Period blood colour: what bright red period blood, brown blood and the other shades actually mean

Period blood is not one colour, and it rarely stays the same colour from the first day to the last. Most people notice bright red on the heaviest first days, dark red on the days either side of those, and brown or rust at the very end. That sequence is so common that it is worth saying plainly at the outset: in a period that is otherwise behaving normally, colour is one of the least informative things about it. It describes the journey the blood has made on its way out rather than anything about the womb it came from.

This article explains the single mechanism behind almost the whole question, then goes through the shades one at a time: bright red, dark red, brown, black, pink, orange and grey. It sets out what each usually means, when in the period it tends to appear, and whether it needs anything doing. It is honest about the two that are not really about blood at all, grey discharge and an orange loss with an odour, because those point towards infection rather than menstruation. It also covers clots, what colour cannot tell you, and the findings that need assessment the same day.

What period blood colour actually reflects

Menstrual loss is a mixture of blood, broken down lining of the womb, cervical mucus and vaginal fluid, and that mixture does not change much from one day of a period to the next. What does change is how quickly it leaves and how long it sits before it does. Haemoglobin, the iron containing protein that makes blood red, darkens as the iron in it oxidises. Blood that travels out quickly has had little time to oxidise and looks bright red. Blood that has pooled in the uterus or the vagina for hours looks dark red, brown or almost black by the time it appears.

That is very nearly the entire explanation. Fresh and fast looks bright red; slow and older looks brown or almost black. Colour therefore tracks the speed of the flow rather than what the loss is made of, which is why the same woman sees red on her heaviest day and brown on her lightest without anything having changed inside her. It also explains why brown loss clusters at the beginning and the end of a period, when flow is slow enough for blood to linger, and why a night in bed is often followed by a darker first wipe in the morning.

Two ideas that circulate widely are worth correcting here. Dark or brown menstrual loss is not blood left over from a previous month, and the uterus does not store an old bleed. Nor is darker blood dirtier, more toxic or in need of flushing out; oxidised haemoglobin is chemically altered, not contaminated. Colour sits alongside odour and consistency as something to describe to your own doctor if it has changed and stayed changed, rather than as a finding that means anything by itself.

How colour normally changes across a period

NHS information describes a period lasting between 2 and 7 days, usually about 5, with the bleeding heaviest in the first couple of days and total loss across the whole bleed in the region of 20 to 90 mL. It also states that when the period is at its heaviest the blood will be red, and that on lighter days it may be pink or brown. That is the arc most people recognise: red through the heaviest first days, then pink, brown or rust as it tails off. A brown smear in the day or so before the flow proper arrives is common as well, although it is not part of the NHS description.

The order is not fixed, and plenty of ordinary periods do not follow it. Some begin bright red within the first hour. Some produce brown loss for a day before the flow proper arrives, which counts as spotting rather than as day one of the cycle and is worth recording separately if you are tracking cycle length. Some stay dark throughout. Someone using a hormonal method of contraception may see almost nothing but brown, because a thinner lining sheds slowly. None of those patterns is a problem in itself.

Posture and timing matter more than most people expect. Lying down for several hours slows the exit of blood, so the first loss after sleeping is often the darkest of the day, and a long journey spent sitting still does the same thing. A heavy day with cramping tends to produce brighter red, because the uterus is contracting and emptying faster. If you want to compare one period with another, compare how many days it lasted and what products were needed, not the shade on a particular morning.

Bleeding that needs a doctor, and the features that need one today

Almost every colour described on this page has an ordinary explanation, and most need nothing beyond noticing. A small number of situations do not, and they belong here rather than at the end, because the gap between a symptom starting and being assessed is what changes how it turns out. Almost none of the findings below is identified by its colour; the one exception is the last, which is about discharge rather than menstrual blood. They are listed by what is happening alongside the bleed, and each one says how quickly it needs acting on. If any of them applies to you, act on it rather than reading on.

