardson says. Just make sure to use a backup method of birth control to prevent pregnancy until your next period.

            2. You're pregnant.

            I know: Pregnancy means missed periods. But "believe it or not, some women will bleed irregularly if they are pregnant," says Dr. Dweck. Spotting during pregnancy is very common, especially in the first trimester, and can occur for a number of reasons, including after heavy exercise or sex, or due to polyps (benign lesions that can grow inside the uterus or cervix and bleed spontaneously), says Dr. Richardson.

            Much more rarely, ectopic pregnancies (i.e., when a fertilized egg implants outside of the uterus) can also cause irregular bleeding very early on in pregnancy, says Christine Masterson, MD, the chief of the women and children's service line at Summit Medical Group in New Jersey. Black women are at increased risk of ectopic pregnancy compared to white women, and BIPOC communities are more likely to experience complications due to an ectopic pregnancy. These racial disparities may be due to a slew of complex factors rooted in systemic racism, including poorer access to quality medical care and follow-ups as well as chronic maternal stress.

            What to do about it

            Obviously, a bun in the oven can be ruled out with a simple pregnancy test. Keep in mind that false negatives are relatively common if you haven't yet missed your period. If you experienced earlier-than-expected bleeding after your normal period, take the test again about a week after you'd usually expect to get your period.

            Since ectopic pregnancies also result in a positive pregnancy test and can become an emergency if left untreated, see your doctor for an ultrasound to confirm whether the embryo has implanted in your uterus. If it is an ectopic pregnancy, you'll receive meds and potentially other treatments to prevent life-threatening complications.

            3. You have uterine or cervical polyps or fibroids.

            Uterine issues like polyps or fibroids—benign lesions or tumors that can grow in the uterus—are very common and may be related to hormonal issues. "Uterine polyps can cause bleeding in between periods," says Dr. Dweck, especially if they are touched, like during sex, and "fibroids can cause pain, back pain, abdominal bloating, anemia, pain with intercourse, and spontaneous bleeding because they're not associated with the menstrual cycle," explains Dr. Richardson.

            While fibroids can affect women of any age or race, Black women are about three times more likely to develop them compared to white women, and their symptoms tend to emerge at an earlier age with greater severity. It's unclear why exactly Black women are disproportionately impacted by fibroids, but some studies suggest that greater exposure to racial discrimination or genetics could play a role.

            As the Black Women's Health Imperative notes, heavy, painful periods may seem like a fact of life since they're so common—and many women wait years to seek treatment for fibroids—but you don't have to needlessly suffer.

            What to do about it

            Head to your ob-gyn for an ultrasound, a uterine biopsy, or a hysteroscopy (a scope that looks into the uterus). Hormonal medications such as progestins (sometimes in the form of an IUD) and gonadotropin-releasing hormone agonists may lessen symptoms of polyps and shrink uterine fibroids.

            Sometimes, surgery or other medical procedures might be necessary to remove the growths. "Removal of the growths is usually curative and ensures that there are no other causes of irregular bleeding," says Dr. Richardson.

            4. You have an infection down there.

            Vaginal and cervical infections are incredibly annoying for a number of reasons, not least of all that they can cause bleeding outside of your period. "Inflammation or infection of the cervix with bacteria, such as bacterial vaginosis or trichomoniasis, can cause irregular bleeding," says Dr. Richardson.

            Many STDs often don't cause any other symptoms, although you may experience foul-smelling or gray, white, or green discharge; itching or burning in your genital area; or burning during urination.

            What to do about it

            Check in with your doctor ASAP; these infections can be quickly and effectively treated, usually with antibiotics. "Research has shown that sexually transmitted disease such as trichomoniasis increases your risk of contracting HIV and other STDs," she says.

            Here's how to tell if it's a yeast infection—or something else:

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            5. Your thyroid isn't working properly.

            An underactive or overactive thyroid gland can cause your period to come twice in one month. "The thyroid gland is regulated by hormones produced and regulated in the same area of the brain—the pituitary and hypothalamus—as the hormones that control menstruation and ovulation," explains Dweck. "When one is off, the other might be affected."

            If you have hyperthyroidism (where your thyroid produces too much of the thyroxine hormone), you may also lose weight unexpectedly, feel nervous or anxious, have a rapid heartbeat, or have trouble sleeping. Hypothyroidism (too little thyroxine hormone) can cause weight gain, constipation, fatigue, and increased sensitivity to cold, among other symptoms.

