Blood in stool: causes, what it looks like and when to see a GP

The NHS says the colour and other symptoms can give an idea of the cause, but that you should not self-diagnose and should see a GP if you are worried. Bleeding can come from the anus, the bowel or higher in the gut. The table sets out the causes the NHS lists, grouped by what you notice.

Poo can look as though it is mixed with blood if you have eaten a lot of red or purple foods such as tomatoes and beetroot, and can look very dark or black if you take iron tablets or eat a lot of dark foods such as liquorice and blueberries. The NHS says these can sometimes be a sign of something else and a GP can do a test to check.

The NHS groups bleeding by colour. Bright red blood on toilet paper, streaks on the poo or pink toilet water usually has a cause near the end of the bowel, such as piles or an anal fissure. Blood mixed in the poo, with changes in bowel habit or slime, can have other causes including polyps, inflammatory bowel disease or bowel cancer.

Very dark or black poo, or dark red poo, can be a sign of bleeding higher up, from the stomach or gut. The NHS says to ask for an urgent GP appointment or get help from NHS 111 if your poo is black or dark red or you have bloody diarrhoea.

The NHS says you might be bleeding from the bottom if you have blood on your toilet paper, red streaks on the outside of your poo, pink water in the toilet bowl, blood in your poo or bloody diarrhoea, or very dark poo. Other symptoms often help point to the cause.

• Pain when pooing, an itchy bottom or lumps, which can suggest piles or a fissure.

• Tummy cramps, pain and bloating with bloody diarrhoea, which can suggest inflammatory bowel disease.

• A change in how often you poo or how it looks, such as looser poo, diarrhoea or constipation.

• Tiredness, shortness of breath or weight loss for no reason, which the NHS lists among bowel cancer symptoms.

The NHS says piles (haemorrhoids) are lumps inside and around the anus that often get better on their own after a few days. Symptoms include bright red blood after you poo, an itchy anus, mucus in your underwear and lumps or pain around the anus. Self-care includes drinking lots of fluid, eating plenty of fibre, taking paracetamol for pain, a warm bath and keeping the area clean and dry. It says not to take ibuprofen if your piles are bleeding or painkillers that contain codeine.

An anal fissure is a small tear in the anus that causes sharp pain when you poo, burning pain afterwards and bright red blood on the toilet paper or in the toilet. The NHS says it usually gets better on its own, and to see a GP if it is getting worse or there is no improvement after 7 days of treating it yourself. The NHS says painless bleeding from the bottom with piles needs an urgent GP appointment or NHS 111.

The NHS says bleeding from the bottom is sometimes a sign of bowel cancer. Symptoms of bowel cancer may include changes in your poo (softer poo, diarrhoea or constipation not usual for you), needing to poo more or less often, blood in your poo that may look red or black, often feeling like you need to poo, tummy pain, a lump in the tummy, bloating, weight loss without trying, and feeling very tired or short of breath.

It also says some of these symptoms are very common and can be caused by other conditions, so having them does not definitely mean you have bowel cancer, but it is important to get checked. If it is cancer, finding it early can make it easier to treat.

The NHS says a GP will check what is causing the bleeding. They might check your bottom with a gloved finger (a rectal examination), ask for a sample of poo for testing, or refer you to a specialist for tests. The doctor will ask about your symptoms, general health, medical history and family history of bowel cancer.

You may be given a bowel cancer screening home test kit, called a faecal immunochemical test (FIT), to send a small sample of poo to a lab to check whether you are bleeding from your bowel. The NHS says you may also have a blood test, and that if the GP thinks you have symptoms that could be cancer you may get an urgent referral, which does not definitely mean you have cancer.

The main test for bowel cancer is a colonoscopy, a thin flexible tube with a camera used to look inside your bowel. You will be offered a sedative and painkillers, and a small sample of the lining may be taken.

Go to A&E or call 999 if you are bleeding non-stop from your bottom, or there is a lot of blood, for example the toilet water turns red or you see large blood clots. Do not drive yourself; ask someone to drive you or call 999 for an ambulance.

Ask for an urgent GP appointment or get help from NHS 111 if your poo is black or dark red, or you have bloody diarrhoea. See a GP if your child has blood in their poo, you have had blood in your poo for 3 weeks, your poo has been softer, thinner or longer than normal for 3 weeks, you are in a lot of pain around the bottom, you have a pain or lump in your tummy, you have been more tired than usual or you have lost weight for no reason.

The NHS says to see a GP if your child has blood in their poo. It notes that anal fissures are more common in young children and that constipation is a common cause of fissures in children. Do not assume it is a fissure without a medical check.

On the NHS, the first step is your GP, who can examine you, arrange a FIT test and refer you urgently if bowel cancer is a possibility. Colonoscopy and other tests are arranged through gastroenterology or colorectal services.

Some people choose a private colorectal surgeon or gastroenterologist for faster access to examination or colonoscopy. If you do, ask for results to be shared with your GP and keep any urgent NHS referral in place until a diagnosis is made.