Ferrous sulfate

Ferrous sulfate is a supplement that treats iron deficiency anaemia, a condition where the number of red blood cells you have is lower than it needs to be.^[1]
This means your body doesn’t get enough oxygen-rich blood. There are several causes of anaemia, including folate and B12 deficiency, but iron deficiency is the most common one^[2]

Low levels of iron in your blood can be caused by multiple factors, including pregnancy, blood loss, or a diet that’s low in iron rich-foods. A blood test can usually determine if iron deficiency anaemia is causing your symptoms, which usually include tiredness, a pale complexion, shortness of breath and heartbeats that seem irregular, also known as palpitations.

Iron is a mineral that helps your body make red blood cells. There are lots of things that can cause low iron levels. Non-steroidal anti-inflammatory drugs (NSAIDs) can make your stomach and intestines bleed, as can bowel cancer and stomach ulcers. Bleeding in this way is one of the most common causes of iron deficiency anaemia in men and postmenopausal women.

For women who are of reproductive age, a lack of iron can be caused by heavy periods. Pregnancy is another reason your iron levels might be low, as your body needs more for your baby.^[1]

Ferrous sulfate works by increasing the iron in your blood. Boosting your iron levels means you can make more haemoglobin, a vital protein for red blood cells. Having healthy red blood cells means oxygen can travel from your lungs to different parts of your body.

What doses of Ferrous sulfate are there?

Ferrous sulfate is available as 200mg, film-coated tablets. For preventing anaemia, the usual dose is one tablet per day.

For treating low iron levels, people are advised to take 2 tablets, three times a day. Whether or not you’ll need this amount will depend on your iron levels at the start of your treatment. A clinician will usually ask to see a recent blood test, or diagnosis of iron deficiency from your GP, to decide the amount of Ferrous sulfate you’ll need.

Ferrous sulfate supplements work best when they’re taken on an empty stomach. You should try to take your tablet(s) half an hour before eating, or 2 hours after a meal. Swallow them whole with a glass of water.

Sometimes, clinicians suggest taking the tablets with a drink of orange juice, or alongside a Vitamin C supplement. Vitamin C is thought to help you absorb iron better. With that in mind, it’s best to avoid drinking coffee, tea, and certain dairy products, as these can inhibit the amount of iron you absorb.^[1]

Replenishing your iron stores often needs time and patience. You might start to feel better after 3-4 weeks of taking Ferrous sulfate daily, but people often need to use the supplements for longer than that before their iron levels are back to normal. This can take between 2-4 months, but it can depend on factors like how deficient you were to begin with, and how well you absorb Ferrous sulfate.

While you’re taking the supplements, a clinician might advise you to try and increase your dietary iron intake. This means eating iron-rich foods like red meat, nuts, fortified breakfast cereals and dark leafy greens. If you’re vegetarian or have a restrictive diet for any other reasons, it might be worth discussing your diet with them to see what you can do to improve the amount of iron you’re getting.

It’s important you stick to the dosage routine you’ve been recommended. Taking too much Ferrous sulfate at once can cause stomach pain, diarrhoea, and vomiting. In some cases, it can induce seizures.^[2]
If you miss a dose, take it as soon as you remember as long as it’s not too close to the time your next tablet is due. In this case, skip the one you missed and carry on as normal.

If you know you’ve taken more tablets than you need, head to your nearest casualty department. If you can, bring the box your medication arrived in, along with the patient information leaflet (PIL). This will help hospital staff get you the help you need faster.