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What are period clots and why do they happen?

what are blood clots and why do they happen?

Period clots are normal. Lots of us get them each and every time we have a period, but we don’t really talk about it. And yes, clots can look a little scary- but in most cases they’re not usually anything to worry about. So what exactly are period clots and why do they happen? Let’s discuss. 

What does period blood look like?

Knowing what period blood  is supposed to look like can help when it comes to identifying whether or not you’re passing clots during your period. 

Your period blood can change in colour and consistency throughout your period, and that’s absolutely normal. Right at the start of your period, the blood will be bright red. In the middle of your period, it might turn a lighter, more of a  pinkish colour. Then towards the end of your period it will be darker, more of a brown colour as your body sheds the last of the blood.  

If your period is heavy, your flow might be dark in colour throughout the entire time that you’re bleeding, tailing off to a brownish colour at the end. Heavier bleeding will be thicker in consistency too. 

Sometimes, period blood can look almost orange in colour- this happens when it mixes with cervical fluid. It might have a kind of jelly-like appearance too- but be aware that an orange tinge can also be a sign of infection, so look out for other signs such as irritation or soreness down there and/ or a fever. Vaginal discharge can also turn grey or green in colour if an infection is present, so look out for those colours too. 

If you notice anything that is out of the ordinary for you or you’re concerned about your flow, make an appointment to see your doctor to discuss. We recommend a good pair of heavy flow period pants to absorb your flow- clots and all- and to gently support your tummy when you're feeling tender. 

what are period blood clots and why do they happen?

What are period clots?

Period clots are simply lumps of blood and endometrial tissue that the body expels during your period.

You might pass clots if your period is particularly heavy and for some, this can be during every single cycle. Period clots are thick, often stringy lumps, dark in colour and usually no bigger than a 10p coin. The NHS advises to speak to a doctor if you do pass bigger clots, as it could be a sign that something isn’t right. 

What causes period clots?

Period clots form when blood has chance to build up in the uterus before it leaves your body via the vagina. But there are some conditions that can cause clots too:


Endometrisosis is a condition which affects around 1 in 10 women in the UK, but it can be really difficult to get a diagnosis. Most will suffer with symptoms for around seven years on average before they can access treatment. 

Endometrisosis occurs when cells that usually grow in the uterus begin to grow elsewhere in the body. These cells behave in the same way as they would if they were correctly located, so every month they react to the menstrual cycle and bleed. issues occur because the blood then has no way to flow from the body as your period does. As aa result, sufferers experience inflammation, scarring and pain.

People with endometriosis typically experience very heavy periods, and many will pass clots as a result.

Uterine fibroids

Although lots of people don’t experience any symptoms at all, in some cases Uterine Fibroids can cause heavy periods with clots. 

Speak to your GP about potential treatment if you have fibroids and you’re experiencing period blood clots.


Adenomyosis is a condition where the uterus lining buries itself into the muscular wall of the uterus. People who suffer with the condition tend to experience very long, heavy and painful periods- and some will pass clots too. 

If you have adenomyosis, speak to your doctor about ways to manage the condition.

what are period blood clots and why do they happen?

Pelvic inflammatory disease

Pelvic Inflammatory Disease (PID) occurs when an infection travels up from the vagina or cervix to the pelvic area- the uterus, fallopian tubes and ovaries. Those with PID can experience very heavy and painful periods, and again this can include blood clots. 

Its important to see your doctor if you experience the symptoms of PID- see this guidance from the NHS for more information. If left untreated, PID can affect fertility, so make sure you get advice as soon as you can.

Ectopic pregnancy

An ectopic pregnancy occurs when the fertilised egg implants outside of the uterus, typically in a fallopian tube. According to the NHS, around 1 in 90 pregnancies are ectopic, and pose a risk to health if left untreated.  

The most common signs include a missed period, severe abdominal pain down one side and vaginal bleeding. Some may experience blood clots as part of this bleeding. You must seek urgent medical care if you suspect an ectopic pregnancy. 


If you pass large blood clots that appear to have a slightly gritty appearance with more lumps than usual, it could be the sign of a miscarriage- especially if accompanied by abdominal cramps, very dark and sudden bleeding. 

Seek medical care straight away if you think you may be having a miscarriage.


As you transition towards the menopause and your body begins to produce less oestrogen, you may notice lots of changes to your cycle. Some will experience lighter periods as a result, and often many cycles will pass without a period at all. Other cycles might bring heavy and painful periods, and lots of people can experience blood clots as a result. 

what are period blood clots and why do they happen?

This is all quite normal, but erratic periods can be annoying and painful too. If you find that heavy bleeding is interfering with your daily tasks, speak to your doctor to see if there are any remedies or treatments you can try to ease the symptoms. 

Is it normal to have period clots?

For loss of us, period blood clots are totally normal- just part and parcel of our menstrual cycle. But not many of us really talk about whether or not we get period clots, or what they look like- and this only leaves more of us in the dark, ashamed and embarrassed. We end up feeling like we're the only ones having this experience... when really, we're all going through the same thing!

Here at WUKA, we believe that period clots are just another conversation that needs to be normalised- and that's why we were so thrilled to launch our TV ad recently- featuring RED period blood, with CLOTS. Gasp! The response we've had to the ad has been overwhelming. So many of you have told us that seeing period blood on TV is empowering, and having clots right there on the screen helps to make you feel less alone. It does happen, it can be a normal part of your cycle, and it's nothing to be ashamed of.

We spoke to WUKA Period Health Expert and Senior Consultant ObGyn, Dr Nitu Bajekal, who told us,

“Doctors agree that a woman’s perception of her period is often more important than a medical diagnosis.

The reality is that many women have heavy periods, including blood clots, which can affect quality of life and daily activities. They are even more common post-partum, where you can pass clots of various sizes."

If you track your period, you’ll know what’s normal for you, and you’ll be able to spot changes quickly. If you are concerned though, its always a good idea to speak to your doctor just in case.

what are period clots and why do they happen?

When to see the doctor 

If your period is suddenly very heavy and painful, there could be any number of reasons why. And if you notice blood clots more frequently, or larger in size there could be something going on that needs investigating.  

Your period is unique to you, so try not to compare it to anyone else. Look for signs that something has changed from your normal. As a general rule, speak to your doctor if you notice: 

  • Your period is lasting longer than normal, more than 7 days
  • Your period is much heavier than normal
  • You’re passing clots bigger than a 10p coin
  • You need to change period protection more often than usual, or even double up
  • You’re bleeding during and/ or after sex
  • You’re passing clots that are greyish in colour


Related posts:

Your Complete Guide to Period Blood Clots

The Complete Guide to Period Blood Colour

How Much Blood do You Lose on Your Period?

Why is My Period So Heavy?

Heavy Periods and Anaemia


What does blood clots in my period mean?

For most, blood clots are a normal part of period blood flow. If you track your cycle and you know what’s normal for you, it’s easier to spot the signs when something isn’t right. Sometimes clots can be a sign of a condition or that something else is going on, so keep a track of your usual symptoms too. 

If you notice much heavier bleeding with clots, or clots that are larger than a 10p coin, speak to your doctor to find out what could be going on. 

What do period blood clots look like?

Period blood clots are usually thick, stringy lumps of blood, dark red in colour. The heavier your period, the darker they can be. 

When should I be concerned about period blood clots?

If you notice other symptoms such as sudden, heavy bleeding, fever or intense abdominal pain you should call a doctor straight away. It’s also a good idea to seek advice if you pass clots that are bigger than a 10p piece.