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Why is Your Period Blood Black? 8 Reasons for Black Period Blood

For the majority of women, menses start between the ages of 12 and 13, assuming there aren’t any underlying health issues. Menstruation is the monthly discharge of mucosal tissue and blood from the inner uterine lining through the vagina. Its color, texture, and duration offer vital indications of your reproductive well-being.

The colors of menstrual blood flow can range from bright red to orange, brown, or black. While these variations are generally normal, the appearance of black period blood occasionally warrants medical attention. 

Causes of black period blood and discharge

Black period blood is blood that takes extra time to leave the uterus, becoming oxidized somewhere along the way. Consequently, it turns a darkish brown or blackish hue, bearing some resemblance to coffee grounds. 

Though it may look a bit frightening, black period blood and vaginal discharge isn’t always a cause for concern. It commonly crops up at different times throughout the cycle, particularly towards the beginning of your period.

Vaginal discharge has a lot to say about your health.

Vaginal discharge has a lot to say about your health.

Track it regularly with Flo to be on the safe side.

The possible explanations behind black period blood can be just as complex and diverse as the female reproductive system itself. Here are eight potential factors that should be taken into account whenever you observe black period blood:

1. It’s just the beginning (or end) of your period

Flow tends to be slightly slower at the beginning and end of monthly menses. As mentioned, the longer it takes for this blood to leave the body, the more likely it is to oxidize and turn into black period blood. 

2. Something could be stuck inside you

Believe it or not, black period blood sometimes points to the presence of a foreign object in the vagina. Perhaps you accidentally inserted a second tampon, had sex with a tampon on, or simply forgot to remove it after the last menses. 

Other objects that might get lodged in the vagina include condoms, sex toys, and contraceptive devices such as sponges, diaphragms, rings, or cervical caps. Over time, these will irritate the vaginal lining and trigger an infection. Aside from black period blood, be on the lookout for other warning signs like:

  • Foul-smelling vaginal discharge
  • Discomfort or itching in or around the vagina
  • Rash or swelling of the genital area
  • Fever
  • Difficulty urinating
  • Pelvic or abdominal pain

If you notice black period blood and any of the above symptoms, and suspect something is stuck inside you, seek help immediately. In rare cases, it could lead to a life-threatening infection known as toxic shock syndrome. 

3. It’s retained menses 

Retained menses or hematocolpos refers to when menstrual blood cannot leave the vaginal canal and fills the vagina, slowly growing darker over time. (Note that when blood fills the uterus, it’s called hematometra.) 

What is responsible for this vaginal blockage? Congenital diseases of the vaginal septum or hymen are frequently to blame. In rare instances, the problem is attributed to the absence of a cervix (i.e., cervical agenesis). Or, it could be the result of cervical atresia, which is a type of surgical complication. Since it’s most often caused by congenital abnormalities, both hematocolpos and hematometra have primarily been diagnosed during adolescence.

When the blockage is severe, you might experience a complete lack of menses or amenorrhea. Other symptoms associated with hematocolpos include a cramping pain in the lower abdomen, endometriosis, and adhesions. 

4. There’s a possibility of cervical cancer 

In very rare cases, black period blood, especially in conjunction with irregular bleeding after sex or between periods may be a warning sign of cervical cancer.

In its earliest stages, vaginal discharge is usually clear or white, foul-smelling, and watery, eventually turning into dark brown or black period blood. Other telltale signs in the advanced stages of cervical cancer include:

  • Fatigue
  • Longer or heavier periods
  • Pain during intercourse
  • Bleeding during or after sex
  • Weight loss
  • Pelvic pain
  • Difficulty urinating
  • Difficulty passing bowel movements
  • Swelling in the legs

5. Postpartum lochia has developed

Vaginal bleeding, which occurs 4 to 6 weeks after childbirth, is referred to as lochia. It starts out as a heavy flow that’s reddish in color and contains small blood clots, then slows down after a few days. For the next two weeks, discharge grows increasingly darker, going from brown to dark brown to black. 

After a little while, the color gradually lightens, changing to yellow or creamy, before flow stops altogether. Consult your provider if lochia is bright red, contains plum-sized clots, or if you observe foul-smelling discharge in the weeks after delivery. 

6. You’ve had a miscarriage

Black period blood and spotting is also a red flag for miscarriage, which primarily happens before the 12th week of pregnancy. However, experts estimate that only 15 to 20% of pregnancies will end in miscarriage. 

Aside from noticing black period blood, you may not see any other symptoms of miscarriage such as heavy bleeding or pain. Some women even continue to experience the usual signs of pregnancy, a phenomenon known as a missed miscarriage. Detectable only by ultrasound, it occurs when the embryo stops developing but doesn’t get expelled by the body. 

7. It’s the product of implantation bleeding

Dark brown or black period blood can represent early conception or pregnancy. Implantation bleeding sometimes appears 6 to 12  days after a fertilized egg implants itself into the uterine lining. Fortunately, flow lasts for just a couple of days and is usually light, but may become black if it leaves the vagina too slowly. Apart from spotting, other signs of early pregnancy/implantation include swollen and tender breasts, fatigue, etc. 

Though it doesn’t happen to everyone, if you are in fact pregnant and haveimplantation bleeding, be sure to visit your provider. 

8. You may have a sexually transmitted disease (STD)

Black period blood has been associated with sexually transmitted diseases such as chlamydia or gonorrhea. Dark brown or black discharge is occasionally accompanied by other STD symptoms like:

  • Foul-smelling discharge
  • Burning while urinating
  • Pain during intercourse
  • Bleeding during or after sex
  • Pelvic pressure or pain
  • Vaginal itching
  • Spotting between periods

Left untreated, STDs may spread and result in pelvic inflammatory disease (PID), which infects the cervix, uterus, and other reproductive organs. PID complications include chronic pelvic pain and infertility.

Lastly, dark brown or black period blood might also indicate other underlying health issues, such as endometriosis, uterine fibroids, endometrial polyps, or an ectopic pregnancy.

Black period blood treatment options

If black period blood cannot be attributed to any routine cause, it’s crucial to seek assistance. Treatment options vary greatly, depending on the exact cause of black period blood:

  • Is a foreign object actually stuck in your vagina? Have you been struggling with fever, pain, and dark discharge? Then your provider will need to remove the object right away. 
  • Cases of PID and STD infections, on the other hand, are typically addressed with antibiotics. Follow all instructions provided and finish the entire regimen. 
  • Although missed miscarriages may resolve on their own, most patients require immediate medical assistance. Remedies include prescription drugs or a dilation and curettage (D&C) procedure to remove remaining tissues from the uterus. 
  • With retained menses, surgery might be needed to tackle the conditions which initially caused the blockage. 
  • Cervical cancer is treated with a combination of surgery, chemotherapy, and radiation unique to each patient. 

When to see a doctor

Normal menstrual bleeding lasts two to seven days and comes around approximately every 21 to 35 days. However, black period blood outside of this window is fairly irregular and should be discussed with a health care professional. 

If you spot dark discharge during pregnancy or after delivery, or while entering menopause, please seek help; it could point to a serious underlying issue. Black period blood associated with any of the below symptoms also warrants medical attention: 

  • Heavy discharge
  • Foul-smelling discharge
  • Vaginal itching
  • Cramping, pain, or fever


Black period blood can be either a common monthly occurrence or a symptom of a larger problem. If you suspect you have any of the conditions outlined above, make an appointment with your provider. Treatment of black period blood will be based primarily on what caused it in the first place.










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