What does the colour of my period blood mean?

Sep 19, 2019

Dr. Ashley Margeson

Dr. Ashley Margeson


Let’s get real around here gals. Periods are a normal event for 50% of the worlds population, and they can tell us a LOT about how healthy we are. If you’re like the majority of women who come into my office though, you probably didn’t realize just how many things can be discovered from what comes out of your body. 

The variations in period blood colours are usually not pathological from my medical perspective, but they can be used to identify certain hormonal imbalances, nutrient deficiencies and even infections. In my practice I use this information as a marker to determine what kind of labs and testing to order when trying to reach a diagnosis, 

So, where does the colour in period blood come from? 

You might be surprised to learn that the colour comes from blood. The longer period blood is exposed to oxygen, the darker the colour will be. The faster your uterine lining sheds, the less blood is exposed to oxygen, therefore the brighter the hue of the blood will be. Shedding of your endometrium (the part that sloughs off when you’re menstruating) is slower at the beginning of your menstruation, and faster during the middle. This is why you can have different colours of your period blood. 

The Rainbow of Periods

You and I both know that there are many shade of “normal” when it comes to periods… and there are also some causes of “not normal” as well. For a full range of shades of… red, continue reading! 


[ONE] Dark Red or Brown Period Blood 


Darker blood indicates normal, rising levels of estrogen as well as a thicker uterine lining. As your full menstrual flow starts, your estrogen starts to rise. If you are experiencing darker blood at the beginning of your menstruation this makes sense medically.

However, you can also experience darker spotting during the middle of your cycle. This sometimes happens when a fertilized egg implants into the endometrium. This is called implantation bleeding and you may want to buy a pregnancy test… especially if you are also experiencing extreme fatigue breast tendeness, nausea and vomiting. 

Brown discharge after birth is also very normal, it is called lochia. 

Dark brown bleeding can also be a hallmark symptoms of something known as Polycystic Ovarian Syndrome (PCOS). PCOS is a syndrome of androgen excess, which means that you generally have more bioavailable estrogen and testosterone than someone who wouldn’t experience this. 

If you are experiencing brown bleeding coupled with irregular periods, cystic acne, weight gain, unusual hair growth and infertility you should be screened for PCOS. 


[TWO] Bright Red Period Blood



If you are experiencing bright red period blood, your period is indicating a normal, healthy flow. Your uterine lining is shedding at a good pace, the oxygenation rate is good, you have few clots and your inflammation is low. 


[THREE] Clotty Period Blood 


Speaking of clots; when your period is at it’s heaviest, you may experience some blood clots. A few here and there, you don’t feel them pass and they don’t impact your collection method is totally normal. 

But – clots larger than a quarter are not normal. The size of a small raisin, no big deal; but feeling them pass, having them fill a cup or overflow a tampon is not normal. When I’m ruling out endometriosis, the first thing I look for is a large amount of clots accompanying my patient’s menstruation. Endometriosis is an inflammatory condition, therefore you tend to see more pain alongside clots and heavy bleeding. 


[FOUR] Pink Period Blood 


Pink period blood depends on what part of your cycle you’re in! If you’re witnessing pink period blood during the middle of your cycle, it’s probably a very healthy indicator that you’re ovulating and has no cause for concern. Don’t fret though! Not all women experience this, so if you’re not getting a light spotting mid-cycle everything is fine and dandy. 

If you are experiencing pink period blood and you’re over 40; it could mean that you’re starting to see lower levels of estrogen, we can be an indicatory of perimenopause. If you’ve started seeing pink period blood just after starting a birth control pill, this is a perfectly normal response that the pill has on your body. 

Other causes of pink period blood can be an indicator of anemia (aka a lack of proper diet that meets your individual needs), an infection (get that one checked out asap!) or mixing with cervical fluid (totally normal!) 

It’s best to schedule a chat with your friendly naturopathic doctor or medical professional if you’re experiencing pink blood during your period as it can be a sign of cervical cancer. You never want to be too careful when it comes to your lady parts! 


[FIVE] Purple Period Blood 


Soooooooo the rainbow keeps on going, and yup – purple is a thing. I’ve literally seen it in my clinical practice. At it’s most basic level, purple period blood is an indicator of excess levels of estrogen, which can be properly managed using a lot of diet and lifestyle factors. 

Step number one in getting your estrogen under control? Upping your dietary fibre. 

Usually purple blood isn’t a huge cause for worry, but if you’re also experiencing large clots, sharp stabbing pains, intense cramps and an extremely heavy flow you should contact your healthcare practitioner so they can evaluate you for the possibility of endometriosis, fibroids or even anemia. 

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