Period blood can be pink, bright red, dark red or brown, and all of that is normal. Colour mostly shows how long the blood took to come out: fresh blood is bright, and blood that lingers turns darker. Gynaecologists rarely ask about colour and care more about how much you bleed and when.
Why is it pink one day and almost black the next?
On the heaviest days blood comes out fast and stays bright red. Towards the end the flow slows, blood stays in the womb longer and turns brown, sometimes so dark it looks almost black. Pink shows up at the start and on very light days, when a little blood mixes with discharge.
Are clots normal?
Yes, small clots on the heaviest days are common. When there's a lot of blood, it has time to sit in the womb and clot, like blood on a scratch. That's why a clot often comes out when you get up in the morning or stand after sitting for a while.
Clots up to 2.5 cm, about the size of a large coin, are usually nothing to worry about. They look like dark jelly, sometimes with bits of womb lining, which is what a period sheds anyway.
What if it looks grey or greenish?
Discharge can take on that colour, and it can be a sign of infection. Thin grey discharge with a fishy smell happens with bacterial vaginosis, and green or frothy discharge with trichomoniasis. It's easy to check: a doctor can take a swab.
Common questions
Almost black blood on day one: is that bad?
Dark colour on its own isn't a bad sign. That's how blood looks when it comes out slowly. Watch everything else: pain, smell, how heavy it is and whether it came on time.
Pink and watery: what does it mean?
On the first, last and very light days, it's a little blood mixed with discharge, which is common. If your whole period now looks like this, mention it at a routine appointment. And if you could be pregnant and only pink spotting came instead of a period, take a test.
In short
- Colour rarely matters much: watch the amount and the timing
- The clot benchmark: 2.5 cm, about a large coin
- Note heavy days and clots in the calendar
Source: NHS: Periods
Educational content; it does not replace professional medical advice.