Stool Colour: What Each Colour Means and When to Worry
Medically Reviewed by Dr. Pedro Yelamo Vera, MD
Licensed Physician No. 484814280 · Official Medical College of Bizkaia (Spain)Last reviewed: 29 October 2026
Stool colour explained: normal shades, green, yellow, pale, black and red poo, the Bristol stool chart, babies' stools and when to call 112.
You don't have to figure this out alone
Dr. Pedro Yelamo Vera is an independent, bilingual GP licensed in Spain. Book a 15-minute video consultation in English or Spanish for €50, with a private electronic prescription issued under Spanish law when clinically appropriate.
Most stool colour changes come from food, drinks or medicines and settle in a day or two. Any shade of brown, and even green, is normal. Three colours need a closer look: black and tarry, red with blood, and pale or clay-coloured. In a baby, white or very pale stools need a doctor's check today.
- Brown in all shades, and green, are normal. Bile and diet set the colour.
- Black stools are often from iron tablets or bismuth. Black, sticky, tarry stools can mean bleeding higher up the gut.
- Red can be beetroot. Bright red blood is often from piles, but blood for 3 weeks needs a doctor.
- Pale or clay-coloured stools, with dark urine or yellow skin, can mean a liver or bile duct problem.
- A baby with pale, chalky or white stools needs an urgent check.
- Call 112 for heavy bleeding, vomiting blood, or black stools with dizziness or fainting.
Dr. Pedro Yelamo Vera is a GP licensed in Spain (Colegiado No. 484814280).
For a medical emergency, call 112 or go to the nearest local emergency department. Do not wait for a video consultation or an online reply.
What stool colour is normal?
Mayo Clinic says all shades of brown, and even green, are normal. Bile turns from green to brown as it moves through the gut. A colour that stays for several days is worth asking about.
What does each stool colour mean?
| Colour | Common harmless causes | What it can point to |
|---|---|---|
| Green | Leafy greens, green food colouring, iron tablets | Food moving through fast, as in diarrhoea |
| Yellow, greasy, smelly | Very fatty or fried food | Fat not being absorbed, for example coeliac disease |
| Pale, white or clay | Barium from an X-ray, some antacids and anti-diarrhoea medicines | Too little bile: a liver, gallbladder or bile duct problem |
| Black | Iron tablets, bismuth, liquorice, blueberries, black pudding (morcilla) | Bleeding in the stomach or upper gut |
| Red | Beetroot, red food colouring, tomato juice | Bleeding lower down, often from piles |
Is green or yellow poo a problem?
Green stools usually come from food or a stomach bug. Yellow, greasy stools that float and smell very bad are different. Mayo Clinic links them to poor fat absorption, especially with weight loss. See a doctor if they keep coming back. Diarrhoea after a trip is covered in our travellers' diarrhoea page.
What do pale or clay-coloured stools mean?
Stools are brown because of bile. MedlinePlus says pale or clay stools can mean bile is not reaching the gut. Hepatitis, gallstones and a blocked bile duct are causes. Yellow skin (jaundice) and dark urine often come with them. See a doctor within a day or two if your stools stay pale for several days. See one today if you also have yellow skin or eyes, dark urine or pain in the upper right tummy. Our bilirubin guide explains the related blood test.
Is black stool an emergency?
Not always. Iron tablets and bismuth stomach remedies often turn stools black or dark green. Blood from the stomach looks different: black, sticky and tar-like, with a strong smell. Doctors call this melena. MedlinePlus says peptic ulcers are the most common cause. Blood thinners, aspirin and anti-inflammatory painkillers raise the risk.
- Black, tarry stool and you feel well: get a medical check today. The NHS advises urgent help for black poo.
- Black, tarry stool with dizziness, fainting, a fast heartbeat or vomiting blood: call 112.
What does blood or red in the stool mean?
Beetroot can turn stools and urine red for a day. Real blood has a few patterns, according to the NHS:
- Bright red on the paper or in the water, often with straining: usually piles (haemorrhoids) or a small tear (anal fissure).
- Dark red or maroon blood mixed into the stool: needs an urgent check today.
- Bloody diarrhoea, often with cramps: also urgent. Infection and inflammatory bowel disease are causes.
See a GP if blood has been there for 3 weeks, or your stools have been looser or thinner for 3 weeks. The same goes for unexplained weight loss, and for any blood in a child's poo. Piles are common and treatable; see our haemorrhoids page and our guide to discussing piles with a GP in Spain.
Worried about a change in your stools?
You can book a video visit with a GP licensed in Spain, in English or Spanish. He asks about your symptoms, food and medicines, and tells you whether you need tests or an urgent check.
