Getting your period once a month is bad enough, but two periods in one month? It's unpleasant, to say the least. It could also be cause for concern in some instances, according to experts. Periods typically last for three to seven days and arrive roughly every 28 days. While the bleeding you experience [1] during that time can vary — some people's periods follow a start-and-stop pattern [2], for example, while others experience bleeding so light [3] that it could pass as spotting — the time that passes between periods should remain relatively consistent.

In other words, getting your period again after 1 week or periods that happen again after 15 days are not considered normal. If you're suddenly getting your period more than once a month, it could be a sign of an underlying condition. Here, doctors explain what causes a woman, or someone assigned female at birth, to menstruate twice in a month.

What Causes Two Periods in One Month?

First, it's important to understand the difference between spotting and a period. Like the name implies, spotting is less blood than you'd see while menstruating and it can be linked to a number of conditions and lifestyle changes, says Sherry Ross [4], MD, a board-certified ob-gyn, including:

• Pregnancy: Spotting before your next period can be an early sign of pregnancy and is typically referred to as implantation bleeding [5], which happens 10-14 days after an egg fertilizes.
• Rough Sex: Intense sex without proper lubrication can lead to vaginal dryness, which can result in bleeding after sex. [6]
• Stress: The stress hormone cortisol can affect how the ovaries function, which may result in your period coming early or late [7], your periods being shorter or lighter, or even spotting between periods.
• Medications: Certain medications can cause unusual bleeding, including hormonal birth control, which is known to cause spotting when you first start taking it [8].

Other times, intermenstrual bleeding or spotting can be linked to more serious concerns and conditions, explains says Kecia Gaither [9], MD, MPH, FACOG, a board-certified ob-gyn and maternal fetal medicine specialist, and director of Perinatal Services at NYC Health + Hospitals/Lincoln in the Bronx, NY, tells POPSUGAR. This includes:

• Vaginal infection: Vaginal infections, including yeast infections [10] and sexually transmitted infections [11] can result in unexpected bleeding.
• Cervical and endometrial polyps: "A cervical or endometrial polyp is a benign growth of either cervical stroma or endometrial tissue," Jennifer Kaby, MD [12], MPH previously told PS. "This overgrowth or protrusion of tissue makes the small vessels inside the polyps less protected. When friction or mechanical contact occurs, they bleed."
• Hormonal imbalance: Certain conditions that involve a hormone imbalance, like PCOS [13] or thyroid disease can cause significant changes to your cycle, making periods irregular.

Is It Normal to Have Two Periods in One Month?

No — you really shouldn't experience heavier bleeding more often than the standard menstrual cycle. Even light spotting between periods can be signs of something more serious, which is why it's best to discuss irregular bleeding with your doctor. Even if you only experience irregular bleeding or spotting once, flagging it to your doctor can help put your mind at ease.

It's especially important to make an appointment if you're experiencing other symptoms alongside the bleeding, Dr. Ross says. These can include heart palpitations, feeling excessively hot or cold, insomnia, unexplained weight loss or gain, hair loss, breast tenderness, fatigue, pelvic pain, foul-smelling discharge, uterine cramping, lack of appetite, excess hair growth, and heavy bleeding with large blood clots ("grape- to apricot-size," according to Dr. Ross. In these instances, a doctor may perform blood tests or and/or a physical exam to see what's going on and recommend the best course of action, she adds. If your symptoms are dismissed or continue after your visit, don't be afraid to bring them up again or get a second opinion. You know your body better than anyone, so make sure you're getting the answers you need.

Hedy Phillips [14] is a POPSUGAR contributor.