Brown period blood has various causes but isn’t usually a reason to be concerned. Period blood that looks brown is typically older, meaning it had more time to oxidize, resulting in a darker hue. Brown blood before or after your period or during a light or slow flow can be perfectly normal.
However, sometimes, brown discharge can indicate pregnancy or a health concern. Medical conditions like uterine fibroids, polycystic ovary syndrome, and certain infections are some reasons you may have brown period blood.
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1. Slow or Light Menstruation
Having a light or slow flow, in which the blood has more time to oxidize as it leaves the uterus and exits the vagin*, is the most common reason for brown period blood. During this time, blood is exposed to oxygen and turns brown.
For people with a very light flow, blood may appear brown throughout their entire period. This is more common if you use a birth control method that can cause lighter periods.
Forms of birth control that can cause light bleeding include:
- Oral hormonal pills
- Intrauterine devices (IUDs)
- Birth control implants
Adolescents experiencing their first menstrual cycles may have light bleeding. As a result, the blood may look a little brown. It’s also normal for there to be little spots of blood.
Old Blood From Last Period
Old period blood is oxidized blood and takes on a brownish hue. It could be leftover from your last period. You may experience occasional light brown spotting after sex, particularly after vigorous sex or sex with insufficient lubrication. This is due to the dislodging of old blood.
2. Beginning or End of Period
Older blood also has more time to oxidize and thus turn brown.
Consider what blood looks like when you get a cut. At first, the blood is bright red, but it turns brown or darker red as it dries. Your menstrual blood has a similar oxidation process, so it may sometimes appear brown.
- Beginning of period: You may notice brown period blood at the beginning of menstruation, on the first or second day. In some cases, this is due to a light flow. In other cases, it may be blood left from your previous period.
- End of period: For most people, blood flow gets lighter and slows down at the end of their period. That is why you may also notice brown period blood on the final day or so of menstruation.
Ovulation-Related Spotting
For most menstruating people, their flow is lightest and slowest at the beginning and end of their period. However, it’s also possible to get brown spotting mid-cycle, during ovulation. Ovulation is when an egg is released from your ovary. Hormonal imbalances can trigger this bleeding, which is known as ovulation bleeding.
3. Early Pregnancy
Brown period blood could be a sign of early pregnancy. Bleeding, including light brown spotting, is relatively common in the first 12 weeks of pregnancy. However, you should report any bleeding during pregnancy to your healthcare provider.
Early pregnancy is one of many potential causes of brown discharge but does not confirm pregnancy. If you suspect you are pregnant, take a pregnancy test and follow up with a healthcare provider.
4. Ectopic Pregnancy or Miscarriage
Bleeding during pregnancy accompanied by pain or cramping, vagin*l discharge, and dizziness can be a sign of miscarriage. Brown discharge that looks like coffee grounds is old blood that has had time to oxidize in the uterus.
Brown discharge during pregnancy could also be a sign of ectopic pregnancy. This is when pregnancy occurs outside of the uterus. It is potentially life-threatening and needs to be evaluated as soon as possible by a healthcare provider.
5. Fibroids
Uterine fibroids are common, benign (noncancerous) growths that occur in or on the uterus. Their size and location can affect menstrual blood in different ways. Sometimes they block blood flow and make your period blood brown.
Talk to a healthcare provider if you have brown blood during your period along with any of these fibroid symptoms:
- Heavy or prolonged menstruation lasting for more than 7 days
- Anemia, which can lead to fatigue
- Pain during intercourse
- Frequent urination
- Constipation and/or bloating
- Pain in your pelvis or lower back
- Increased menstrual cramping
- Stomach swelling
6. Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) is an umbrella term for inflammation affecting the upper female reproductive tract. It is often due to a sexually transmitted infection.
The symptoms of PID may be mild or very general, which can make PID difficult to detect. Abnormal bleeding is one of the symptoms. Spotting or light bleeding can occur. If the blood has time to oxidize before it leaves the body, it may appear brown.
7. Perimenopause
Perimenopause is the stage that occurs before menopause. It usually starts in a person’s late 40s or early 50s. During this time, the body starts to produce less estrogen. As a result, you may have shorter or lighter periods. If blood flow slows down significantly, you may notice brown period blood.
8. Polycystic Ovary Syndrome
Polycystic ovary syndrome (PCOS) is a common disorder affecting the body’s hormones. It happens when females produce higher levels of “male” hormones (androgens), like testosterone, than normal. Menstrual periods can become irregular as a result.
People with PCOS may have missed, irregular, or very light periods. During times of light or little flow, blood may turn brown as it oxidizes before exiting the body.
Other symptoms of PCOS include:
- Cysts on the ovaries
- Excess body hair, including on the chest, stomach, and back
- Weight gain, especially around the belly (abdomen)
- Acne or oily skin
- Male-pattern baldness
- Skin changes (skin tags, dark patches)
9. Lochia (Postpartum Bleeding)
Bleeding after delivery is normal. This postpartum bleeding is called lochia. It lasts for about two to three weeks. The color is reddish-brown in the first few days, changes to brownish or pinkish, and then becomes whitish or pale.
10. Emergency Contraception
Plan B, an emergency contraceptive, can cause spotting or light bleeding as a side effect. Spotting and light bleeding can mean blood has time to oxidize and turn brown.
11. Infection
Sexually transmitted infections (STIs) and infections of the female reproductive system can cause abnormal bleeding.
STIs such as gonorrhea, chlamydia, and cytomegalovirus (CMV) can cause PID. As a symptom, abnormal bleeding may manifest as brown blood.
Trichom*oniasis is an STI commonly known as trich. People with trichom*oniasis may experience light bleeding, especially after sex, in addition to other symptoms like pain, burning, or itching.
Other causes for light bleeding that may lead to brown blood include a yeast infection, bacterial vaginosis, viral vaginitis, and noninfectious vaginitis.
Summary
Brown period blood is older blood that has had more time to oxidize. It can occur as a light or slow flow, frequently happening at the beginning or end of your period. This is normal.
However, brown period blood can also indicate health conditions like menopause, early pregnancy, infections, PCOS, fibroids, and more.
Talk to a healthcare provider if you notice a change in your menstrual discharge or have accompanying pain or other symptoms.
