Why Does Taking Iron Supplements Cause Constipation?

By Yashika Goel
01 Jul 2025, 19:00 IST

Iron is an important mineral for our body, which helps in the formation of haemoglobin in the body. Iron deficiency can lead to dizziness and fatigue. But taking iron supplements causes constipation in many people. Tap to know the reason!

Why does iron deficiency happen?

Iron deficiency is more common in women, due to which they suffer from anaemia. It is because they bleed every month, and it can also be genetic in some cases.

Why does constipation occur after taking iron tablets?

People often suffer from constipation after taking these supplements. It is because the body can only absorb 10 or 15 per cent of the iron.

Unabsorbed iron

Iron supplements contain more iron than the body can absorb immediately. The rest of the iron remains in the intestines, which affects gut bacteria and slows down digestion. This leads to increased gas, bloating and constipation.

Dehydration

Excess iron in the stomach draws water from the intestines, which causes dehydration and water imbalance in the body. It makes stool harder to pass.

Changes in gut microbiome

Iron supplements disturb gut bacteria, which slow the process of regular bowel movements, causing constipation.

What to do if you get constipation?

Take an iron supplement once in two days. Drink 3-4 litres of water throughout the day and take fibre fibre-rich diet such as chia seeds, jeera water, fruits and leafy vegetables.

Information Credits

This information is taken from the trusted health website MedicalNews Today. However, it is always advisable to consult a doctor for proper prescriptions and the consequences of supplements.