Period Blood Colors: A Complete Overview

What affects period blood color

For most women, menstruation consists of 2–3 days of heavy blood flow followed by another 2–4 days of lighter flow. The menstrual flow from the vagina is a mixture of blood and tissue from the inner lining of the uterus. Women vary considerably in the volume of blood that is lost each month; it can be as little as 4 tablespoons or as much as 12 tablespoons. On average, a woman loses about 30–50 ml of blood per period — though losing up to 80 ml is still considered normal. 

There are a variety of factors that affect the color of menstrual blood, including hormonal activity, the age of the blood, and infection. It pays to be aware of the different ways that period blood can present and what this may indicate about your health. 

Bright red period blood

At the start of your period, you can expect the blood to be bright red. During this phase of the cycle, the lining of your uterus is being shed at a rapid pace and you’ll likely experience some menstrual cramps. These pains in the abdomen are the result of an increase in the production of prostaglandins, which cause the smooth muscle in the uterus to contract.

Menstrual cramping, or period pain, is a common symptom for many women and is usually nothing to worry about. It can easily be treated with a hot water bottle over your abdomen or over-the-counter painkillers. If you opt for painkillers, choose a non-steroidal anti-inflammatory drug (NSAID) like ibuprofen from your local drug store or supermarket.

In some cases, intensive flow of bright red blood can be an indication of miscarriage, ectopic pregnancy, submucosal fibroid, endometrial or cervical polyp, endometrial or cervical cancer, or an ovarian cyst. If you have any concerns about menstrual symptoms or your general health, seek advice from a trusted healthcare professional — they are in the best position to assess your circumstances and offer the most suitable range of treatment options.

Dark red period blood

In total, your menstrual cycle lasts about four weeks from the first day of bleeding to the start of the next period. Over the course of this cycle, your hormones rise and fall during different phases, resulting in some of the signs and symptoms that you notice each month.

When your period first starts the blood is bright red in appearance, but later in the cycle the color shifts to a dark red. This change in color is completely normal and accompanies rising estrogen levels in your blood. Dark blood is not as fresh — it’s been in your body longer, for instance as the result of a thicker uterine lining or a reduced rate of shedding.

Pink period blood

Shortly before menstruation is due to start, some women notice light red or pink spotting in their underwear. The color of this discharge is explained easily: a small amount of blood mixes with cervical mucus, which results in pink spotting. This spotting can be a sign of low estrogen levels and, in such cases, it’s best to consult a healthcare professional for further investigation.

Abnormal hormonal activity can be responsible for a range of symptoms in later life, including irregular periods and vaginal dryness, so it’s important to alert your doctor or gynecologist if you have any concerns. They will be able to advise you about the available treatment options.

Brown or black period blood 

If you recall what we’ve already mentioned about changes in the appearance of menstrual blood over the course of your period, then brown or black period blood won’t come as much of a surprise. Period blood starts off bright red, but becomes darker as it remains in the body for longer. At the end of the cycle, you may see brown or even black blood on a sanitary towel or tampon. 

How does red blood become brown or black? Old blood gets darker if it stays outside of blood vessels. When blood comes into contact with air, it goes through a process called oxidation. As the hemoglobin and iron in your blood interact with the air, your blood turns brown.

There are several reasons why blood or uterine tissue may remain in your body for a longer time. It may be that the last remnants of old uterine tissue from a previous cycle are finally being discharged. Or it could be that you’re among the many women who shed their uterine lining at a slower rate than the majority of the population. Aside from the rather unpleasant, tarry discharge that results from it, this slower shedding is nothing to be concerned about.

Other possible period blood colors

Even if you’re well educated about the many different colors of period blood, you may still be alarmed to find an orange shade in your underwear or on a sanitary product. Before you start to panic, check the consistency of the fluid between two fingers — it should be slippery if normal, but if you feel a tackiness or if there’s also a bad smell, it could indicate that the blood has mixed with cervical fluids as the result of an infection or STD. In such cases, seek your doctor’s advice as soon as possible.

Gray or off-white period blood or discharge is a reason to visit your doctor. It can be a sign of an infection like bacterial vaginosis. If you’re pregnant, this color can indicate that you may have miscarried.

You should also be aware of clots in your menstrual blood. This is perfectly normal if blood clots are not bigger than a quarter, particularly during the later stages of your period, and is the result of an increase in the activity of platelets in your bloodstream. At the same time, be aware that excessive blood clotting can be a sign of miscarriage, so be ready to visit your local clinic if this becomes a concern.

Although it’s common for women to be concerned about blood clots during their period, there’s usually nothing to worry about. More often than not, these clots are simply the result of heavy menstrual flow — you’re losing blood at too fast a pace for your body’s anticoagulants to be able to cope. If the clots are upsetting or bothersome, your doctor may be able to prescribe a medication that can bring them under control. And considering you’re losing such a large amount of blood, you may also want to be tested for anemia.