            Your risk of developing a thyroid disease could vary by race, potentially due to a combination of environmental and genetic factors. According to a 2014 study in the Journal of the American Medical Association , Graves disease, an autoimmune disorder often at the root of hyperthyroidism, is more common in Black, Asian, and Pacific Islander women compared to white women. On the other hand, Hashimoto's disease, which often causes hypothyroidism, is more common in white women.

            What to do about it

            A thyroid condition is diagnosed with a blood test and typically treated with medication. Hypothyroidism drugs restore your levels to a normal level, so symptoms should disappear and you will start feeling better soon. Hyperthyroidism medications can clear up symptoms within a few weeks by keeping your thyroid from overproducing hormones. Most of the time this treatment permanently fixes the issue, although sometimes you may need surgery.

            6. You have PCOS.

            Polycystic ovarian syndrome is a hormone imbalance that affects between eight and 20 percent of women, according to the National Institutes of Health. "It's a result of less frequent ovulation or the lack of ovulation, leading to an imbalance of estrogen, progesterone, and testosterone," Dr. Dweck explains. "One of many symptoms includes irregular bleeding."

            While PCOS causes irregular periods, many women actually experience less frequent or skipped periods. Other commonly associated symptoms include acne, difficulty maintaining weight, hair growth in places typical to men (like the upper lip or chin), and fertility issues, she says.

            As WH has previously reported, PCOS doesn't seem to be more prevalent in any one racial or ethnic group, but your symptoms could differ. For example, Latinx people tend to develop more severe PCOS symptoms like acne, hair loss on the scalp, and unwanted hair growth elsewhere. Black individuals with PCOS may be at increased risk of developing heart disease. On top of this, systemic racism and implicit bias create barriers to proper diagnosis and treatment: BIPOC might not be able to access quality health care for an exam, and medical providers may not take their symptoms as seriously as those of white women.

            What to do about it

            If you think there's a chance you have PCOS, schedule an appointment with your doc to be evaluated with a pelvic exam, ultrasound, and blood test. If PCOS is causing irregular bleeding, you'll likely be put on birth control pills or progesterone therapy to regulate your cycles. And since PCOS symptoms are often linked to weight gain, your practitioner may suggest lifestyle changes to help you lose weight.

            7. You have precancerous or cancerous cells.

            When found in either the uterus or cervix, precancerous and cancerous cells can cause irregular bleeding. "Suffice it to say, a tumor growing on the cervix or uterus can bleed erratically," says Dr. Dweck. One study even found that irregular periods are more likely to lead to ovarian cancer, so early detection is key.

            Incidence rates of gynecological cancer vary by race and ethnicity—cervical cancer disproportionately impacts Hispanic women, while Black women and white women are more likely to develop uterine cancer, per the CDC.

            What to do about it

            Uterine and cervical cancers are diagnosed with an ultrasound and uterine biopsy, and a Pap smear and cervix biopsies, respectively, so if you've ruled out other causes, get to an ob-gyn STAT.

            8. You're seriously stressed out.

            High levels of stress can cause either more frequent periods or completely missed ones, says Dr. Masterson, because the hormones that trigger your ovaries to ovulate every month originate in the brain (you know, the same place where stress hormones are released).

            Basically, when you're swamped at work or worrying a lot (especially if it's causing you to get less sleep), those hormones can misfire and affect your cycle in negative ways.

            What to do about it

            If you know you've been mentally stretched to the limit lately, consider doing some yoga or meditation exercises, or talking to someone who can help manage your stress. You'll be surprised how much it can help your mind and body, says Dr. Masterson.

            9. You've been traveling recently.

            If you get back from vacation and find an earlier-than-expected period welcoming you home, you might be able to blame said vacation on your irregular bleeding. Depending on how far from home you went, excessive traveling can disrupt your period.

            "Interfering with your circadian rhythms, like changing time zones or working night shifts, can cause changes in the hormones that trigger your cycle," says Dr. Masterson.

            What to do about it

            As long as the travel was a one-time thing, this should resolve on its own. If you work the night shift regularly, though, irregular periods might be your new normal. Aim to clock at least six hours a night, and make the most of the sleep you do get by blocking out noise and light and avoiding using screens (like your phone) right before you nod off.

