Here's the surprise: most of the time, you can't see gallstones in the toilet at all. If you've spotted green or yellowish lumps and wondered what gallstones look like, you're usually looking at something else. Gallstones tend to stay in the gallbladder, and the "stones" people photograph after a so-called flush appear, in many cases, to be formed from the flush itself [1][2].
Gallstones rarely show up in poo. Most stay in the gallbladder, and when one moves it usually causes pain rather than a visible stone. Lumps in the toilet are far more likely to be undigested food, fat or "soap stones" formed during a gallbladder flush [1][2].
What do gallstones look like, and can you pass them?
Gallstones are small stones, usually made of cholesterol, that form in the gallbladder, the little pouch under your liver that stores bile for digesting fat (NHS) [1]. See our digestive system tour and gut and liver connection guide. Gallstones are common: research suggests roughly 10 to 20% of adults in high-income countries have them, depending on the population studied [3], yet NHS guidance notes most people never get symptoms [1].
Small stones can sometimes slip out of the gallbladder into the bile duct. That journey is usually the painful part. A stone that blocks a duct may cause biliary colic: severe, constant pain in the middle of your tummy or under your right ribs that can last from 30 minutes to several hours, and a blockage can sometimes lead to more serious complications such as inflammation of the gallbladder or pancreas [1]. If a tiny stone does reach the bowel, it's likely to be mixed into stool and go unnoticed. Our guide to how long food takes to digest explains how much gets blended on the way through.
So what are the stones people see after a gallbladder flush?
Social media is full of "liver flush" photos: olive oil and citrus juice, then soft green pebbles. In 2005, doctors writing in The Lancet analysed stones passed by one patient after a flush and found no cholesterol, bilirubin or calcium, the usual building blocks of real gallstones [2]. They appeared to be lumps formed from the oil itself. One case can't prove everything, but Mayo Clinic doctors describe the same thing: the lumps are likely oil, juice and other material, and there's no reliable evidence that a cleanse treats gallstones [4].
Flushes aren't risk free either. They may cause sickness, diarrhoea and tummy pain [4], and lots of oil can act as a laxative (see natural laxatives).
What else could those lumps in my poo be?
| What you see | What it might be | Worth knowing |
|---|---|---|
| Soft green or yellow lumps after an olive oil cleanse | Likely "soap stones" made from the oil [2] | Usually soft, but texture alone cannot identify what a lump is |
| Small yellow or brown bits | Undigested food such as sweetcorn, seeds or skins | Very common and usually harmless |
| Greasy, floating, hard to flush poo | Fat not being absorbed well | See our guide to oily stool |
| Pale or clay coloured poo with dark pee | May point to a problem with bile flow [1] | Get urgent advice from a GP or NHS 111; read about pale stool |
Colour and texture shift daily for ordinary reasons, so it helps to know your normal. Start with our healthy stool colour guide, the Bristol Stool Chart guide and why poo sinks or floats. For yellow poo or an unusual smell, see why stool smells different.
Who is more likely to get gallstones?
According to the NHS, you may be more likely to get gallstones if you're over 40, a woman, living with obesity, eating a diet high in fat and low in fibre, losing weight quickly, or living with a condition such as diabetes or Crohn's disease [1]. Diet is only one part of the picture, so it can't on its own explain why someone does or doesn't get gallstones. Our articles on gut health after 40, fibre and gut health and eating for your gut cover the habits behind some of these. Losing weight on a prescribed medicine? See GLP-1 medicines and digestion.
Get urgent help if you notice any of these
- Call 999 or go to A&E if you have sudden, severe tummy pain, pain that spreads to your back while being sick, a very high temperature or feeling hot, cold and shivery, or yellow skin or yellow whites of the eyes [1]
- Ask for an urgent GP appointment or contact NHS 111 if you have tummy pain lasting longer than 30 minutes [1]
Do not drive yourself to A&E. Ask someone to take you or call 999 [1].
Frequently asked questions
What colour are gallstones?
Real gallstones vary. Cholesterol stones, the most common kind, tend to be yellowish or greenish, while pigment stones are usually dark brown or black and smaller [3]. They're typically hard, unlike the soft, waxy lumps seen after a flush. Because gallstones rarely appear in stool, colour, texture or a photo can't reliably identify one; a scan is how they're usually found [1].
Can you pass a gallstone without knowing?
Possibly. Small stones may move through the bile duct with little or no pain, and many people with gallstones never have symptoms at all [1][5]. They're often found by chance during a scan for something else [1]. Pain under your right ribs that settled on its own is worth mentioning to your GP.
Should I try a gallbladder flush?
There's no reliable evidence that a gallbladder or liver flush removes gallstones, and doctors report it can cause sickness, diarrhoea and pain [4]. The "stones" it produces appear to be formed from the oil itself [2]. If you think you have gallstones, speak to your GP, who can arrange an ultrasound scan or blood test [1].
If you've spotted lumps after an olive oil cleanse, they're very likely soap stones rather than gallstones. Small yellow or brown bits are usually undigested food. You can't diagnose gallstones from the toilet, so use the stool health FAQ for context rather than answers. Tummy pain lasting longer than 30 minutes, or pale poo with dark pee, means asking for an urgent GP appointment or contacting NHS 111. Yellow skin or eyes, sudden severe pain, or a very high temperature with shivering means calling 999 or going to A&E [1].
References
- NHS. Gallstones. Page last reviewed 11 August 2025. https://www.nhs.uk/conditions/gallstones/
- Sies CW, Brooker J. Could these be gallstones? The Lancet. 2005;365(9468):1388.
- Lammert F, Gurusamy K, Ko CW, et al. Gallstones. Nature Reviews Disease Primers. 2016;2:16024.
- Mayo Clinic. What is a gallbladder cleanse? Is it an effective way to flush out gallstones? mayoclinic.org
- NHS England. Making a decision about gallstones (shared decision making tool). 2023. england.nhs.uk
This content is for informational purposes only and does not constitute medical advice. If you have concerns about your digestive health, please speak to a qualified healthcare professional.
