4 reasons why your menstrual blood is THAT colour

Menstrual blood can come in a variety of colours. The colour variation in your period blood depends on a number of factors such as where you are in your cycle, your contraception and whether or not an infection is present. But don't worry, BeYou HQ has put together another handy guide to take you through the menstrual rainbow. 


Black or very dark brown/red blood is incredibly common to have during the first couple of days of your period. Darker menstrual blood is a sign that the blood is old and has taken longer to travel from the uterus and down through the vaginal canal. Generally, darker blood will also contain blood clots. Blood clots are very common and are the result of the uterine lining coagulating and sticking together. If your blood clots are larger than a 50p coin, then it may be worth paying a visit to your GP.


Most menstruators will have bright red menstrual blood when on the second or third day of their period. Period blood tends to be this colour on the heaviest days of your cycle because it is new blood which is excreted faster than older blood. Newer blood tends to be more reddish in colour because it is has had less time in the uterus lining itself and has therefore not oxidised which darkens the blood in colour. 


Light red or pink menstrual blood usually occurs during ovulation. Ovulation bleeding is very common and usually occurs mid-cycle. Those of us with a uterus tend to excrete cervical fluid around the time of ovulation, as your body prepares to release an egg. This tends to look like white in colour and is slippery in its consistency. However, a significant proportion of us do also experience spotting. This is when the cervical fluid becomes mixed with some of the uterus lining. Pinkish fluid could also be a sign of other more serious conditions. You know your cycle best and what is normal for you. If you spot a significant and sudden change in your periods then get in touch with your GP.


Greyish/greenish looking menstrual blood could be the sign of an infection. If you are excreting grey period blood then it may be a sign of bacterial vaginosis. Other common symptoms of bacterial vaginosis also include: 

  • itching in and around the vagina

  • foul-smelling vaginal odour that people often describe as "fishy"

  • burning or painful urination

Bacterial Vaginosis is simply an imbalance in the vagina’s ‘ecosystem’ due to unwanted bacteria. BV can be easily dealt with, with a course of antibiotics prescribed by your GP. 

Welcome to the end of the menstrual rainbow! The majority of menstrual blood is perfectly normal, so please don’t panic. Getting to know your cycle is so important, as any changes you do notice in menstrual blood can be treated much sooner. 

Comment below to let us know if you found this blog useful! Share this article on Facebook, Instagram and Twitter so your fave menstruators can also learn the colours of the period rainbow.

Meet the Author

jess simms

Jess is our Content & Community executive who writes about, well ...everything! She loves talking about period positivity and body positivity and, let's face it, loves a good debate. When she isn't talking about all things BeYou, she has probably got her nose in a book, cuddling her Jack Russell Terrier, Buster 🧚‍♀🐶📖

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