Periods

What different colour period blood means?

Bright Red 

Fresh blood, this blood hasn’t been in the uterus very long

Dark Red / Brown

Older blood, the longer blood stays in the uterus the more it oxidises (combines with oxygen), which causes the colour to darken. Hence when some first gets their period it tends to be dark brown as it has been sitting in the uterus longer than someone who has already been menstruating monthly. This is also the reason blood may be darker at the start or end of the period.

This is in relation to periods, someone bleeding during pregnancy / suspected pregnancy will bleed for different reasons (see page on bleeding during pregnancy)

Light Red / Pink

Pink blood is often red blood that has been mixed with discharge causing it to lighten. This may happen with lighter periods or people on birth control.

Orange / Yellow

This is also usually due to blood mixing with discharge however instead of the discharge being clear it is yellow / green. This may be due to an infection, and you should see a doctor to see if you need treatment. However, this isn’t always the case, and some people's discharge naturally varies in colour without infection, nevertheless it’s still important to check with a doctor in case treatment is needed such as antibiotics.

(see page on what is discharge?)

Grey

Also as a result of mixing with discharge, this is a sign of bacteria imbalance in the vagina, potentially leading to bacterial vaginosis therefore a doctor should be consulted. Treating bacterial imbalances can usually be done by medication.

Black

As mentioned above, the longer blood sits in the uterus the more it oxidises and the darker it becomes. Therefore, the darkest it can become is black. This is usually due to some form of blockage preventing period blood from leaving the body through the vagina causing it to oxidate beyond brown, if this is suspected a doctor should be consulted.