Why does my poop smell so bad?

Is smelly poop normal?

Yes. MedlinePlus says it plainly: stools normally have an unpleasant odor, and most of the time the smell is familiar. It also says diet changes are a normal cause of foul-smelling stools.

So if you had a big, unusual meal yesterday, a strong smell today isn’t a surprise.

What can make it worse?

The MedlinePlus page lists possible medical causes of foul-smelling stools, including:

• intestinal infection
• coeliac disease
• Crohn’s disease and ulcerative colitis (types of IBD)
• malabsorption, where the body doesn’t absorb nutrients properly
• blood in the stool from the stomach or intestine

That list sounds scary out of context. The key word is change: a smell that’s unusual for you, sticks around and comes with other symptoms.

What about very specific smells?

People search for poop that smells like sulfur, eggs, metal and more. The sources we rely on don’t tie specific smells to specific causes, so we won’t. If a new smell sticks around, note it and mention it to your GP along with anything else you’ve noticed.

When should I talk to a doctor?

MedlinePlus says to contact a provider if you have:

• black or pale stools often
• blood in the stool
• chills, fever or cramping
• belly pain
• weight loss
• changes in stool linked to diet

It also says that if you have diarrhea, drink more fluids so you don’t get dehydrated.

A few combinations are worth knowing:

• Floating, greasy and foul-smelling, especially with weight loss, may point to fat malabsorption (MedlinePlus). See floating poop.
• Black, tarry and foul-smelling can be a sign of bleeding high in the gut (MedlinePlus). Get urgent advice. See black poop.
• Diarrhea that smells particularly unpleasant, with bloating, tiredness or weight loss, is listed by the NHS among coeliac disease symptoms.

What will a doctor ask?

MedlinePlus lists questions like: When did you first notice the change? Are your stools pale or black? Are they hard to flush? What have you eaten recently? Does a change in diet make the smell better or worse?

That last one is where a log earns its keep.

Thu 19:00  Dinner (photo): garlic prawns, broccoli, white wine
Fri 08:15  Poop: type 5
Fri 08:15  Paper note: really strong smell
Sat 08:30  Poop: type 4
Sat 08:30  Paper note: normal

Questions to ask yourself

Everyone’s poop smells, so the useful question is whether yours has changed. Did the smell shift after a new food, a course of antibiotics, a trip or a stomach bug? Is it worse with certain meals, like eggs, cabbage or a heavy takeaway? Is the poop also greasy, floating, loose or paler than usual? Write down what changed and when, and log your poops with their Bristol type for a week or two. A smell that tracks with food is usually just food. A new smell that sticks around with other changes is a good reason to talk to a GP.

Wrap-up

Smelly poop is part of being human, and diet is usually behind the bad days. If a really unusual smell sticks around, or comes with blood, fever, pain, weight loss, or black or pale stools, that’s your cue to see a doctor. Bring your notes; they’ll help.