Is mucus in the stool normal?
A little mucus is normal. Mayo Clinic says more mucus with diarrhoea can come from a gut infection. Mucus with blood, or with tummy pain, can point to Crohn's disease, ulcerative colitis or, rarely, cancer.
What is the Bristol stool chart?
Doctors use it to describe stool shape:
- Type 1: separate hard lumps, like nuts, hard to pass.
- Type 2: sausage-shaped but lumpy.
- Type 3: like a sausage with cracks on the surface.
- Type 4: like a sausage or snake, smooth and soft.
- Type 5: soft blobs with clear-cut edges.
- Type 6: mushy pieces with ragged edges.
- Type 7: watery, with no solid pieces.
The NHS calls types 3 and 4 the healthy range. Types 1 and 2 are typical of constipation, and types 6 and 7 of diarrhoea.
What colour should a baby's poo be?
- First days: meconium, a sticky, tar-like, greenish-black stool. This is normal.
- Breastfed babies: soft, yellow, like light mustard with seed-like bits.
- Formula-fed babies: tan or yellow, a little firmer.
- Green, orange and brown can be normal too.
Pale, chalky, grey or white poo in a baby needs a doctor's check today, without waiting, especially with yellow skin or dark urine. Keep a photo for the doctor. It can be a sign of biliary atresia, a rare blocked bile duct. MedlinePlus says signs appear between 2 and 8 weeks of age. Surgery works better before 8 weeks, so do not wait. Red or black poo after the first days also needs a doctor.
Bowel cancer screening in Spain, the UK and the US
Spain's public programme posts a home test for hidden blood in the stool (sangre oculta en heces) every 2 years. It has invited people aged 50 to 69. An order of April 2026 extends it to 74. Regions have up to five years to start, so ask your health centre. A positive result is not a diagnosis; it leads to a colonoscopy.
In England, the NHS offers a home FIT kit every 2 years from 50 to 74. In the US, screening is advised from 45 to 75. Screening is for people without symptoms. If you have bleeding or a change in bowel habit, see a doctor now.
When should you call 112?
- Black, tarry stools with dizziness, fainting, sweating or a racing heart.
- Vomiting blood, or vomit that looks like coffee grounds.
- Heavy bleeding from the bottom: bleeding that will not stop, a red toilet bowl or large clots.
- A baby or child who is pale, floppy or hard to wake.
Do not drive yourself to urgencias.
Talking it through with a doctor by video
Dr. Yelamo is a GP licensed in Spain. He sees adults, children and pregnant patients by video, every day from 07:30 to 20:30 (Spain time). In the visit he will:
- Ask about the colour, how long it has lasted, and other symptoms.
- Go through food, iron and blood thinners, and check for warning signs.
- Explain which tests make sense, such as blood tests or a stool test.
He does not promise any test or prescription before the visit. Where clinically appropriate, following a genuine evaluation. Treatment and prescriptions are issued solely at the doctor's discretion based on evidence-based clinical guidelines.
A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.
See how the Urgent Care video visit works. It lasts 15 minutes and costs €50.
This guide is general information. It does not replace a consultation with your doctor.
Frequently asked questions
What stool colour is normal?
Any shade of brown, and green too. Diet and bile set the colour, and it changes from day to day.
Can iron tablets make stool black?
Yes. Iron tablets and bismuth remedies often turn stools black or very dark green. Black, sticky, tar-like stools are different and need an urgent check.
Why is my poo red after beetroot?
Beetroot pigment can colour stools and urine red for a day or so. If the red does not fade, or you see clots, see a doctor.
What do pale stools and dark urine mean?
Together they suggest bile is not reaching the gut, from a liver, gallbladder or bile duct problem. See a doctor today, especially with yellow skin or eyes.
Is white poo in a baby an emergency?
It needs a doctor's check today, without waiting. Pale, chalky or white stools can be a sign of biliary atresia, which is treated best before 8 weeks of age.
Which Bristol stool type is healthy?
Types 3 and 4: sausage-shaped, smooth or slightly cracked, and easy to pass.
Who gets bowel cancer screening in Spain?
The public programme sends a stool test for hidden blood every 2 years from age 50. It covered 50 to 69 and is being extended to 74 region by region.
Sources
- Mayo Clinic: Stool color, when to worry
- MedlinePlus: Black or tarry stools
- MedlinePlus: Stools, pale or clay-colored
- NHS: Bleeding from the bottom
- MedlinePlus: Biliary atresia
- Ministerio de Sanidad: Colorectal cancer screening (Spanish)
Related guides
Medical Citations & Sources
This content is written and reviewed by a licensed physician with reference to the following official health authorities.
