The color of your period blood reflects how quickly it’s leaving your body. Bright red means fresh, fast-moving blood. Brown or black means older blood that took longer to exit. Most color variations are completely normal within a single cycle, but a few shades, particularly grey, green, or orange, can signal an infection that needs attention.
Why Period Blood Changes Color
The key factor is time. Blood that moves quickly from your uterus through your vagina stays bright red. Blood that lingers oxidizes, meaning it reacts with oxygen inside your body and darkens, the same way a cut on your skin turns brownish as it dries. That’s why you might see bright red blood on day two of your period and dark brown spotting on day five. Both came from the same source. The only difference is how long the blood sat before it made its way out.
Flow speed also plays a role. When cramps contract your uterus more forcefully, blood exits faster and looks brighter. During lighter flow days, blood moves slowly, oxidizes more, and appears darker. This is why most people notice a predictable pattern: lighter and darker shades bookending the heavier, redder days in the middle.
Bright Red Blood
Bright red is the color most people associate with a “normal” period, and it typically shows up during the first few days when flow is heaviest. It means blood passed through your vagina shortly after entering your uterus. You’re also more likely to see bright red blood during strong cramps, since uterine contractions push blood out faster.
Bright red blood on its own is rarely a concern. Outside of your expected period, though, bright red bleeding can occasionally indicate an injury or, in pregnancy, a sign of labor or miscarriage.
Dark Red, Brown, and Black Blood
These three colors exist on the same spectrum. They all represent older blood that moved through your body more slowly and had more time to oxidize. Dark red is partially oxidized. Brown is heavily oxidized. Black is the most oxidized blood of all.
Brown spotting is especially common at the very end of your period, as your uterus passes the last remnants of its lining. By that point the blood has been sitting for a while, so the dark color is expected. Brown or dark red spotting can also appear at the very start of a period, as leftover blood from the previous cycle finally makes its way out.
Black blood follows the same logic but suggests an even longer delay. In rare cases, black discharge can point to a vaginal blockage, such as a forgotten tampon, which traps blood and gives it extra time to darken. If black discharge comes with a foul smell, fever, or difficulty removing a tampon, that’s worth addressing quickly to avoid infection.
Brown spotting between periods can occasionally be an early sign of pregnancy, or less commonly, a sign of conditions like polycystic ovary syndrome (PCOS) or cervical changes.
Pink Blood
Pink period blood is normal cervical mucus mixing with a small amount of blood, diluting the red color. It tends to show up at the beginning or end of your period, when bleeding is lightest and there’s proportionally more mucus in the mix.
If your period blood is consistently pale pink or watery throughout your cycle, it may be related to iron-deficiency anemia. Heavy periods are one of the most common causes of anemia in people who menstruate, and anemia can in turn make period blood appear lighter and thinner. Other signs of anemia include unusual fatigue, pallor, dizziness, and feeling short of breath during everyday activities.
Light pink spotting outside your regular period window can also be an early sign of pregnancy, sometimes called implantation bleeding.
Orange Blood
A slight orange tint can be normal when cervical fluid mixes with blood, creating a rust-colored shade. Light orange or rust-colored spotting around the time you’d expect your period may also be an early pregnancy sign.
However, orange discharge that’s persistent, has an unusual smell, or shows up with itching or burning often signals an infection, particularly sexually transmitted infections like trichomoniasis. If orange discharge is new for you and doesn’t match up with the start or end of your period, it’s worth getting checked.
Grey or Green Discharge
Grey and green are the two colors that almost always indicate something is off. Grey discharge, especially when accompanied by a strong fishy odor, is a hallmark of bacterial vaginosis (BV), the most common vaginal infection. BV happens when the natural balance of bacteria in the vagina shifts, producing thin, grey or white discharge with that distinctive smell.
Green or yellowish-green discharge typically points to trichomoniasis, a sexually transmitted infection caused by a parasite. Both BV and trichomoniasis are treatable, but they don’t resolve on their own. If your period blood or discharge has a grey or green tinge, particularly with odor, itching, or irritation, that combination is a reliable signal to get tested.
Clots and Texture
Passing small clots during your period is normal. When blood pools in your uterus before exiting, it can clump together into jelly-like clots, especially on heavier days or first thing in the morning after lying down overnight. These are typically dark red or maroon.
Size is the detail that matters most. The CDC uses a quarter (about 2.5 centimeters across) as the threshold: clots smaller than a quarter are generally normal, while clots that size or larger can indicate heavy menstrual bleeding. Clinically, losing more than 80 milliliters of blood per cycle qualifies as heavy bleeding, though that’s difficult to measure in practice. More useful signs include soaking through a pad or tampon every hour for several consecutive hours, needing to change protection overnight, or passing large clots regularly.
Heavy menstrual bleeding has many possible causes, from hormonal imbalances to uterine fibroids, and it’s one of the leading drivers of iron-deficiency anemia. If large clots are a regular feature of your cycle, tracking the pattern and discussing it with a provider can help identify what’s behind it.
Implantation Bleeding vs. a Period
One of the most common reasons people search for period blood color is to figure out whether light bleeding might mean pregnancy. Implantation bleeding happens when a fertilized egg attaches to the uterine lining, usually about 10 to 14 days after conception, which can overlap with when you’d expect your period.
A few features help distinguish the two. Implantation bleeding is typically brown, dark brown, or pink, while a period usually starts or becomes bright to dark red. Implantation bleeding is also much lighter: think spotting or a small amount of discharge that only needs a panty liner, not a pad or tampon. It usually lasts one to two days, compared to the typical three to seven days of a full period. If you’re seeing very light, pinkish-brown spotting around the time of your expected period, a pregnancy test is the most reliable next step.
Postpartum Bleeding
After childbirth, vaginal bleeding follows a predictable color sequence over several weeks. The first stage lasts roughly three to four days and looks like a heavy period with dark or bright red blood. Over the next week or so, the discharge shifts to a pinkish-brown color and becomes less bloody. Starting around day 12, it transitions to a yellowish-white discharge that can continue for up to six weeks after delivery.
This progression from red to pink-brown to yellowish-white reflects the uterus gradually healing. If bright red bleeding returns after it had already lightened, or if you’re passing large clots or soaking through pads rapidly, that can indicate the uterus isn’t healing as expected.