• Soaking through a pad or a tampon within an hour, hour after hour, or bleeding through clothes or bedding. This needs assessment the same day, and immediately if you also feel faint, dizzy or breathless.
• Clots larger than about 2.5 cm across, particularly if they keep coming. NHS information uses about 2.5 cm as the marker, and ACOG material describes a slightly smaller size, about 2.4 cm across. Report it rather than waiting for the next period to see whether it happens again.
• Any bleeding at all in a known or possible pregnancy, whatever the colour and however light. Contact your own doctor, an early pregnancy assessment service where one is available, or an emergency department the same day.
• One sided lower abdominal pain with a light, dark or watery bleed in anyone who could be pregnant. Seek assessment today whether or not a pregnancy test has been done, because a test can still be negative very early. Shoulder tip pain, feeling faint, collapse or severe abdominal pain means calling the emergency services now, because these can mean a ruptured ectopic pregnancy.
• Any bleeding after the menopause, meaning after a full year without periods, even a single episode of light brown or pink loss. This is assessed promptly in its own right.
• Bleeding that lasts beyond its usual length for you, or beyond about 7 days, bleeding between periods, or bleeding after sex. Arrange an appointment rather than watching it for months.
• Period pain that is severe, that is not controlled by ordinary painkillers, or that has become worse than your usual. Arrange an appointment; this is assessed on the pain rather than on the colour or the amount of the bleeding.
• Grey vaginal loss, or an orange or yellow loss with an odour, or with soreness or itching. These point towards infection rather than menstruation, and they need an appointment rather than treating at home. If there is also fever, or pelvic or lower abdominal pain, seek assessment the same day, because that combination can mean infection of the womb and tubes (pelvic inflammatory disease), which does better the earlier treatment starts.

Most of what is listed above turns out to have a harmless explanation once it has been looked at, and the point of the list is that the question cannot be answered from a phone screen. The emergency features are the exception: shoulder tip pain, feeling faint, collapse or severe abdominal pain in anyone who could be pregnant mean calling the emergency services now, because in that situation something may already have gone wrong. In pregnancy in particular, do not wait to see whether brown loss turns red or settles overnight. The colour will not tell you which of several very different situations you are in, and only assessment will.

Bright red period blood

Bright red is the colour people search for most often, and in the middle of a period it is the least remarkable of all. It simply means blood is leaving quickly enough to arrive without having oxidised. It is therefore the expected colour on the heaviest day or two, and it is also the colour of a period that starts abruptly rather than easing in. Bright red loss that comes with cramping usually reflects a uterus contracting and emptying quickly, and the colour itself is not a concern. The pain is a separate question: period pain that is severe, that stops you doing ordinary things, that does not settle with ordinary painkillers, or that has become worse than it used to be should be raised with your own doctor whatever colour the bleeding is.

Bright red at times other than a period is a different question, and it is the timing rather than the shade that makes it worth raising. Fresh red bleeding between periods, after sex, in pregnancy, or at any point after the menopause is assessed on its own terms. The same applies to fresh red loss that soaks through protection quickly or that carries clots. In each of those situations the information a doctor needs is when it happened, how much there was and what came with it.

If your periods have always been bright red from start to finish, that is your own pattern and not a finding. If a period that used to darken as it tailed off is now bright red throughout and heavier than it was, the change in volume is the thing to mention to your doctor, not the change in colour. If the change has gone the other way, the article on a period that is lighter than usual covers that ground.

Dark red period blood

Dark red, sometimes described as burgundy or maroon, is the middle of the range. It is blood that has oxidised a little, usually because it sat in the vagina or the cervical canal for a few hours before appearing. It turns up most reliably on waking, after a long spell of sitting still, and on the days either side of the heaviest flow, when the rate of loss is falling but has not yet reduced to a trickle.

In a period that is otherwise ordinary in length and volume, dark red needs nothing at all. It is sometimes accompanied by small clots, because slower flow gives blood time to coagulate before it leaves, and small clots in dark loss are a matter of physics rather than of disease. The questions worth asking are about the whole bleed rather than the shade: has it become longer, heavier, more painful or less predictable than your own usual pattern.

Dark red bleeding in pregnancy is handled differently, and that difference matters. There is no shade of bleeding in pregnancy that can be classed as reassuring from home. Dark red loss can accompany a pregnancy that continues perfectly well, and it can accompany a miscarriage or an ectopic pregnancy, and those situations cannot be separated by looking. That is the reason any bleeding in pregnancy is assessed the same day rather than watched for a pattern.

Brown and almost black period blood

Brown and near black loss sits at the most oxidised end of the range, and in the great majority of cases it is simply the slowest moving blood of the period. It is the usual colour of the last day, of the brown smear that precedes a period by a day, and of the first wipe after a night's sleep. Thick, almost black loss on a heavy day is often a small clot that has broken up on its way out rather than anything different in kind.