            Since you're already feeling the effects of late nights—and shift work can harm your health over time, increasing the risk of anxiety, depression, GI problems, and even heart disease—you may want to talk to your boss about whether it's possible to rework your schedule.

            10. You're in the early stages of menopause.

            Menopause typically occurs at 51.4 years of age, says Dr. Chrisomalis-Valasiadis, but perimenopause, the period directly before menopause, can start at as early as 46 to 48 years old. "You can actually have your period every two weeks, or you can have your period every two or three months. You start getting irregular," she explains.

            It can also lead to periods that are heavier than usual, adds Dr. Masterson. Other symptoms to watch out for include hot flashes, night sweats, vaginal dryness, and sleep problems.

            What to do about it

            There's not much you can do here (you've got to let nature run its course), but there are ways to ease the overall effects of perimenopause, like medications or other therapies, if your OB has confirmed that's what's happening. Hormone replacement therapy, which involves taking a pill to bump up your estrogen levels, can help ease the discomfort and reduce bone loss linked to menopause.

            11. Your weight is fluctuating.

            Rapid weight gain or loss and excessive amounts of exercise can also affect the hormones that stimulate ovulation, changing the typical pattern of your cycle.

            "Usually if you are doing extreme exercise or have gotten underweight, your body turns off the ovulatory process—it thinks it's in a famine situation, and that's not a great time to have a baby," Masterson explains. "But if you've become extremely overweight, you might see irregular bleeding happening more or less frequently than normal."

            What to do about it

            If you think your weight might be to blame for your irregular periods, check in with your doc—it's possible that there are external factors, like a medical condition or new medication, contributing to your weight gain that would be worth looking into.

            12. You have endometriosis

            Endometriosis is a condition where some of your uterine lining becomes trapped outside of your uterus. That means there's more tissue to shed every month, causing more frequent and heavier periods. Your periods may also be quite painful, and you may have other symptoms like nausea, fatigue, pain during sex, and pain with bowel movements.

            Asian women are more likely to be diagnosed with endometriosis, while Black and Latinx women are only about half as likely to be diagnosed with endometriosis when compared to white women, as WH has previously reported. Part of this disparity can be traced back to racial bias—medical professionals may downplay BIPOC's symptoms or attribute them to anxiety rather than endo, and they tend to under-treat Black women's pain.

            What to do about it

            Check in with your doc, who may run a few tests, such as ultrasound, pelvic exam, and possibly an MRI or biopsy. If endometriosis is to blame for your irregular periods, you might get a prescription for birth control or another hormonal therapy that can help reduce the pain and slow the growth of endometrial tissue.

            13. You have a bleeding disorder.

            Bleeding disorders are commonly diagnosed when someone has very heavy periods, says Dr. Lincoln. "It could also lead to intermenstrual bleeding, especially in young teens whose cycles are just starting," she explains. The most common bleeding disorder that can lead to heavy bleeding is Von Willebrand's disease, where the blood doesn't clot properly.

            What to do about it

            If instructed by your doctor, taking birth control continuously can avoid period bleeding altogether. You may also be prescribed medication to stabilize blood clots or to increase your body's levels of Von Willebrand factor, which aids blood clot formation.

            14. You've recently taken emergency contraception.

            If you've taken an emergency contraceptive and found that you bled shortly after, it's because the hormone levels in Plan B, for example, are similar but higher than the ones released in your body when you use birth control, resulting in spotting. Dr. Lincoln describes it as "short-term and not harmful to your body."

            What to do about it

            While this kind of bleeding is totally normal, it's best to wait until your next period to confirm that you're not pregnant or visit a gynecologist for definitive word sooner. To avoid irregular periods, remember that the morning after pill should not be used as birth control. If you're not already using a regular form of birth control, speak to your gynecologist or primary care doctor about your options.

            15. You have adenomyosis.

            On top of irregular periods, adenomyosis can also cause painful or crampy periods. This condition causes the cells that make up the uterine lining to "invade deeper into the uterus, leading to a uterus that is filled with blood (think of a boggy water balloon)," says Dr. Lincoln.

            What to do about it

            Because adenomyosis is hard to treat, a combination of hormonal birth control, NSAIDs, or other kinds of hormonal medications may be prescribed to suppress your period or reduce other period-related symptoms. A more aggressive option would be uterine artery embolization, where the blood vessels that feed the uterus are blocked off. A hysterectomy may also be needed to remove your uterus in the future.