Menstruation, commonly known as a period, typically begins around the ages of 12 or 13 for most individuals, provided there are no underlying health conditions. It is a monthly process where tissue and blood are discharged from the uterus lining through the vagina. The characteristics of menstrual blood, including its color, texture, and duration, can be indicative of a person’s reproductive health.
7 min read
Updated February 03, 2023
Reviewed by Andrei Marhol, PhD, Flo lead medical advisor, Lithuania
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The colors of menstrual blood can vary significantly, ranging from a vibrant bright red to orange, brown, or even black. It’s important to understand that black period blood isn’t literally black but appears this way due to its extreme darkness. While these color variations are often within the normal spectrum of menstrual blood, the occurrence of black period blood can sometimes signal an underlying health issue that requires medical evaluation.
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Causes of Black Period Blood and Discharge
Black period blood is essentially older blood that has taken longer to exit the uterus, leading to oxidation. When menstrual blood is exposed to oxygen, it undergoes oxidation, which darkens its color to dark brown or black, often resembling coffee grounds.
Seeing black period blood or vaginal discharge isn’t always a cause for immediate alarm. It is a fairly common occurrence at different points in the menstrual cycle, particularly at the onset or conclusion of a period.
Vaginal discharge, including the color of period blood, can provide valuable insights into your overall health. There are several possible reasons why you might observe black period blood. Here are eight potential causes to consider:
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1. Start or End of Menstruation
Blood flow is generally slower at the beginning and end of your menstrual period. You can use an online period calculator to predict your cycle and anticipate these phases. When blood takes longer to travel from the uterus and out of the body, it has more time to oxidize. This extended oxidation period is a primary reason why period blood may appear black at the start or end of your period. The slower flow allows for more oxygen exposure, leading to the darker color.
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A woman checking a sanitary pad, demonstrating normal period blood.
2. Retained Foreign Object
Black period blood can sometimes be a sign that there might be a foreign object lodged in the vagina. A common example is a tampon that has been forgotten and left in place for too long.
Besides tampons, other objects that can become trapped in the vagina include condoms, sex toys, contraceptive devices like sponges, diaphragms, rings, and cervical caps. When these objects remain in the vagina for an extended period, they can irritate the delicate vaginal lining and potentially lead to an infection. In addition to black period blood, an infection may manifest with other symptoms, such as:
- Vaginal discharge with a foul or unpleasant odor
- Discomfort or itching in and around the vagina
- Rash or swelling in the genital area
- Fever
- Pain or difficulty urinating
- Pelvic or abdominal pain
If you observe black period blood along with any of these symptoms and suspect that something might be trapped in your vagina, it’s crucial to seek medical attention immediately. In rare situations, a retained foreign object can lead to a severe, potentially life-threatening infection known as toxic shock syndrome.
3. Retained Period Blood (Hematocolpos)
Retained menses, also known as hematocolpos, occurs when menstrual blood is unable to properly exit the vaginal canal. Instead, it accumulates and fills the vagina, gradually darkening in color over time. This trapped blood eventually becomes black period blood.
Congenital conditions affecting the vaginal septum or hymen are often the underlying cause of this vaginal blockage. In rarer cases, the absence of a cervix (cervical agenesis) or a surgical complication called cervical atresia can also lead to retained menses. Hematocolpos is typically diagnosed during adolescence because it is frequently caused by congenital abnormalities.
When the blockage is significant, it can result in a complete absence of menstruation (amenorrhea). Other symptoms associated with hematocolpos can include cramping pain in the lower abdomen and adhesions.
4. Potential Sign of Cervical Cancer
In very rare instances, black period blood, particularly when it occurs with irregular bleeding after sexual intercourse or between periods, could be an early warning sign of cervical cancer.
Early-stage cervical cancer often doesn’t present noticeable signs or symptoms. However, as cervical cancer progresses to more advanced stages, symptoms may emerge, including heavy, watery, bloody vaginal discharge with a foul smell, and vaginal bleeding that can eventually turn dark brown or black period blood. Other telltale signs in advanced cervical cancer stages include:
- Persistent fatigue
- Periods that become longer or heavier than usual
- Pain experienced during sexual intercourse
- Bleeding during or after sex
- Unexplained weight loss
- Pelvic pain
- Difficulty with urination
- Difficulty passing bowel movements
- Swelling in the legs
A doctor consulting with a patient about potential gynecological health concerns, emphasizing the importance of medical advice for unusual symptoms.
