Ever noticed how your flow changes colours throughout your period? Paying attention to the colour of your period blood can reveal a lot about your overall health and where you are in your menstrual cycle.
Getting to know what’s normal (and what’s not) for your cycle is essential. It means you can identify any changes – like colours you don’t recognise, the duration of your period or unexplained spotting – and seek medical advice if necessary.
Why does period blood change in colour?
It’s completely normal for your menstrual blood to change colour during your period or even from month to month. The amount of blood you lose varies (like most aspects of your monthly cycle), but it’s usually about 2-3 tablespoons throughout your whole period.
‘The colour of your menstrual blood can vary from bright red to dark brown or even black. The colour changes depending on how long the blood takes to leave your body,’ says Dr Rosén.
What do different period colours mean?
1. Bright red
Your blood will usually be bright red on the heaviest days of your period when you have a steady flow of fresh blood. It’s often brighter in colour because it passes out of your body at a faster rate – meaning it has little time to oxidise and go darker.
‘Some people experience bright-red blood throughout their period, but in most cases, the blood will go from a bright red to a darker colour,’ says Dr Rosén.
Blood clots usually occur during the heaviest days of your menstrual flow and are bright or dark red. ‘Blood clots are due to heavy bleeding, where the blood flow is faster and heavier than the body can process, leading to the formation of clots,’ Dr Rosén explains.
‘Menstrual clots are normal – but they can also be a sign that you have heavy periods (menorrhagia).’
You should see a doctor if:
- Your periods are always heavy
- You feel dizzy, tired or short of breath during your period
- You have stomach pains accompanied by heavy bleeding
- Your period lasts more than 7 days
- You need to change your tampon or pad every 1 or 2 hours
- Your blood clots are larger than 2.5cm (about the size of a 10p coin)
2. Dark red
Dark red blood is very common, especially first thing in the morning. This is because after you’ve been lying down for a while, the blood has oxidised inside your uterus before coming out.
Other possible reasons for dark red period blood include:
Nearing the end of your cycle
You may also notice dark red blood at the end of your period (or at the very beginning) when the blood is moving at a slower pace and has more time to oxidise.
After childbirth, your vaginal discharge (also called lochia) will be a dark red colour. ‘Lochia behaves just like menstrual bleeding – immediately after birth, when the bleeding is at its heaviest, it’s usually bright red and then becomes darker as the flow decreases,’ Dr Rosén says.
If you’re breastfeeding, the bleeding may be redder and heavier due to hormones causing your uterus to contract.
3. Dark brown or black
Dark brown or black blood is just older blood. Like with dark red blood, you may see brown or black blood at the very beginning or end of your cycle when blood is taking longer to leave your body.
Brown discharge or spotting during pregnancy can indicate a miscarriage or an ectopic pregnancy, which is when the fertilised egg implants itself outside the uterus, usually in one of the fallopian tubes. If you’re bleeding heavily and you’re in a lot of pain, it’s important to speak to a midwife or doctor immediately for further investigation.
4. Light pink
Pink blood is likely due to your cervical fluid mixing with your period blood and lightening the colour – you may notice this on days when your flow is light, like at the end of your period.
Other possible reasons for pink blood include:
Anaemia, a condition caused by low iron levels, can also cause pink period blood. ‘Iron is what gives the blood its red colour, and blood may become lighter if iron is low,’ explains Dr Rosén.
‘Light blood loss either during or in between periods is called spotting. While this can be any colour, it can sometimes be light-pink due to the lighter nature of the bleeding’ explains Dr Rosén.
Several factors can cause spotting, including:
- A tear to the vaginal wall during sex
- Sexually transmitted infections, like chlamydia
- Hormonal contraceptives
- Polycystic ovary syndrome (PCOS)
- Fibroids or polyps (non-cancerous growths in the womb)
- Cancers of the cervix, uterus, vulva or vagina
If you experience any spotting between periods, speak to a doctor.
Pink vaginal discharge could also signal low oestrogen levels – and it could be a sign of perimenopause. ‘Low oestrogen levels may lead to pink discharge at different points of your cycle, and not necessarily when you'd expect a period,’ explains Dr Rosén.
‘Oestrogen helps to stabilise the uterine lining. If there’s not enough oestrogen, the lining may break down and shed irregularly, leading to spotting.’
Orange menstrual fluid may be a result of your menstrual blood mixing with cervical fluid.
‘Orange period blood or discharge may also be a sign of an infection, like bacterial vaginosis. Or a sexually transmitted infection, such as trichomoniasis, which is caused by a parasite,’ says Dr Rosén.
‘If you have orange blood, check for other symptoms of an infection, like vaginal itching, an unusual smell or discomfort.’
Grey period blood is usually a sign of an infection, like bacterial vaginosis. ‘It may be harder to identify this blood colour, so I would recommend you look out for other signs of infection, such as a foul-smelling vaginal odour, a burning sensation when you pee and itching in and around the vagina.’
Bacterial vaginosis is usually treated with antibiotics, so it’s important you speak to a doctor.
If you have grey discharge accompanied by blood clots or tissue, there’s a possibility that you’re having a miscarriage. You may experience other symptoms of miscarriage, including cramping and pain in your lower tummy.
When should I see a doctor about my period blood colour?
If you’re worried about any unusual discharge, it’s always good to see a doctor. As well as the colour of your period blood, watch out for changes in the length, texture, heaviness and consistency of your flow.
You should make an appointment with a doctor if:
- You experience new or unusual discharge
- You have irregular periods that change in length and heaviness from one month to the next
- You experience bleeding after menopause
- You miss 3 or more periods
- You experience thick grey vaginal discharge
- You have itching in or around the vagina
- You have a fever with an unusual discharge
This article has been medically approved by Dr Elisabeth Rosén, a Livi doctor who specialises in gynaecology and obstetrics.