Rahul Singh Rahul Singh Asked 8 months ago

Can underactive thyroid cause diarrhea?

My brother has an underactive thyroid, and lately he's been having frequent bouts of diarrhea. We thought it usually caused constipation, so we're confused. Can underactive thyroid sometimes cause diarrhea?

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8 answers

Saji Joseph Saji Joseph Joined Jan 2026 8 months ago
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Usually, an underactive thyroid causes constipation because it slows down your digestive system. However, if you are already on thyroid medication, diarrhea can sometimes mean your dosage is too high and you're slipping into hyperthyroidism. You should get a fresh TSH test done to verify.

Sujata Sen Sujata Sen Joined Jan 2026 8 months ago

Normally, hypothyroidism causes constipation, but I actually experienced severe diarrhea when my thyroid dose was set too high by my doctor. If you are having stomach issues, check your latest reports. Make sure to consult your endocrinologist to adjust your daily tablet dose.

Kunal Grover Kunal Grover Joined Jan 2026 8 months ago

Hypothyroidism usually makes your bowels lazy, but sometimes our bodies love to confuse us! If you're running to the washroom constantly, you might have eaten something bad or your thyroid meds are working a bit too hard. Don't panic, just get your levels checked.

Rajesh Gupta Rajesh Gupta Joined Apr 2026 7 months ago

While thyroid itself rarely causes diarrhea directly, changes in your medicine can definitely affect your stomach. For now, stick to light homemade food like curd rice or khichdi and avoid heavy spices. Definitely visit your doctor to see if your dosage needs a change.

Ananya Joshi Ananya Joshi Joined Feb 2026 8 months ago

I had severe diarrhea that I ignored, thinking it was just a stomach bug, but it turned out my thyroid dose was way too high and causing heart palpitations too. Please don't ignore persistent loose motions. Get a doctor to look at your thyroid levels and symptoms immediately.

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Consult a gastroenterologist

Amit Saxena Amit Saxena Joined Feb 2026 8 months ago

Don't believe people online who tell you to drink random herbal decoctions for this. Diarrhea is not a typical symptom of an underactive thyroid, though it can happen due to medication mismatch. Go get a proper blood test done and consult a verified doctor.

Meera Krishnan Meera Krishnan Joined Feb 2026 8 months ago

I can only speak from my own experience, but when my thyroid was underactive, I actually had the opposite issue of constipation. When I did get diarrhea, it was because my medicine dose was too high. It is always best to let a specialist handle the details.

Deepak Raj Deepak Raj Joined Mar 2026 7 months ago

Yes, it is rare but can happen, especially if your thyroid medication dose is currently too high. Get your blood tested.

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