5. Postpartum Lochia
Lochia is the normal vaginal bleeding that occurs in the postpartum period, typically lasting for six to eight weeks after childbirth. Initially, lochia is characterized by a heavy flow that is reddish in color and may contain small blood clots. After the first few days, the flow gradually slows down. In the initial postpartum days, the abundant blood can undergo oxidation and become so dark that it may appear almost black. This dark discharge can sometimes be mistaken for black period blood.
As time progresses, the color of lochia gradually lightens, transitioning to yellow or creamy before eventually ceasing altogether. It is crucial to consult a healthcare provider if lochia remains bright red, contains large, plum-sized clots, or if there is a foul-smelling discharge in the weeks after delivery, as these could indicate postpartum complications.
6. Miscarriage
Miscarriage, the loss of a pregnancy, can occur within the first 20 weeks of gestation. Dark red spotting, which may sometimes be mistaken for black period blood, can be an indication of an early miscarriage. Medical experts estimate that approximately 10 percent of known pregnancies end in miscarriage.
Besides the appearance of black period blood or dark spotting, there may not be other immediately noticeable symptoms of miscarriage, such as heavy bleeding or significant pain. In some cases, individuals may continue to experience typical pregnancy signs, a condition known as a missed miscarriage. A missed miscarriage is diagnosed through ultrasound and occurs when the embryo ceases to develop but is not expelled from the body.
7. Implantation Bleeding
Implantation bleeding, which can signal early conception or pregnancy, is sometimes confused with dark brown or black period blood. However, it’s important to note that dark blood from implantation bleeding is relatively rare.
Implantation bleeding can occur approximately 10 to 14 days after a fertilized egg implants into the uterine lining. The bleeding is typically light and lasts for only a couple of days, but if the flow is very slow, it might oxidize and appear black. Apart from spotting, other early signs of pregnancy and implantation may include swollen and tender breasts and fatigue.
Implantation bleeding does not occur in all pregnancies. If you experience spotting and suspect you might be pregnant, it is essential to consult with your healthcare provider for confirmation and guidance.
8. Sexually Transmitted Infections (STIs)
Black period blood or unusual dark discharge has been linked to sexually transmitted infections (STIs) such as chlamydia and gonorrhea. In these cases, dark brown or black discharge is often accompanied by other STI symptoms, including:
- Vaginal discharge with a foul or unpleasant odor
- A burning sensation during urination
- Painful sexual intercourse
- Bleeding during or after sexual activity
- Pelvic pressure or pain
- Vaginal itching
- Spotting between periods
If left untreated, STIs can spread and lead to pelvic inflammatory disease (PID), an infection affecting the cervix, uterus, and other reproductive organs. PID can result in serious complications, including chronic pelvic pain and infertility.
Furthermore, dark brown or black period blood may also be indicative of other underlying health issues, such as endometriosis, uterine fibroids, endometrial polyps, or even an ectopic pregnancy.
Black Period Blood Treatment Options
If you have any concerns about black period blood or are unsure of the cause, it is crucial to consult with a healthcare provider for proper diagnosis and treatment. Treatment options will vary depending on the underlying cause of the black period blood:
- Foreign Object: If a foreign object is lodged in the vagina, symptoms may include fever, pain, and dark discharge. Prompt medical attention is necessary to have the object removed as soon as possible.
- STIs and Pelvic Inflammatory Disease (PID): STIs and PID are typically treated with antibiotics. It’s essential to follow the prescribed instructions and complete the entire course of antibiotics.
- Missed Miscarriage: While some missed miscarriages may resolve naturally, most cases require medical intervention. Treatment options can include prescription medications or a dilation and curettage (D&C) procedure to remove any remaining tissue from the uterus.
