Why is my period black or dark brown?

December 02, 2021 5 min read

When it comes to periods, it is important to recognise what is your ‘normal’. By this, I mean what your period looks like during your cycle, how long it lasts for, how often it comes etc. By identifying these factors, you can begin to recognise if something is out of the ordinary. Everyone’s period is different and what is normal for you may not be normal for someone else. A popular Googled question is the colour of your period blood throughout your cycle. Why is it sometimes dark brown or black? Should I be worried? We’re here to give you some answers to these questions!

It is common to have darker blood appear in your panties however if you experience something out of the ordinary, you should always consult with your doctor. Majority of dark period blood is a result of your uterus passing through old blood which has oxidized. However, there are many reasons as to why or how you could be passing through old blood.

  1. Most commonly, your period blood can appear black or dark brown typically towards the beginning or end of your period, when your flow is slow. When this occurs, your uterus begins passing through old or left-over blood that has oxidized. It oxidizes when it takes longer to exit your body which is what happens when your period flow is slow. Through the oxidation process, the colour of your menstrual blood changes from a typical red to a dark brown or black like the colour of coffee grounds.
  1. Irregular periods could be the reason for dark period blood. Irregular periods change your menstrual flow which can result in old blood being passed through on your cycle. Just like the first example above, the blood has time to oxidize because of its slow process, therefore can alter the colour. Irregular periods can occur for a number of reasons including stress, fluctuations in hormone levels or extreme changes in body weight. This can cause your period to be lighter or heavier which can alter the length of your cycle.
  1. The introduction of birth control can affect your period cycle for the first few months. Oral contraceptives alter your body’s hormones to stop monthly ovulation and affect the lining of the uterus to prevent pregnancy. The dark blood is a result of dropping hormone levels making your period very light and exposed to more oxygen, therefore changing the colour. Breakthrough spotting can also occur meaning your body cycles old blood in the uterus.
  1. Uterine fibroids are benign growths inside the uterus that can disrupt your menstrual cycle and cause dark period blood. Uterine fibroids cause abnormal vaginal bleeding, and the blood can potentially stay in the uterus for longer than it should, therefore altering the colour. Uterine fibroids can be a reason for spotting or bleeding in between periods, prolonged or painful periods and constant pelvic pain.
  1. During the premenopausal phase, your menstrual flow can be lighter or heavier and longer or shorter than your usual cycle. Your ovulation becomes less regular causing old blood to be passed through your uterus which can look dark brown or black.
  1. Dark red spotting is often mistaken for black blood and can be a sign of early miscarriage. Approximately 10% of pregnancies end in miscarriage which can occur in the first 20 weeks of pregnancy. Other symptoms of miscarriage can include heavy bleeding, abdominal pain and dizziness.
  1. Implantation bleeding (early pregnancy spotting) is a sign of early pregnancy and happens to around ¼ women. It very rarely occurs in the form of dark blood although can’t be ruled out. The cramping pain and bleeding can occur 10 – 14 days after a fertilized egg implants itself into the uterine lining. You can mistake this type of bleeding for your period, however implantation bleeding is light and only lasts up to two days. The blood is usually a light colour however can be dark if it is leaving the vagina slowly. Other signs of early pregnancy include tender breasts and fatigue. *Please note that implantation bleeding doesn’t occur for all pregnancies.
  1. Pelvic Inflammatory Disease (PID) is an infection of your reproductive organs that can cause irregularities in your menstrual cycle. These irregularities can alter the colour of the blood being passed through your uterus. Symptoms include irregular periods, smelly vaginal discharge and pain in the pelvic region. It is important to get tested for PID as soon as possible as the disease can progress and leave you infertile or result in other complications.
  1. Dark blood and abnormal bleeding can be a result of cancerous growth in your reproductive system. This is generally accompanied with vaginal discharge that is dark and has a bad odour. You should see a doctor for a check-up if this is occurring
  1. Postpartum lochia is where a woman can experience vaginal bleeding in the first four to eight weeks after delivering a baby. The bleeding generally starts out heavy and appears in small dark blood clots before it slows down and lightens in colour after a few days. Women who had caesarean sections may only experience heavy bleeding for 24 hours.
  1. Something could be stuck inside your vagina such as a forgotten about tampon. It is advised to remove the object immediately if this occurs
  1. Black or dark period blood can be a result of contracting and STI such as chlamydia or gonorrhoea. Other accompanying symptoms include:
  • Vaginal discharge with an unpleasant odour
  • Burning while urinating
  • Pain during sex
  • Bleeding during or after sex
  • Pelvic pressure or pain
  • Vaginal itching
  • Spotting between periods

Dark brown or black period blood can also indicate other health issues such as retained menstruation, endometriosis, endometrial polyps, ectopic pregnancy and more.

Veeda are here to help you combat all your period needs offering safe, sustainable, and natural period care for that tricky time of the month. Our period care is dermatologically tested, hypoallergenic, free from nasty chemicals and available at an affordable price. Our products are made from GMO-free natural cotton and cleansed with the purity of oxygen instead of chlorine. Veeda products are fragrance-free, contain no dyes, synthetic fibres, phthalates, pesticides or dioxins. Feel good about using Veeda for all your menstrual needs!

Medical Disclaimer: Articles are intended for informational purposes only and should not be used as the basis of patient treatment. Ask a medical professional if you have any health-related questions or concerns

Additional resources

Hills, J. (2021). Dark or black period blood: causes and what to do about it.

Marcin, A. (2019). Black, brown, bright red, and more: what does each period color mean?

Marhol, A. (2021). Why is period blood sometimes black? 8 reasons for black period blood.

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