# Constipation

URL: https://thethyroidologist.com/symptoms/constipation/
Section: Symptoms
Last medically reviewed: 2025-11-01

> Constipation is a recognised hypothyroid symptom — but also caused by diet, medications, and many other conditions. When thyroid testing is worthwhile.

Constipation — infrequent, hard or difficult bowel movements — is common and has many causes. Hypothyroidism is a recognised contributor because thyroid hormone affects gut motility.
It is a non-specific symptom that only suggests thyroid testing when combined with other features.

## Thyroid connection

Hypothyroidism slows intestinal motility, contributing to constipation alongside fatigue, weight gain and cold intolerance. It is a classic but non-specific feature.
Hyperthyroidism more often causes loose stools or diarrhoea — the opposite pattern.

## Other causes

Low fibre or fluid intake, sedentary lifestyle, medications (opioids, iron, some antidepressants, calcium channel blockers), pregnancy, hypothyroidism, diabetes affecting nerves, pelvic floor problems, and irritable bowel syndrome all cause constipation.
In many cases, simple dietary and lifestyle factors are responsible.

## Evaluation

Thyroid testing is reasonable when constipation is accompanied by other hypothyroid features or is new and unexplained. Alarm features — blood in stool, weight loss, severe pain, change in bowel habit in older adults — need prompt evaluation regardless.
Persistent constipation despite lifestyle measures warrants medical review.

## Frequently asked questions

### Can levothyroxine cause constipation?

Rarely — under-replacement can worsen constipation; correct dosing typically improves it. If constipation persists on adequate treatment, other causes should be sought.

### Does hyperthyroidism cause diarrhoea?

Yes — increased gut motility can cause loose stools or diarrhoea, the opposite of hypothyroidism.

### When should constipation worry me?

New constipation with blood, weight loss, severe pain, or in older adults with changed bowel habits needs prompt assessment.

## Disclaimer

The content on this website is for general educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your specific condition.

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Part of The Thyroidologist — https://thethyroidologist.com