- Retained Menses (Hematocolpos): Surgery may be necessary to correct the underlying anatomical conditions causing the blockage and retained menses.
- Cervical Cancer: Cervical cancer treatment is complex and often involves a combination of surgery, chemotherapy, and radiation therapy, tailored to each patient’s specific needs and the stage of cancer.
When to See a Health Care Provider
Normal menstrual bleeding typically lasts between two to seven days and occurs approximately every 21 to 35 days. Experiencing black period blood outside of this typical window may be considered irregular and should be discussed with a healthcare provider.
It is particularly important to seek medical advice if dark discharge occurs during pregnancy, after childbirth, or while approaching menopause, as it could indicate a more serious underlying issue. Black period blood accompanied by any of the following symptoms also warrants medical attention:
- Heavy discharge
- Foul-smelling discharge
- Vaginal itching
- Cramping, pain, or fever
Discover more articles: Period Blood Colors: A Complete Overview Spotting vs. period vs. bleeding: Know the difference
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Takeaway
Black period blood is sometimes a normal variation within the menstrual cycle, or, in less frequent cases, a symptom of a more significant health concern. If you suspect you may have any of the conditions mentioned above, it is advisable to schedule an appointment with a healthcare provider. Treatment for black period blood is primarily determined by its underlying cause.
References
“Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign.” ACOG, 2017, www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2015/12/menstruation-in-girls-and-adolescents-using-the-menstrual-cycle-as-a-vital-sign.
“Bleeding During Pregnancy.” ACOG, 2019, www.acog.org/Patients/FAQs/Bleeding-During-Pregnancy.
“Retained Tampon or Other Object.” Healthdirect, Healthdirect Australia, 2019, www.healthdirect.gov.au/retained-object-or-tampon.
Rezai, Shadi, et al. “Hematometra And Hematocolpos, Secondary To Cervical Canal Occlusion, A Case Report And Review Of Literature.” ResearchGate, Obstetrics and Gynecology International, Mar. 2017, www.researchgate.net/publication/310798780_Hematometra_And_Hematocolpos_Secondary_To_Cervical_Canal_Occlusion_A_Case_Report_And_Review_Of_Literature.
Tobah, Yvonne Butler. “Implantation Bleeding: Normal in Early Pregnancy?” Mayo Clinic, Mayo Foundation for Medical Education and Research, 9 May 2019, www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/implantation-bleeding/faq-20058257.
Cleveland Clinic medical professional. “Abnormal Menstruation (Periods): Types, Causes & Treatment.” Cleveland Clinic, 25 Aug. 2018, my.clevelandclinic.org/health/diseases/14633-abnormal-menstruation-periods.
Munro, Malcolm Gordon, et al. “FIGO Classification System (PALM-COEIN) for Causes of Abnormal Uterine Bleeding in Nongravid Women of Reproductive Age.” ResearchGate, International Journal of Gynaecology and Obstetrics: the Official Organ of the International Federation of Gynaecology and Obstetrics, Feb. 2011, www.researchgate.net/publication/49942833_FIGO_classification_system_PALM-COEIN_for_causes_of_abnormal_uterine_bleeding_in_nongravid_women_of_reproductive_age.
Cleveland Clinic medical professional. “Physical Changes after Child Birth.” Cleveland Clinic, 1 Jan. 2018, my.clevelandclinic.org/health/articles/9682-pregnancy-physical-changes-after-delivery.
Mayo Clinic Staff. “Polycystic Ovary Syndrome (PCOS).” Mayo Clinic, Mayo Foundation for Medical Education and Research, 29 Aug. 2017, www.mayoclinic.org/diseases-conditions/pcos/symptoms-causes/syc-20353439.
Shibata M, Nagai K, Doi T, Tawada H, Taniguchi S. Blood color is influenced by inflammation and independently predicts survival in hemodialysis patients: quantitative evaluation of blood color. Artif Organs. 2012;36(11):992-998. doi:10.1111/j.1525-1594.2012.01490.x
History of updates
Current version (03 February 2023)
Reviewed by Andrei Marhol, PhD, Flo lead medical advisor, Lithuania
Published (17 January 2019)
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