Ferrous Fumarate

What is ferrous fumarate used to treat?

Ferrous fumarate is an iron supplement used to treat and prevent iron deficiency anaemia. Iron is essential for making haemoglobin – the protein in red blood cells that carries oxygen around your body[1]. 

It’s commonly prescribed to[1]: 

• Treat iron deficiency anaemia 

• Prevent anaemia in people at risk (such as during pregnancy, after significant blood loss, or with poor dietary iron intake) 

How does ferrous fumarate work?

Ferrous fumarate contains elemental iron, which your body absorbs in the small intestine. It helps by[1]: 

• Replenishing iron stores in the body 

• Supporting healthy red blood cell production 

• Improving oxygen transport throughout the body 

Who can take ferrous fumarate?

Most people can safely take ferrous fumarate. However, it’s not suitable for everyone. You should speak to your doctor if you[1]: 

• Have iron overload conditions (e.g., haemochromatosis) 

• Have a type of anaemia not caused by low iron (e.g., haemolytic anaemia) 

• Are allergic to ferrous fumarate 

• Have stomach ulcers or a history of gut problems 

• Have inflammatory bowel disease (like ulcerative colitis or Crohn’s) 

• Regularly receive blood transfusions 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is the typical dosage of ferrous fumarate?

Ferrous fumarate comes in tablet, capsule, and liquid form[1]: 

• Tablets come in 2 strengths: 210mg and 322mg 

• Capsules are 305mg 

• Liquid ferrous fumarate contains 140mg in each 5ml spoonful (140mg/5ml) 

Your dose depends on why you're taking it and whether you take tablets, capsules or liquid. 

If you’re taking tablets for anaemia, the usual dose is 210mg once a day, reduced to once every other day if needed, or 322mg once a day, reduced to 322mg once every other day if needed. If you’re taking capsules for anaemia, the usual dose is 305mg once a day, reduced to 305mg every other day if needed. If you’re taking the liquid solution, the usual dose is 5-10ml once a day, reduced to 5-10ml every other day if needed[3]. 

If you experience side effects, you may be advised to take your dose on alternative days by your doctor. Your exact dose may vary depending on the severity of your anaemia and your doctor’s advice.

How do you take ferrous fumarate?

You should take ferrous fumarate on an empty stomach, either 1 hour before or 2 hours after food). If it causes stomach upset, you can take it with food, but you should avoid taking it within 2 hours of having tea, coffee, dairy, eggs, or soy as these can all reduce iron absorption. Taking it with a source of vitamin C (like orange juice) can improve absorption[1]. 

Swallow the tablet whole with water. Do not crush or chew unless your doctor advises. If you’re taking the liquid form, use the plastic syringe or spoon that comes with it to measure the correct dose. If you do not have either, ask your pharmacist for one. Don’t use a kitchen teaspoon as it will not measure the right amount[1]. 

Can you stop taking ferrous fumarate?

Only stop taking ferrous fumarate if your doctor tells you to. Even after your symptoms improve, you may need to continue taking it for several months to fully restore your iron levels[1]. 

What do you do if you take too much ferrous fumarate?

Taking too much iron is dangerous – especially for children. It can cause illness and, in some cases, be life-threatening. If you (or someone else) takes too much, seek emergency medical attention immediately. 

Symptoms of overdose may include[1]: 

• Severe stomach pain 

• Vomiting (possibly with blood) 

• Diarrhoea 

• Drowsiness or confusion 

What do you do if you forget to take ferrous fumarate?

If you miss a dose and you take ferrous fumarate[1]: 

• Once a day – take it as soon as you remember, unless it's less than 12 hours until your next dose, then you should skip the missed dose 

What medicines can’t you take with ferrous fumarate?

Ferrous fumarate can interact with several medications. Take extra care with[1]: 

• Antacids (reduce iron absorption) 

• Iron injections 

• Antibiotics (such as oxytetracycline, doxycycline, or ciprofloxacin) 

• HIV antiviral medication 

• Laxatives containing magnesium 

• Cholestyramine for high cholesterol 

• Eltrombopag (blood platelet medicine) 

• Tetracycline or quinolone antibiotics 

• Parkinson’s disease medication 

• Mycophenolate (for post-organ transplant surgery) 

• Methyldopa (for high blood pressure) 

• Levothyroxine (thyroid medication) 

• Bisphosphonates (for osteoporosis) 

• Trientine (for Wilson’s disease) 

• Penicillamine (used for rheumatoid arthritis) 

If your doctor allows you to take any of the above with ferrous fumarate, you should still leave at least a 2-hour gap. 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2].

What are the side effects of ferrous fumarate?

The most common side effects include[1]: 

• Nausea or vomiting 

• Constipation or diarrhoea 

• Stomach discomfort or cramping 

• Loss of appetite 

• Blackened teeth (from the liquid only) 

• Dark stools (harmless) 

You should seek immediate medical help if you experience[1]: 

• Severe abdominal pain 

• Vomiting blood or blood in stools 

• Melena (tar-like consistency to your stool) 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about ferrous fumarate

Can I take ferrous fumarate during pregnancy? 

Yes, it’s commonly prescribed during pregnancy to prevent or treat anaemia. Always take it under medical supervision[1]. 

Can children take ferrous fumarate? 
Only if advised by a doctor. Accidental overdose in children can be fatal, so it must be stored safely and kept out of reach[1]. 

How long does ferrous fumarate take to work? 

You might start feeling better after a week, but it can take several weeks to fully correct iron deficiency[1]. 

Can I drink alcohol while taking it? 

Moderate alcohol is generally safe, but excessive drinking can worsen anaemia or irritate your stomach[1]. 

Do I need to avoid any food or drink while taking ferrous fumarate 

Drinks such as tea and coffee and some milk and dairy products – cheese, eggs, yoghurt – can stop your body from absorbing iron effectively. Leave a 2-hour gap between consuming any of these and taking ferrous fumarate[1].

For the official NHS guide to ferrous fumarate, visit their website.