Why is my period blood brown?

If you notice brown period blood, there’s typically nothing to be worried about. “Brown period blood is a relatively common occurrence and is typically not a cause for significant concern,” says Michael Green, MD, OB/GYN and co-founder at Winona. This color change “usually results from the slow release of old blood that has oxidized, giving it a brownish hue,” says Dr. Green.

Most cases of brown blood occur as your period flow slows down, but blood can be brown for other reasons, too. Here, we’ll go into detail about the various reasons period blood can be brown, when brown period blood may be a concern, what the other possible colors of period blood mean, and how to maintain a healthy menstrual cycle.

What causes brown period blood?

While most cases of brown period blood are simply from your period blood flowing slower and becoming oxidized, certain medical conditions or medications may also cause brown period blood. Let’s take a closer look at the various causes of brown period blood and what type of symptoms require a visit to your healthcare provider.

Starting or ending your period

Have you ever wondered, “Why is my period blood brown on the first day?” The most common cause of brown period blood is because bleeding is slower at the start of the period, allowing more time for oxidation in the vaginal canal. “With the addition of oxygen, this blood will change from a bright red to brown or black,” says Ruth O. Arumala, DO, MPH, gynecologist and co-chief medical officer at Zuri Fertility. 

“It’s also possible to have brown spotting or bleeding for most of your period,” says Kelly Culwell, MD, OB-GYN, also known as Dr. Lady Doctor: “If your period is brown for the entire time, that likely just means that the flow is light.” 

Endometriosis

Endometriosis is a condition that causes cells from your uterus to grow in other parts of your body, such as your ovaries, rectum, and bladder. In addition to causing painful periods, endometriosis can cause abnormal bleeding. “This bleeding may look like thick blood, but it can also lead to brownish bleeding or dark blood during your period,” says Shandra Scruggs, RN, registered labor and delivery nurse and doula, and the founder of Simply Birthed. If you have symptoms of endometriosis, such as intense cramps or heavy flow, you should visit your healthcare provider for treatment.

Endometrial polyps

“A lesser-known cause of brown bleeding during your period is endometrial polyps,” says Dr. Green. Endometrial polyps are small benign growths in your uterine lining that can cause irregular bleeding. “The brown color occurs when blood pools in the polyps before being discharged,” Dr. Green explains. “Other symptoms might include heavy or irregular bleeding, pelvic pain, or spotting between periods.” Visit your healthcare provider if you experience any of these symptoms.

Uterine fibroids

Uterine fibroids are another kind of benign (non-cancerous growth) in the uterus that can lead to abnormal bleeding. Uterine fibroids can affect your periods, “leading to brownish blood, especially if they block the flow,” Scruggs says. Uterine fibroids are common and don’t always require treatment. But if you are noticing unusual symptoms, such as abdominal pain, low back pain, discomfort while urinating, or heavy or unusual period flow, you should consult your healthcare provider.

Implantation bleeding

If you’ve conceived during your cycle, you may experience some brown bleeding or spotting around the time you are expecting your period. This may be due to implantation bleeding, which is an early sign of pregnancy that occurs when the fertilized egg implants in the uterus. “This blood is minimal, so it may take a long time to exit the body, resulting in an ability of the blood to be oxidized, thus resulting in the brown color,” Dr. Arumala explains. It’s typically normal to experience light bleeding and mild cramping during early pregnancy. Still, if your bleeding becomes heavy or is accompanied by intense cramping or dizziness, you should consult your healthcare provider immediately. 

Postpartum bleeding

It’s normal to experience menstrual-like bleeding for about three weeks after giving birth, whether vaginally or by C-section. This postpartum bleeding is called “lochia.” Toward the end of the postpartum bleeding period, it’s common to see some brown blood. “The flow tends to slow down as you near the end of postpartum recovery, thus allowing for oxidization,” Dr. Arumala says. Although lochia is normal, reasons to contact your healthcare provider postpartum include:

• Bleeding that has a foul smell, becomes heavy, or is accompanied by large clots or intense cramps
• Signs of infection, such as a fever, weakness, or dizziness

Hormonal fluctuations

Changes in your hormonal makeup can change your period flow and cause brown period blood, according to Scruggs. For example, polycystic ovarian syndrome (PCOS) is a common hormonal disorder that can cause irregular periods. High stress levels can also affect hormone levels, potentially changing period bleeding and causing brown discharge, according to Scruggs, who adds that thyroid imbalances may also impact periods, leading to brownish discharge.

