Period blood ranges from pink to bright red to dark brown or even black, and each color reflects how quickly blood is leaving your body and how much oxygen exposure it’s had along the way. Most color variations are completely normal and follow a predictable pattern tied to your flow speed. A few colors, particularly orange and gray, can signal an infection worth checking out.
Why Period Blood Changes Color
The color of your period blood comes down to one basic chemical process: oxidation. Hemoglobin, the molecule in blood that carries oxygen, contains iron. When that iron is exposed to oxygen over time, it shifts from a reduced state to an oxidized state. This is the same type of reaction that turns a cut apple brown or makes metal rust. Fresh blood with reduced iron looks bright red. As it sits and oxidizes, it darkens to deep red, then brown, then eventually black.
At high levels of oxidation, blood takes on a characteristic chocolate-brown appearance. So the color you see on your pad or in the toilet is essentially a timer, telling you how long that blood spent inside your uterus or vaginal canal before making its way out.
Bright Red Blood
Bright red is the color most people associate with a “normal” period, and it typically shows up during the heaviest days of your flow. Your uterus actively contracts during menstruation, tightening and releasing to push blood out quickly (which also explains the cramps). Because this blood moves fast, it doesn’t have time to oxidize. It’s fresh, and its color reflects that. If you see bright red blood consistently through the middle of your period, that’s a sign of steady, healthy flow.
Pink Blood
Pink period blood appears when a small amount of blood mixes with clear cervical fluid on its way out, diluting the red color. This is most common right at the beginning of your period, when bleeding is just starting, or at the very end as it tapers off. It can also show up as light spotting between periods.
If you notice pink spotting at unexpected times in your cycle, it may be related to low estrogen levels. Estrogen helps stabilize the uterine lining, and without enough of it, the lining can break down and shed irregularly, producing spotting in various shades of pink. This is particularly common during perimenopause, when estrogen levels rise and fall unpredictably.
Dark Red, Brown, and Black Blood
These three colors represent a spectrum of the same process: blood that has been sitting in the uterus longer and has progressively oxidized. Dark red blood is partially oxidized. Brown blood has oxidized further. Black blood has been there the longest.
You’ll most often see brown or black blood at the very beginning of your period, when the uterus is shedding leftover material from the previous cycle, and at the tail end, when flow has slowed to a trickle. During these low-flow phases, blood simply takes longer to travel out of your body, giving it more time to darken. Seeing black blood can look alarming, but it follows the exact same oxidation pathway as brown blood, just taken a step further. It is not a sign of a problem on its own.
Orange and Gray Blood
Orange and gray are the two colors worth paying closer attention to. Orange discharge can sometimes happen when period blood mixes with cervical fluid near the end of your cycle, and that alone isn’t necessarily concerning. But orange can also indicate an infection like bacterial vaginosis (BV) or trichomoniasis, a common sexually transmitted infection.
Gray discharge is more consistently linked to infection, particularly BV, and should not be dismissed as a normal color variation.
With either color, watch for accompanying symptoms: a strong or unusual odor, pelvic pain, genital itching or soreness, or bleeding between periods or after sex. Any of these alongside a color change points toward infection rather than normal variation.
Blood Clots During Your Period
Small clots during heavier flow days are normal. Your body releases anticoagulants to keep menstrual blood liquid, but when flow is heavy, blood sometimes exits faster than those anticoagulants can work, resulting in clots. They often appear dark red or deep maroon because the pooled blood has had time to partially oxidize.
The threshold to watch for is clot size. The CDC considers blood clots the size of a quarter or larger a sign of heavy menstrual bleeding, which may need evaluation. If you’re also soaking through a pad or tampon every hour for more than two hours straight, especially with dizziness, lightheadedness, or shortness of breath, that warrants emergency care.
Color Changes After Pregnancy
After giving birth, whether vaginally or by C-section, you won’t get a regular period right away. Instead, for two to three weeks, your body sheds lochia: a mix of blood and uterine tissue left over from pregnancy. It starts heavy and dark red, then gradually lightens to brownish-pink, and finally to an off-white before stopping. This color progression mirrors what happens during a normal period but stretched over a longer timeline. It follows the same oxidation logic: the heaviest, freshest bleeding comes first, and the older, lighter discharge trails behind.
Once your regular cycle returns postpartum, you may notice that your periods look or feel different than they did before pregnancy. Color shifts during this adjustment phase are common and typically settle within a few cycles.
What the Pattern Tells You
A typical period follows a rough color arc: pink or brown spotting as things start, bright red during peak flow, then darkening back to brown or black as flow tapers off. This pattern can vary from cycle to cycle and still be perfectly normal. The key information isn’t any single color on a single day. It’s whether your overall pattern changes significantly, whether new colors like orange or gray appear alongside symptoms like odor or pain, and whether your flow volume shifts dramatically in either direction. Your period blood color is a useful signal, but it’s most informative when you read it alongside everything else your body is telling you.