Why Do I Have Brown Period Blood?

The sight of brown period blood or brown discharge can be confusing because we often presume periods come in only one colour – red! What’s important to remember though is this: there’s not a one-size-fits-all flow when it comes to periods. Every woman’s body is different and bleeding can change slightly in colour and consistency with each cycle.

So let’s take a look at when and why you might be seeing brown period blood in your knickers, or on your tampon or pad, and why it’s mostly nothing to worry about.

Brown period blood at the start of your period

To make sense of why period blood is brown, we need a little menstrual cycle refresher. Every month, a woman builds up tissue and uterine lining in the uterus in the event that an egg will become fertilised and implant. If an egg isn’t fertilised after it’s released on around day 14 of your cycle, the body begins to break down the lining, which is then expelled – in the form of your period.

If you notice brown blood at the start of your period, it’s likely that it’s a bit of old blood left over from your previous cycle, or that your flow is starting super-slowly and the blood is taking longer to leave your body. Old period blood appears brown because of oxidation, meaning the blood has been exposed to oxygen for a longer time (it’s helpful to think of this as a similar process to how iron rusts). Fresh blood that leaves your body in a faster flow will be red in colour due to it not being exposed to oxygen for long.

Brown period blood at the end of your period

For similar reasons that you might see brown blood at the start of your period, brown blood at the end of your period is also really common, and will happen when your flow gets slower and lighter – simply because the blood is taking longer to leave your body. Blood will also appear brown the longer it sits on a sanitary pad and is exposed to oxygen.

Brown period blood mid-cycle

Any mid-cycle bleeding is called spotting and there are a few reasons why you might see brown blood between periods. Some women will have some brown bleeding as a result of adjusting to contraceptive and it’s also common to experience a tiny amount of brown spotting during ovulation. Very early pregnancy can also cause some spotting – usually when the egg burrows and implants itself into the uterus wall.

Rarely, brown bleeding or brown discharge between periods can indicate something more serious such as an ovarian cyst, sexually transmitted infections, or in some cases, gynaecological cancer, although it’s always best to get unexplained bleeding checked out by a GP.