Why Is My Period Blood Black And Thick

Why Is My Period Blood Black And Thick? Here’s What It Means

Purpose of Periods

Other than being that time when you get painful tummy cramps, periods are a natural process of your body.

Periods, also known as the menstrual cycle, are an important time of the month. This is when the uterus releases blood out of your body through your vagina. 

But why must it happen? Every month, the ovaries will release the female hormones estrogen and progesterone. These hormones cause the lining of the uterus (endometrium) to thicken and build up in preparation for egg fertilization.

This is your body trying to create a cushioned environment for the fertilized egg to nestle on. But if there is no fertilized egg, the blood and tissue in the endometrium break down, shedding away as period blood.

Why Is My Period Blood Black And Thick?

Thick, black period blood is a sign of older period blood that’s stayed in your uterus longer than normal.

The black colour results from your period blood reacting with oxygen, while the thickness means that most of the water in the ‘old’ blood has evaporated.

It’s common to have thicker, darker period blood toward the end of your menstrual cycle.

What Do Other Period Colors Mean?

The colour and texture of your period blood may change depending on how far you are into your period.

However, certain period blood colours may raise red flags about how your body is doing.

Here’s what period blood colours say about your health:

Bright Red to Dark Reddish-Brown

A healthy period may show as a bright red blood colour. Bright red bleeding indicates a steady flow of fresh blood exiting the vagina. For some, the period may darken towards the end of the menstrual cycle, but it shouldn’t be cause for concern.

Unusual spotting between cycles may suggest an infection. And in rare cases, bright red bleeding may indicate cervical cancer—typically along with heavy flows.

Brown or Dark Reddish-Brown

Brown period blood may indicate early-stage pregnancy, resulting in spotting from egg implantation. Older period blood from the uterus will also appear dark red or brown.

Postpartum bleeding will show as dark red or brown blood for those who have just given birth. Also known as lochia, this is your body’s way of removing excess endometrium from the uterus.

Lochia is not a cause for concern; not all women experience it after giving birth.


Grey period blood is a sign of possible infection. A common condition is bacterial vaginosis, when the balance between the good and harmful bacteria in your vagina is thrown off.

Other accompanying symptoms may include vaginal itching, fever, pain, burning urination, and/or unfamiliar foul odour. Check with your nearest healthcare provider! 


Orange period blood is often a big sign of bacterial vaginosis or other infections. Common symptoms to watch out for are vaginal itching, pain when urinating, and fishy-smelling discharge.

To be on the safe side, seek a healthcare provider or gynecologist!


Pink period blood or spotting may be due to an unhealthy diet, anemia, or a sudden, noticeable loss in weight. Period blood may also appear pink when diluted—when cervical fluid mixes with the period blood exiting your womb. 

Lighter flow toward the beginning or end of your cycle can also make your period blood appear pinker. Low estrogen levels, such as from taking hormonal birth control, can also lead to pink period blood.

Read more: Period Syncing: Real or Fake?

Compostable Pads for Periods

No matter the colour of your period, Aruna has compostable menstrual pads for all your period needs. Our pads are free of chemicals and plastics, so using them won’t compromise your health.

You can use our period pads guilt-free! Since they’re 100% compostable, they can easily break down and release nutrients to feed the soil that helps plants grow.

We don’t just care about your period pains. We also care about the planet we live on. 

Is black period blood bad? 

The short answer is it depends. Black period blood typically means your period blood has reacted with oxygen.

It’s older period blood that took longer to exit your uterus. It’ll usually turn up first as dark reddish-brown before eventually turning black.

In some cases, however, black period blood is a sign of blockage in your vagina. Watch out for other symptoms such as fishy odour in your discharge, fever, vaginal itching, and difficulty urinating. If this is the case, seek your nearest healthcare provider!

Why is my period blood dark, thick, and sticky?

Dark, thick, and sticky blood is completely normal on the heaviest flow days of your period. Darker period blood just means it’s spent more time in your uterus and reacted with oxygen. Thick, sticky blood clots are common signs of heavy menstrual flow. 

Final Thoughts on Why Is My Period Blood Black And Thick?

Ultimately, making an appointment with your healthcare provider never hurts if you’re concerned about the colour of your period.

Our periods tell us a great deal about how our bodies are doing. Everything from the colour and odour to the texture and flow sheds insight into our health. 

During your menstrual cycle, your period blood can vary in colour, brightness, and consistency.

On the first few days of your period, your flow tends to be faster and the period blood will be newer and appear brighter red. As you go further into your period, your period blood tends to darken in hue.

When should you actually see a doctor?

When you notice any unfamiliar period blood colour, unusual pains in your cycle, or significantly irregular periods, it’s best to contact your doctor. 

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