Period blood comes in a range of colors, from bright red to dark brown or even black, and nearly all of them are normal. The color depends almost entirely on how long the blood has been sitting in your uterus before it exits your body. Blood that moves out quickly is bright red; blood that lingers oxidizes and turns darker. Over the course of a single period, you’ll likely see several different shades, and that’s exactly what’s expected.
Why Period Blood Changes Color
The shift from red to brown to near-black is a straightforward chemical process. When blood leaves your bloodstream and sits in the uterus or vaginal canal, hemoglobin (the protein that makes blood red) reacts with oxygen. This converts the iron in hemoglobin from one chemical state to another, and the visible result is a darkening from red to brown. The longer blood is exposed to oxygen, the darker it gets. This is the same reason a cut on your skin forms a dark scab.
This means the color you see is really telling you about speed and timing, not about your health. Fast-flowing blood looks red. Slow-moving blood looks brown or black. Both are the same blood.
The Typical Color Progression Day by Day
Most periods follow a predictable color pattern, though the exact timing varies from person to person. In the first day or two, flow is often light as things get started, and you may see brown or dark red spotting. This is older blood and uterine lining that was already sitting near the cervix.
Days two through four are typically the heaviest flow days. Blood moves through the uterus quickly, so it tends to be bright or medium red. This is fresh blood that hasn’t had time to oxidize. As your period winds down over the last couple of days, flow slows again and the remaining blood spends more time in the uterus. By the final day, what comes out is often dark brown or nearly black because it’s highly oxidized.
Not every period follows this script exactly. Some start bright red from the first hour. Others are brown throughout. Both are fine as long as the overall pattern is consistent for you.
What Each Color Means
Bright Red
This is fresh blood flowing steadily. It’s most common during the heaviest days of your period and simply means blood is leaving the uterus quickly. Bright red blood can also appear during the start of a period that comes on suddenly.
Dark Red
A deeper red usually shows up when flow is moderate. The blood has spent a little more time in the uterus than the bright red stuff but hasn’t sat long enough to turn brown. You’ll often see this shade when you first wake up in the morning, since blood pools overnight while you’re lying down.
Brown or Dark Brown
Brown blood is simply old blood. It commonly appears at the very beginning or end of a period when flow is lightest. You may also notice brown spotting between periods for several reasons: leftover blood clearing out a few days after your period ends, ovulation (which can cause light pinkish-brown spotting mid-cycle), or a reaction to a pelvic exam or vigorous sex. For people in their 40s or 50s, brown spotting between periods can be an early sign of perimenopause. Hormonal conditions like polycystic ovary syndrome (PCOS) can also cause irregular, light brown bleeding.
Black
Black blood looks alarming but is almost always just very old blood that spent extra time in the uterus. It shows up most often during the lowest-flow days at the start or end of a period. In rare cases, black discharge with a foul smell can signal a forgotten tampon or other object in the vagina, which needs to be removed promptly.
Pink
Pink period blood is typically menstrual blood mixed with cervical fluid, diluting the red color. It’s common at the very start or tail end of your period. Pink spotting can also occur with implantation bleeding in early pregnancy. Implantation bleeding is very light, more like typical vaginal discharge than a real flow, and it doesn’t soak through pads or contain clots. If your bleeding is bright or dark red, heavy, or includes clots, it’s almost certainly a regular period rather than implantation.
Orange
Orange discharge is less common and worth paying attention to. It can happen when menstrual blood mixes with cervical mucus, but it can also indicate an infection like bacterial vaginosis or trichomoniasis. About 70% of abnormal vaginal discharge cases trace back to one of three infections: bacterial vaginosis (the most common, accounting for roughly half), trichomoniasis, or yeast infections. If orange discharge comes with itching, a strong or unusual odor, or burning, get it checked.
Gray
Gray discharge during your period is not typical and usually points to bacterial vaginosis, an overgrowth of certain bacteria in the vagina. It often comes with a fishy smell that gets stronger after sex. Gray discharge deserves a visit to your healthcare provider, as bacterial vaginosis is easily treated but can cause complications if left alone.
Blood Clots and What Size Matters
Passing small clots during your period is completely normal, especially on heavier days. Clots the size of a dime or a quarter are common and not a concern. Your body releases anticoagulants to keep menstrual blood flowing smoothly, but on heavy days, the blood sometimes moves faster than those anticoagulants can work, so small clots form.
The line to watch is clot size and frequency. Passing golf ball-sized clots, or passing large clots every couple of hours, signals unusually heavy bleeding that should be evaluated. Similarly, soaking through a pad or tampon every one to two hours, or bleeding for more than seven days, falls outside the normal range. A typical period uses three to six pads or tampons per day and lasts seven days or fewer.
When Color Actually Signals a Problem
For the most part, color alone doesn’t indicate anything wrong. The colors that do warrant attention are orange and gray, specifically when paired with odor, itching, or irritation. Black blood with a foul smell (as opposed to the mild metallic scent of regular period blood) also needs evaluation, since it can point to a retained foreign object or, rarely, a cervical blockage.
What matters more than color is the overall pattern of your cycle. Periods that suddenly become much heavier, much lighter, or more irregular than what’s normal for you are worth tracking. Going more than three months without a period (outside of pregnancy) is a threshold that gynecological guidelines flag for evaluation, since cycles that irregular can reflect hormonal or structural issues that benefit from early attention.
The most useful thing you can do is learn your own baseline. Track the colors, flow levels, and duration you typically see so that genuine changes stand out from normal variation. A period that looks different from your friend’s is almost never a problem. A period that looks dramatically different from your own usual pattern is worth investigating.