Brown loss outside a period has a long list of ordinary explanations: the days after ovulation in some cycles, the first months on a hormonal method of contraception, the perimenopausal years when cycles become erratic, the days after a cervical screening test or another procedure, and, in very early pregnancy, the light bleeding sometimes called implantation bleeding, which ACOG describes as spotting 1 to 2 weeks after fertilisation. Bleeding in a possible pregnancy cannot be identified as implantation bleeding at the time, so it is assessed the same day whatever it looks like. There is more detail in the articles on spotting before a period and on loss in the days after a period ends.

Brown becomes worth raising when it persists rather than when it appears. Brown loss that continues for days between periods, that arrives after sex, that smells unpleasant, or that happens at all after the menopause should be described to a doctor, and brown loss with fever or pelvic pain should be assessed the same day. Prolonged brown loss can reflect a polyp, a lining that is shedding incompletely, an infection or a cause in the cervix, and these are distinguished by examination and imaging rather than by shade.

Pink and orange period blood

Pink loss is blood diluted by something else, usually cervical mucus or vaginal fluid, which is why it belongs to the very light days at either end of a period and to spotting between periods. It is also common on hormonal contraception and in the weeks after starting a method that thins the lining of the womb. Pink loss after sex is common too, usually because the cervix has been touched, but bleeding after sex is assessed in its own right rather than explained by its colour, so it still needs an appointment. A period that is pink and scanty throughout is more a question about volume than about colour.

Orange loss is also blood mixed with cervical fluid, and when it is thin, odourless and confined to the beginning or the end of a bleed it carries no particular meaning. Orange that is thicker, that has an odour, or that comes with itching, soreness, pain on passing urine or pelvic discomfort is a different matter, because that combination points towards an infection of the vagina or the cervix rather than towards menstrual blood at all, and it needs assessment.

The practical rule for both colours is to look at what accompanies them. Pink or orange loss on its own, in someone who feels well, at the edges of a period, is part of ordinary variation. The same colours with an odour, with discomfort, or appearing persistently between periods need an appointment, and with fever or pelvic pain they need assessment the same day rather than a routine appointment. If odour is the main change you have noticed, describe it to your own doctor or a sexual health service, because odour is assessed alongside the discharge itself rather than by its colour.

Grey discharge: the one that is not about blood

Grey is the shade on this list that should not be filed under period colour at all. A thin, watery, greyish white vaginal discharge with a strong fishy smell, often more noticeable after sex, is the description NHS information gives for bacterial vaginosis, an imbalance of the bacteria that normally live in the vagina. It is not a menstrual colour and not a sign that blood has changed. It is a discharge, and it needs assessment rather than observation.

Two points are worth making plainly. Many women who have it notice nothing at all, so an absence of symptoms says little either way, and it is not classed as a sexually transmitted infection, although sexual activity can trigger it. Treatment is an antibiotic prescribed after assessment. This is one of the situations where buying something over the counter and treating yourself is a poor idea, because the conditions that produce grey, white, yellow and green discharge are managed differently from one another.

Grey discharge around the time of a period is easily missed, because it gets attributed to the bleed. If you notice grey loss, a fishy odour, or a discharge that has changed in colour and consistency and stayed changed, mention it to your own doctor or a sexual health service rather than waiting for the next cycle. Assessment is quick, and it also matters in pregnancy, where this imbalance is treated rather than watched.

The colours side by side

No table diagnoses anything, and the rows below overlap: the same shade appears in more than one situation, and several of them can be present in the same cycle. What a summary helps with is knowing what to describe at an appointment. The columns set out when in the bleed each colour usually turns up, what it usually reflects, and whether it needs anything beyond being noted.

Two rows deserve repeating, because they are the ones most often rationalised away. In pregnancy and after the menopause, colour drops out of the assessment entirely. A single episode of light brown loss carries the same instruction as fresh red bleeding in both of those situations, which is to be assessed rather than interpreted at home.

Clots: what is expected, and what is not

Small clots are a normal part of menstruation and not a sign that anything is wrong. The uterus releases substances that keep menstrual blood from coagulating as it leaves, and when the flow is faster than those substances can keep pace with, some of it clots. That is why clots cluster on the heaviest days, why they are commonest overnight, and why they are often darker than the blood around them. A period with a few small clots on the first or second day is an ordinary period.