Hormonal Birth Control

Sometimes, birth control pills and other forms of hormonal birth control—such as hormonal IUDs, birth control shots, and patches—can lead to changes in bleeding, including brown period blood. This is typically a symptom of your body adjusting to the medication, but you should contact your healthcare provider if this irregular bleeding lasts more than three menstrual cycles. 

Pelvic inflammatory disease (PID)

Infections in your reproductive system can cause your period blood to change color. According to Scruggs, pelvic inflammatory disease (PID) can cause brown period blood or brown discharge. PID is an infection of the female reproductive organs, often caused by sexually transmitted diseases (STDs) like chlamydia and gonorrhea. PID can be treated effectively, especially when caught early. See your healthcare provider if you have symptoms such as lower abdominal pain, discharge with odor, unusual bleeding, burning while urinating, fever, and spotting or bleeding between periods.

Tracking color changes during a period

If you notice any usual bleeding patterns or menstrual blood colors, it can be helpful to track your menstrual cycle. Typical menstrual cycles last anywhere from 24–38 days, with usually no more than eight days of bleeding.

Keeping track of your cycle by using a calendar or an app on your phone can help you understand whether your periods are regular or irregular. Writing down the type of flow (e.g., heavy, light, or spotting) and the color of your blood each day is also helpful. If you notice anything unusual, you can share your tracking notes with your healthcare provider.

It’s common for period blood to change colors, even from one cycle to another. “Period blood can vary in color, and these variations are often due to different factors,” says Scruggs, who shares a breakdown of some of the colors you might encounter and what they mean:

• Bright red: This is what you’ll usually see at the beginning of your period. It indicates a steady flow of new blood.
• Pink: Light pink blood typically occurs at the start or end of your cycle and is usually a mix of blood and cervical mucus.
• Brown: This is old blood that has taken longer to leave the uterus. It’s typical at the beginning or end of your cycle.
• Black: This can also indicate blood that has taken longer to exit the uterus, but it can also be a result of medications or supplements. Persistent black blood should prompt a call to your healthcare provider.
• Green or gray: These colors may be a sign of infection. If also accompanied by an unpleasant odor, pain, or fever, seek medical attention immediately.
• Orange: Period blood that’s orange can occur from a mix of red blood and cervical fluid.
• Clotty or tissue-like: Small clots are usually normal, especially during times of heavy flow. Consult your healthcare provider if you are experiencing large, frequent clots along with heavy bleeding.

Steps to maintain a healthy menstrual cycle

It typically isn’t necessary to do anything in particular to maintain a healthy menstrual cycle. Additionally, lifestyle changes don’t always solve issues like heavy bleeding or painful periods, which are usually caused by underlying medical conditions. That said, taking care of your overall health and getting regular medical check-ups can keep you healthy overall and help keep your cycles in check.

Dr. Arumala shares the following tips for maintaining a healthy menstrual cycle:

• Eat whole foods, lean meats, and plenty of fruits and vegetables.
• Stay properly hydrated.
• Track your periods and record any irregularities.
• Get adequate rest during your periods.
• Manage your stress.
• Exercise regularly.
• Address any underlying medical issues affecting your period with your healthcare provider. 

Summary: Recognizing abnormal period colors

Brown period blood is usually not a problem. However, it’s important to recognize when brown period blood isn’t normal. “If you notice persistent changes in your menstrual cycle, such as consistently brown or unusual bleeding, severe pain, or other concerning symptoms, you should seek medical guidance from your healthcare provider,” Dr. Green advises.

The bottom line is that although brown period blood can be alarming at times, it’s almost never something to stress over. “In most cases, brown period blood is a normal part of menstruation,” Dr. Green assures.