Understanding Black Period Blood: 10 Common Causes Explained

Have you ever looked down at your period product and wondered, "Why is my period blood black?" Don't worry, you're not alone. While the usual vibrant red flow is typical, sometimes your periods may become darker, almost black, which may raise questions. However, there's no need to panic over this common but often misunderstood menstrual occurrence.

When blood stays in the uterus for a bit longer than usual, it interacts with oxygen, leading to a change in color. This oxidized blood is perfectly normal and often appears towards the end of your period.

However, if you experience this color consistently accompanied by other symptoms like heavy bleeding, unusual cramps, or an unpleasant odor, there may be other underlying reasons.

Let's take a closer look at black period blood and its ten common causes.

What Does Black Menstrual Blood Mean?

Period blood can vary in color throughout your menstrual cycle, and black blood usually appears at the start or end of your period when blood flow is lighter. This happens due to a natural process called oxidation, where oxygen combines with the hemoglobin and iron in your blood, causing it to darken. This process is similar to how a cut apple turns brown over time.

Black or brownish-black blood is usually nothing to worry about, especially if it occurs in a small amount. However, if you experience heavy black bleeding or if it lasts longer than your typical cycle, it's best to consult a healthcare provider. This could indicate an underlying medical condition, such as hormonal changes or uterine fibroids.

Why Does Black Blood Come in Periods?

Here are some of the reasons for black blood during periods:

1. Start or End of the Period:

During your period, the flow changes speed. It can be lighter and slower at the start and end, and the blood may appear darker brown or black rather than bright red. This is because the blood has spent more time in your uterus before exiting your body. The longer it stays, the darker it may become.

Black spotting before your period can also be leftover blood from your previous cycle. This doesn't necessarily indicate anything is wrong. It's simply your body's way of clearing out leftover menstrual blood.

2. Something’s lodged inside the Vagina:

In some cases, a dark discharge instead of period blood may indicate the presence of a foreign object in the vaginal area. This can include tampons, condoms, sex toys, and contraceptive devices like sponges, diaphragms, rings, and cervical caps. With time, these foreign objects may irritate the vaginal lining and cause an infection.

In addition to black period blood, you might experience other infection-related symptoms, such as:

• Vaginal discharge with an unpleasant smell
• Itching or discomfort in the vagina or surrounding area
• Skin rash or edema in the vaginal region
• Having trouble urinating
• Pelvic or abdominal pain
• Fever

If you experience black period blood along with the other concerning symptoms or if you feel discomfort or something inside your vagina, it's essential to talk to your healthcare provider as soon as possible. While rare, this situation could turn into a life-threatening infection known as toxic shock syndrome (TSS) if left untreated.

3. Sexually Transmitted Infection (STI)

The presence of black period blood can be a sign of STIs like chlamydia and gonorrhea. Other symptoms that might occur with dark brown or black discharge include:

• Vaginal discharge with a foul odor
• Burning sensation during urination
• Pelvic pain or pressure
• Vaginal itchiness
• Pain during sexual intercourse
• Bleeding during or after sexual intercourse
• Spotting between periods

STIs are serious infections that require proper medical attention, and if you fail to address them, they can spread. One major complication is pelvic inflammatory disease (PID), which occurs when an untreated STI spreads from the vagina to the cervix, uterus, and other reproductive organs.

While PID shares similar symptoms with STIs, you may experience additional warning signs like fever, chills, or painful or heavy periods. If left untreated, it can cause severe complications, such as chronic pelvic pain, ectopic pregnancy, and infertility.

4. Menstrual Retention:

Menstrual retention, also known as hematocolpos, occurs when menstrual blood can't flow out of the vagina and accumulates inside. This accumulated blood can darken over time, causing discomfort and potential complications. Hematocolpos can happen due to various reasons, including:

• Congenital abnormalities, such as an imperforate hymen or vaginal septum, can block the flow of menstrual blood.
• Rare medical conditions like cervical agenesis (absence of the cervix) or cervical atresia (cervical blockage due to surgery) can also cause the condition.

