Can I take ferrous sulfate while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about ferrous sulfate.
In short
Pregnancy: If blood tests show your iron levels are low, your doctor or midwife may advise you to take an iron supplement (ferrous sulfate) in pregnancy.
Breastfeeding: Ferrous sulfate can usually be taken during breastfeeding.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- Iron supplements are safe to take while pregnant, and treating low iron is important to keep you and your baby healthy.
- Constipation and piles (haemorrhoids) are common if you take iron supplements during pregnancy.
- A doctor, pharmacist or midwife can advise you on how to prevent them.
- If you do get constipation or piles, ask a doctor, midwife or pharmacist how best to treat them.
Breastfeeding
- Iron, including ferrous sulfate, is naturally found in breast milk.
- Taking an iron supplement does not change how much iron gets into your breast milk or reaches your baby.
- So iron supplements are very unlikely to give your baby side effects.
- However, if your baby's iron levels are also low, your baby will need their own treatment, because your supplements will not change their levels.
When to get help
- Contact your doctor, pharmacist, health visitor or midwife if your baby is feeding less well than normal, is constipated or has diarrhoea, or if anything else about your baby worries you.
Talk to your doctor or pharmacist
This page is educational, not advice for your own situation. Talk to your doctor, midwife or pharmacist before you start, stop or change any medicine in pregnancy or while breastfeeding.
The details: what each source says
Ferrous sulfate in pregnancy
The NHS says
If blood tests show your iron levels are low, your doctor or midwife may advise you to take an iron supplement (ferrous sulfate) in pregnancy. Iron supplements are safe to take while pregnant, and treating low iron is important to keep you and your baby healthy.
Constipation and piles (haemorrhoids) are common if you take iron supplements during pregnancy. A doctor, pharmacist or midwife can advise you on how to prevent them. If you do get constipation or piles, ask a doctor, midwife or pharmacist how best to treat them.
In our words, from the NHS page Ferrous sulfate (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
Ferrous sulfate while breastfeeding
The NHS says
Ferrous sulfate can usually be taken during breastfeeding.
Iron, including ferrous sulfate, is naturally found in breast milk. Taking an iron supplement does not change how much iron gets into your breast milk or reaches your baby.
So iron supplements are very unlikely to give your baby side effects.
However, if your baby's iron levels are also low, your baby will need their own treatment, because your supplements will not change their levels.
Contact your doctor, pharmacist, health visitor or midwife if your baby is feeding less well than normal, is constipated or has diarrhoea, or if anything else about your baby worries you.
In our words, from the NHS page Ferrous sulfate (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
LactMed says
Iron is a normal component in human milk. Daily oral iron intake from prenatal vitamins or other multimineral supplements does not affect milk iron levels. Higher daily oral iron dosing has a minimal effect on milk iron levels and is not expected to cause harm to the breastfed infant if needed to treat the mother’s anemia, but it is not an adequate substitute for direct infant iron supplementation to prevent or treat infant anemia.
“Summary of Use during Lactation”, LactMed record “Iron Salts” (iron_salts), quoted verbatim. Everything LactMed reports about Iron Salts while breastfeeding.
Other names
UK brand names (per the NHS): Ironorm Drops.
Sources
- NHS, Ferrous sulfate (nhs.uk), page last reviewed 9 February 2023. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Iron Salts” (iron_salts), bulk release of 22 September 2026. LactMed on NCBI Bookshelf. Public domain; quoted verbatim. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.