Do Iron Tablets Cause Constipation?

Quick Answer

Yes, many regular iron tablets can cause constipation, acidity, nausea, stomach pain, or dark stools. This is one of the most common reasons people stop taking iron supplements before their iron levels improve.

Full Answer

Iron tablets can cause constipation in some people, especially when the iron is not well tolerated by the stomach. Conventional iron salts such as ferrous sulphate or ferrous fumarate may irritate the gut in sensitive users. When this happens, people often reduce the dose, skip tablets, or stop completely.

The problem is not only discomfort. If iron is not taken consistently, haemoglobin and ferritin may not improve properly.

Common side effects of iron tablets include constipation, nausea, stomach discomfort, acidity, bloating, and black stools. Black stools can happen with iron use, but if stools are tarry, foul-smelling, or associated with weakness or abdominal pain, medical advice is needed.

To reduce constipation, your doctor may suggest taking iron with food, increasing water and fibre, changing the timing, or switching to a gentler iron formulation.

Chelon contains ferrous bisglycinate, an iron amino acid chelate, with vitamin C. It is designed to be a small, better-tolerated iron tablet and may be suitable for people who struggle with regular iron tablets.