We have all experienced watery poo (diarrhoea) at some point in our lives. This happens when our intestines don't have time to or fail to absorb the water and excess fluid from our stools, causing the waste to pass through your digestive tract too quickly.

There's a few main reasons why. You normally have some warning signs but if you went to the loo expecting business as usual but what  you got was watery poo, there's a few things to think about the causes and how to get your gut back on track.

Don't worry, you're not weird, and you're not broken. Watery poos can be vry very common, and most of the time it's your gut reacting to something pretty boring. And we can help. 

What "watery poo" actually means (diarrhoea)

There's a brilliant little tool called the Bristol Stool Chart (below) that sorts poo into seven types, from rabbit-dropping pellets at one end to full liquid at the other.

 

Number 7 is watery or liquid poo - no solid pieces, all liquid. The one you're aiming for is a Type 3 or 4. Smooth, sausage-shaped, easy to pass, in and out in seconds.If you've never actually looked at the chart, it's two minutes well spent.

Why Your Poo Might Be Liquid-y (Yep, We're Talking Diarrhoea)

If your poo has gone from solid to watery, or you're suddenly making a mad dash to the loo, your gut is trying to tell you something.Diarrhoea happens when food and waste move through your digestive system too quickly, or your gut doesn't absorb enough water.

 

The result? Loose, watery poo, often accompanied by urgency, cramps and that horrible feeling of needing to know exactly where the nearest toilet is.

Most of the time, it comes down to a handful of everyday things:

Something you ate didn't agree with you. A dodgy takeaway, food poisoning, a food intolerance or even something you've eaten plenty of times before. Lactose (found in dairy) can be a common culprit if you're intolerant, while certain artificial sweeteners, particularly sorbitol found in sugar-free gum and sweets, can draw extra water into your bowel and leave you running to the loo.

Coffee, alcohol, or a generous helping of both. Coffee stimulates the muscles in your gut, which can speed things along a little too enthusiastically. Alcohol can also irritate your digestive system and interfere with how your gut absorbs water. If you've had a particularly indulgent weekend, your poo might be paying the price.

Stress and anxiety. Your gut and brain are in constant communication, and when you're feeling anxious, overwhelmed or running on adrenaline, your bowels can suddenly hit the accelerator. This is particularly common in people with IBS. Sometimes you're blaming last night's dinner when the real culprit was a horrible week at work. And stress often brings poor sleep, extra coffee and changes to your eating habits, which don't exactly help matters.

A tummy bug. If your diarrhoea appeared out of nowhere, especially alongside nausea, cramps or vomiting, you could have picked up a stomach bug such as norovirus. These nasty little visitors can make your poo extremely watery, but most cases clear up on their own within a few days. The important thing is keeping hydrated and replacing lost fluids and salts.

A sudden change in diet. Started a health kick? Eating loads more fruit, fibre, smoothies or plant-based foods? While fibre is generally brilliant for gut health, suddenly changing what and how much you eat can upset your usual bowel habits. Certain fermentable carbohydrates, particularly in people with sensitive guts, can also trigger loose stools and diarrhoea.

IBS and a sensitive gut. If watery poo is becoming a regular visitor, particularly alongside bloating, abdominal discomfort and an urgent need to go, IBS with diarrhoea (IBS-D) could be one possible explanation. People with IBS can have more sensitive bowels, and certain foods, stress or hormonal changes may trigger diarrhoea. It's worth getting recurring symptoms checked rather than assuming it's IBS.

Magnesium, vitamin C or changing medication. Taking high doses of magnesium or vitamin C? Both can cause diarrhoea, particularly in larger amounts. Some medications, including antibiotics and certain diabetes treatments, can also cause loose, watery stools.

A little reminder from your gut

Most short-lived bouts of diarrhoea settle on their own, but don't ignore watery poo that keeps coming back. Most of the time, there's nothing to worry about. A day or two of liquid stools after spicy food, a stressful stretch, or a holiday where you ate unusual food is just your gut doing its job.

Keep your water intake up, eat normally, and things tend to firm back up by themselves.If it keeps happening, though, your gut might be trying to tell you something.

Ongoing loose stools can be linked to things like IBS, a food intolerance you haven't pinned down yet, or simply how your own microbiome is getting along. Worth paying attention to. Not worth lying awake over.

Our piece on why you might have diarrhoea all the time goes into the longer-term causes properly.

When to actually book in with your GP

Quick checklist, and please don't read it in a panic. None of this is meant to scare you.  Get an appointment if:

• It's carried on for more than a couple of weeks
• You notice blood
• You're losing weight without meaning to
• It's waking you up in the night
• There's pain that won't ease off

Mushy, porridge or liquid poo can be improved

Gemma was asked for comment on a variety of gut health related topics. This article was updated June 2026. 

Express Article: 'Porridge poo' could be a sign of six health problems, expert shares 

While looking into the toilet bowl after you went for a number two might be the last thing you want to do, your stool could help identify any new health problems.

While the topic of stool can make you feel squeamish, it’s important to look out for anything that is unusual for your, including porridge poo.

Gut expert, Gemma Stuart, from Gut Wealth, said: “If your stool looks like mushy lumps of porridge with soft, ragged edges, for most this is likely the first sign of diarrhoea.