Stool Color & Appearance
Most of the time, the color of your poop just reflects what you've eaten. But stool color can occasionally be a useful signal — and a few colors are worth taking seriously. This stool color chart walks through the common shades, what usually causes them, and when a color is a reason to call a doctor.
Stool color chart
| Color | Common causes | What to do |
|---|---|---|
| Brown | Normal — from bile and digestion | No action needed |
| Green | Leafy greens, food coloring, fast transit | Usually harmless |
| Yellow | Fatty or greasy stool, fast transit, diet | Check if persistent or greasy |
| Black / tarry | Iron, bismuth — or bleeding higher in the gut | See a doctor if not from iron/medicine |
| Red | Beets, red food — or bleeding lower in the gut | See a doctor if not clearly dietary |
| Pale / clay | Lack of bile reaching the stool | See a doctor |
Brown: the normal color
Healthy stool is brown. The color comes from bile — a fluid your liver makes to digest fat — and from the breakdown of old red blood cells. As bile travels through the gut it changes color, ending up brown by the time stool leaves the body. Light to dark brown are all within the normal range.
Green poop
Green is one of the most common non-brown colors and is usually harmless. Leafy greens, foods with green or purple dye, and iron supplements can all do it. It can also happen when stool moves through the gut quickly, so bile doesn't have time to fully change color. If green stool is a one-off or clearly food-related, there's normally nothing to worry about. More on green poop →
Yellow poop
Occasional yellow stool is often diet- or transit-related. Persistently yellow, greasy stool that's hard to flush can suggest your body isn't absorbing fat well, which is worth discussing with a doctor — especially if it comes with other digestive symptoms.
Black or tarry stool
Black stool has two very different explanations. Iron supplements and bismuth medicines (like some anti-diarrhea or stomach products) commonly turn stool black and are harmless. But black, sticky, tarry stool can also mean bleeding higher up in the digestive tract. If you aren't taking iron or bismuth, black tarry stool should be evaluated promptly. More on black stool →
Red stool
Red can come from beets, tomato, or red food coloring — or from bleeding lower in the gut. Bright red blood is often from the lower bowel or anus (for example, hemorrhoids), while darker red can come from higher up. Because it can signal bleeding, red stool that isn't clearly from food should always be checked. More on blood in stool →
Pale or clay-colored stool
Stool that is pale, gray, or clay-colored may mean bile isn't reaching the intestine, which can point to a problem with the liver, gallbladder, or bile ducts. Persistent pale stool should be evaluated by a doctor.
When to see a doctor about stool color
- Black, tarry stool when you're not taking iron or bismuth
- Red stool or visible blood that isn't clearly from food
- Pale, gray, or clay-colored stool
- A color change that persists for more than a week or two
- Any color change with pain, weight loss, or feeling unwell
Track color and consistency with PoopID
Color is easy to forget by the time you'd mention it to a doctor. PoopID notes color along with your Bristol Stool type from a photo, so unusual changes are recorded and easy to review — privately, on your iPhone.
- Sources:
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). niddk.nih.gov
- NHS — Bowel symptoms; Blood in stool. nhs.uk
Frequently asked questions
What color of poop is unhealthy?
Black tarry stool (when not from iron or bismuth), red stool or visible blood that isn't clearly dietary, and pale or clay-colored stool are the colors that warrant medical attention.
Why is my poop green?
Usually harmless. Leafy greens, green or purple food dye, iron supplements, or stool moving quickly through the gut (so bile doesn't fully change color) are common causes.
Does black stool always mean bleeding?
No. Iron supplements and bismuth medicines often turn stool black harmlessly. But black, sticky, tarry stool can indicate bleeding higher in the gut, so it should be checked if you aren't taking those.
Is red poop always blood?
Not always — beets, tomatoes, and red dye can cause it. But because red can also mean bleeding lower in the gut, red stool that isn't clearly from food should be evaluated by a doctor.
How long should a color change last before I worry?
A one-off, food-related color is usually fine. A color change that persists beyond a week or two, or that comes with pain, weight loss, or feeling unwell, should be checked.
This article is for general information only and is not medical advice. Consult a qualified healthcare professional about any symptom that concerns you.
In this guide series
- Black Stool: Causes and When to WorryWhat black or tarry stool can mean, common harmless causes, and the red flags that need a doctor.
- Green Poop: Common Causes ExplainedWhy poop turns green - from food to fast transit - and when green stool is worth checking.
- Blood in Stool: Causes and Red FlagsWhat blood in your stool can mean, bright red versus dark, and why it should always be evaluated.
- Yellow Stool: What It Tells YouWhy poop turns yellow or greasy, when it's just diet, and when fatty stool is worth checking.
- Mucus in Stool: Should You Worry?A little mucus in stool is normal - here's what causes it and when more mucus needs a doctor.
- Floating Poop vs Sinking: What It MeansWhether your poop floats or sinks rarely matters - but greasy, floating stool can be a clue.