Vitamins that can cause constipation: what to know

Constipation can mean hard stools, straining, fewer bowel movements or a feeling that the bowel has not emptied. Iron products are a frequent trigger; some formulations and combined supplements are more difficult to tolerate than others. The symptom can also be influenced by low fluid intake, reduced activity, dietary change, medicines, thyroid disease or irritable bowel syndrome. Check the label and the timing of symptoms rather than assuming the supplement is the only cause.

Drink fluids regularly if you have not been told to restrict them, increase fibre gradually, and include gentle activity as tolerated. Do not stop prescribed iron or alter its dose without speaking with the prescriber. They may recommend a different formulation, timing or bowel treatment after considering why iron was prescribed. A nutrition counsellor can help adapt meals without worsening bloating. Avoid repeated laxative use without advice.

Seek prompt medical care for severe or persistent abdominal pain, vomiting, a swollen abdomen, blood in the stool, black tarry stool, fever, or inability to pass stool and gas. Arrange review when constipation continues despite self-care, begins after a new supplement, or is accompanied by unexplained weight loss or marked tiredness. Assessment may consider dehydration, thyroid disease or bowel conditions.

Is this supplement necessary, and could another formulation suit me? How much fluid and fibre are appropriate for my health? Do I need tests for anaemia or thyroid problems? Which bowel treatment is safe with my medicines?