• Size is the first thing that matters. NHS information uses clots larger than about 2.5 cm across as one marker of a heavy period, while ACOG material describes a slightly smaller size, about 2.4 cm across. The two descriptions are close but not identical, which is a reminder that these are prompts to seek advice rather than diagnostic cut offs.
• How persistent they are matters as much as how big they are. An occasional clot on the heaviest morning is a different story from clots appearing throughout every period for several cycles in a row.
• What comes with them matters most. Large clots alongside soaking through protection within an hour, hour after hour, need assessment the same day, and immediately if you also feel faint, dizzy or breathless. Tiredness or breathlessness between periods points towards blood loss heavy enough to need a blood count rather than towards the clots themselves.
• Clots in pregnancy, or passing tissue rather than clot, are assessed the same day. Appearance is not used to judge them, and that includes a cast of tissue passed in one piece, which is frightening to see and needs a doctor to interpret.

NICE guidance defines heavy menstrual bleeding by its effect on the woman, as blood loss that interferes with her physical, emotional, social and material quality of life, rather than by a measured volume. ACOG patient information instead sets out practical markers: bleeding lasting more than 7 days, soaking through a pad or tampon every hour for several hours in a row, and clots about 2.4 cm across or larger. If clots, flooding or the number of products needed are interfering with work, sleep, exercise or travel, that is sufficient reason to be assessed, whatever any measured threshold suggests. Your own doctor can then look for the common explanations, several of which are straightforward to treat.

What period blood colour does not tell you

This is the part that is least often written down and the most useful. Colour does not make a diagnosis. There is no shade that identifies fibroids, endometriosis, polyps, adenomyosis, a thyroid problem or a bleeding disorder, and no shade that excludes them either. All of those are found through the history, examination, blood tests and imaging that a doctor arranges, and what prompts that assessment is almost always volume, duration, timing or pain rather than colour.

Colour says nothing about fertility. Brown loss at the end of a period does not indicate a thin lining, a hormonal problem or a reduced chance of conceiving, and bright red loss does not indicate the opposite. Nor does either colour show whether ovulation happened in that cycle. The features of a cycle that carry information about ovulation are its regularity and its length, not the shade of the bleed, and they are interpreted with your own doctor rather than from a tracking app.

Colour also cannot separate a period from early pregnancy bleeding, and this is the most consequential of its limits. Implantation bleeding, a threatened miscarriage, a miscarriage in progress and an ectopic pregnancy can all produce pink, brown, dark red or bright red loss, and so can an entirely ordinary period. What distinguishes them is a pregnancy test and, where there are symptoms, an assessment. Anyone who could be pregnant and has a bleed that is out of character should test rather than interpret.

Where the judgement belongs

The practical conclusion is that colour is worth noticing and rarely worth worrying about. What your own doctor will ask for is the pattern: how many days you bleed, how that compares with your usual, what products are needed and how often they are changed, where the pain sits, whether anything happens between periods or after sex, what contraception you use, and whether pregnancy is possible. Colour appears in that conversation as a descriptive detail rather than as the finding that drives it.

Where a bleed does need looking into, assessment is proportionate and usually quick. It begins with the history and, where relevant, a pregnancy test. An examination is offered where there are symptoms beyond the heavy bleeding itself, and NICE allows treatment to be started without one where the history alone suggests a low risk of another cause. The same guidance advises that a full blood count is carried out for everyone with heavy menstrual bleeding, and advises against thyroid testing unless there are other signs or symptoms of thyroid disease, with clotting studies considered where the heavy bleeding has been present since periods started and there is a personal or family history of bleeding easily. A pelvic ultrasound looks at the uterus and the ovaries, and hysteroscopy inspects the cavity directly where a polyp or a lining problem is suspected.

Bleeding after the menopause is the one situation handled differently from everything above: it is assessed promptly whatever its colour or amount, because although the great majority of cases have a benign cause, examination is how a cancer of the womb or the cervix is ruled out. Nothing written here replaces that assessment, or the judgement of the doctor who knows your history, can examine you, and can set the bleeding against your age, your cycle and your plans.

Related Reading

• Decidual cast: passing the womb lining in one piece
• Why is my period so light? Causes, assessment and what it means for fertility
• Spotting before your period: causes, patterns and when to seek assessment
• Discharge after period: brown, white, clear and what is not expected
• Cramps but no period: what causes it and when it needs assessing

Sources and references

This article is supported by the following independent, authoritative sources:

• NHS (UK), Periods
• NHS (UK), Heavy periods
• ACOG (American College of Obstetricians and Gynecologists), Heavy menstrual bleeding
• ACOG, Bleeding during pregnancy
• NICE (UK), Heavy menstrual bleeding: assessment and management (NG88)
• NHS (UK), Bacterial vaginosis