Hematocolpos is typically diagnosed during adolescence and is often associated with symptoms like:

• Cramping pain in the lower abdomen
• Development of adhesions (scar tissue) inside the vagina
• Endometriosis
• In severe cases, complete absence of menstrual periods (amenorrhea)

5. Endometriosis or Adenomyosis:

Endometriosis and adenomyosis, characterized by the abnormal growth of endometrial tissue, are two conditions that affect the uterus and menstrual health. They may be associated with:

• Persistent pelvic pain
• Dark, coffee ground-like discharge that can occur before, during, or after your period.
• Spotting between periods
• Prolonged bleeding, lasting longer than seven days.

If you experience any of these signs or symptoms, talk to your healthcare provider. They can perform tests to diagnose endometriosis or adenomyosis and help manage the conditions.

6. Implantation Bleeding:

Implantation bleeding happens when the fertilized egg implants itself in the uterine lining, typically 10-14 days after conception. During this process, a light flow of blood may occur, but if it leaves the vagina later, it can appear black.

If you are pregnant, your vagina may discharge dark brown to brownish-black blood during or after implantation bleeding. However, if your discharge is heavy or accompanied by other symptoms like cramps, abdominal pain, or fever, consult your healthcare provider to rule out any pregnancy problems.

7. Missed Miscarriage:

While black spotting and bleeding can occur during a healthy pregnancy, they can also be a sign of a missed miscarriage. This type of miscarriage occurs when the embryo stops developing but remains in the womb without getting expelled.

Missed miscarriage usually does not cause any noticeable symptoms. Some women only discover it during a routine ultrasound, while others may experience changes like a loss of pregnancy symptoms, mild cramping, or dizziness.

8. Postpartum Lochia:

After childbirth, your body sheds the uterine lining and blood that nourishes your baby during pregnancy. This shedding is called lochia, and it's a completely normal part of the postpartum recovery process.

Lochia typically lasts six to eight weeks but can vary from person to person. In the first few days, the discharge is usually heavy and oxidized, resulting in a noticeable dark color or black.

As your oxidized blood gets discharged, the lochia gradually changes. It becomes lighter in color, turning pinkish or brownish, and then eventually yellow or creamy. The flow also becomes lighter and then eventually stops. During these 45 days, your uterus expels the uterine lining and blood.

However, it's important to remember everyone heals in their own time. Some women may have lochia for a little longer, and that's perfectly normal.

9. Risks of Cervical Cancer

If you experience black blood with irregular bleeding, particularly after sexual activity or during menstruation, it could be an early indication of cervical cancer. Cervical cancer might not show any symptoms in the initial stages, but as the disease progresses, symptoms may include:

• Vaginal discharge that is bloody, watery, and heavy
• Vaginal discharge that frequently turns into dark brown or black menstrual blood, along with an unpleasant odor
• Fatigue
• Pain during intercourse
• Weight loss
• Bleeding during or after sexual activity
• Prolonged or heavier menstrual cycles
• Having trouble passing the stool or urinating
• Pain in the Pelvis
• Swollen legs

READ: What are the Causes of Common Period Problems?

10. Emotional and Hormonal Shifts and Menopause

Sometimes, prolonged stress and depression can be the reason for black blood during periods. These emotional changes can alter the uterus's structure, thinning its walls and slowing its lining renewal. This delays cell shedding, leading to faster blood oxidation and dark brown or black periods.

Hormonal fluctuations, often linked to thyroid issues and menopause, can also darken menstrual blood.

Furthermore, changing contraceptive pills can delay menstruation, which can oxidize blood and eventually cause it to become darker in color.

It's important to note that changes in menstrual blood color are common and can be influenced by various factors, including hormonal fluctuations, lifestyle, and overall health.

If your symptoms of black blood in periods are only the color, your uterus is more likely shedding old, oxidized blood. This is a normal part of the menstrual cycle and doesn’t require medical treatment. However, if your flow is heavy and accompanied by other symptoms like foul odor, pelvic and abdominal pain, fever, and difficulty urinating, you should consult a healthcare provider. They can diagnose the underlying condition and address any underlying issues.