Does aspirin cause diarrhea?
Yes. Aspirin can cause gastrointestinal side effects, including diarrhea. This is usually due to irritation of the stomach and intestines and effects on the gastrointestinal system. Aspirin and other NSAID-type medicines are commonly associated with GI symptoms such as stomach pain, nausea, and diarrhea in some people.
Why would aspirin lead to diarrhea?
Aspirin can irritate the lining of the digestive tract and can affect prostaglandins, which normally help protect the stomach and support normal gut function. In some people, that irritation and altered gut signaling can lead to looser stools or diarrhea.
Is diarrhea more likely with certain types of aspirin?
Diarrhea can happen with any oral aspirin, but the risk of GI side effects is often higher with:
- Higher doses than low-dose “baby aspirin”
- Taking it on an empty stomach
- A history of stomach/intestinal irritation or ulcer disease
- Combining aspirin with other GI-irritating medicines (such as other NSAIDs)
When should you stop aspirin and get medical help?
Get urgent medical care if diarrhea comes with red flags such as:
- Blood in the stool or black/tarry stools
- Severe or worsening abdominal pain
- Signs of dehydration (dizziness, fainting, very dry mouth, reduced urination)
- Fever or diarrhea that lasts more than a couple of days
- Black, tarry stool (can indicate bleeding)
If you have frequent diarrhea after starting aspirin or you’re taking it daily, contact a clinician to discuss whether you should switch strategies or adjust dose.
What can you do if aspirin is causing diarrhea?
Common practical steps include:
- Taking aspirin with food (unless your prescriber told you otherwise)
- Avoiding other NSAIDs at the same time unless directed
- Reviewing your full medication list with a clinician or pharmacist
Do not stop aspirin that you were prescribed for heart/stroke prevention without asking the prescriber first, because the risks of stopping can be serious for some people.
Could something else be causing the diarrhea?
Yes. Diarrhea after aspirin might also be related to:
- An infection or food-related illness
- Another medication started around the same time (common culprits include antibiotics, metformin, magnesium-containing products, and some supplements)
- Acid reflux/irritation conditions that overlap with NSAID side effects
If diarrhea started right after beginning or increasing aspirin, the timing makes aspirin a plausible cause.
Sources
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