Ferrous sulfate

Ferrous sulfate (or sulphate) is a type of iron that's used as a medicine to treat and prevent iron deficiency anaemia.

Iron helps the body to make healthy red blood cells, which carry oxygen around the body. Some things such as blood loss, pregnancy or too little iron in your diet can make your iron supply drop too low, leading to anaemia.

Ferrous sulfate comes as tablets, or as drops that you swallow.

It is available on prescription and to buy from pharmacies.

Most adults and some children aged 12 years and over can take ferrous sulfate with the advice of a doctor or pharmacist.

Ferrous sulfate is not suitable for some people.

To make sure it's safe for you, tell your doctor before taking ferrous sulfate if you:

• have ever had an allergic reaction to ferrous sulfate or any other medicine
• have a different type of anaemia that is not caused by low levels of iron
• have any other conditions that affect your iron levels, such as haemochromatosis or haemosiderosis
• have a condition that affects your red blood cells, such as sickle cell anaemia or thalassaemia
• have a stomach ulcer, have had all or part of your stomach removed, or have other stomach or bowel problems such as inflammatory bowel disease
• are having repeated blood transfusions
• have noticed blood in your pee
• have been diagnosed with an iron deficiency and are already receiving treatment for this

Ferrous sulfate comes as 200mg tablets, or as drops containing 125mg of ferrous sulfate in 1ml.

Your dose of ferrous sulfate depends on why you're taking it and whether you take tablets or drops.

Dose to treat anaemia

The usual dose for adults is:

• tablets – one 200mg tablet usually once a day, but it may be 2 to 3 times a day. If you get side effects your doctor may advise you to take it on alternate days
• drops – 4ml, taken once or twice a day

For children aged 12 to 17 years, the doctor will use your child's age and blood results to work out the right dose of ferrous sulfate. For children under 12 years old, the doctor will also use your child's weight to work out the right dose.

Dose to prevent anaemia

The usual dose for adults is:

• tablets – one 200mg tablet, taken once a day
• drops – 2.4ml to 4.8ml, taken once a day

For children aged 12 to 17 years, the doctor will use your child's age and blood results to work out the right dose of ferrous sulfate. For children under 12 years, the doctor will also use your child's weight to work out the right dose.

Ferrous sulfate works best when you take it on an empty stomach. If you can, take it 30 minutes before eating, or 2 hours after eating. But if it upsets your stomach, you can take it with or after food.

A doctor (or a pharmacist) may recommend taking ferrous sulfate with orange juice or a vitamin C supplement. Vitamin C is believed to increase the amount of iron absorbed by the body.

Swallow the tablet whole with a drink of water. Do not suck, chew or keep the tablet in your mouth as this can cause mouth ulcers or stain your teeth.

Do not take it with tea, coffee, eggs or dairy products, as they can reduce the amount of iron that gets into your system. When you take ferrous sulfate (or when you eat foods that are high in iron), leave a 2-hour gap before having these foods or drinks.

If you have difficulty swallowing the tablets tell your doctor or pharmacist.

The drops may be easier for children and people who find it difficult to swallow tablets.

If you're taking ferrous sulfate as drops, it will come with a plastic syringe or dropper to help you measure out the right dose. If you do not have one, ask a pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount of medicine.

Keep ferrous sulfate out of sight and reach of children, as an overdose may be fatal.

Ferrous sulfate is not harmful if it's been prescribed for your child and you follow your doctor's instructions, or the instructions on the packet.

To prevent iron deficiency anaemia, you'll need to take ferrous sulfate for as long as you're at risk of getting this condition.

To treat iron deficiency anaemia, you'll need to take it for several months. Your doctor will usually advise you to keep taking it for 3 to 6 months after your condition has improved to help build up your body's iron supply.

If you forget a dose, take it as soon as you remember, unless it's almost time to take the next dose. In this case, skip the missed dose and take your next dose at the usual time.

Do not take 2 doses to make up for a forgotten dose.

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to remember to take your medicine.

Taking more than the recommended dose of ferrous sulfate can cause vomiting, stomach pain or diarrhoea.

In serious cases you may vomit blood, have a seizure or fit, or become unconscious.

• you or your child takes more than the recommended dose of ferrous sulfate

Go to 111.nhs.uk or call 111

If you need to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance.

Bring the ferrous sulfate packet or leaflet inside it, any remaining medicine, and any other medicines you take.

There are things you can do to cope with these common side effects of ferrous sulfate:

Try taking ferrous sulfate with, or just after, a meal or snack. Stick to simple meals and do not eat rich or spicy food. If you're being sick, try small frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.

If you take the combined contraceptive pill or the progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.

Try taking ferrous sulfate with, or just after, a meal or snack. It can help to eat and drink slowly and have smaller and more frequent meals.

Eat when you would usually expect to be hungry. If it helps, eat smaller meals more often than usual. Snack when you're hungry. Have nutritious snacks that are high in calories and protein, such as dried fruit and nuts.

To help with constipation, get more fibre into your diet by eating fresh fruit, vegetables and cereals, and drink plenty of water. Try to exercise more regularly, for example, by going for a daily walk or run.

Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.

If you take the combined contraceptive pill or the progestogen-only pill and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.

This is common when taking iron and is usually nothing to worry about.

Rinse your mouth with water after taking the drops. Do not suck or chew the tablet, or keep it in your mouth.

Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.

Talk to a doctor or call 111 straight away if your poo is black, tar-like or red, or has blood in or on it, or if you also feel unwell in any other way.

Serious allergic reaction

In rare cases it's possible to have a serious allergic reaction (anaphylaxis) to ferrous sulfate.

Call 999 now if:

• your lips, mouth, throat or tongue suddenly become swollen
• you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
• your throat feels tight or you're struggling to swallow
• your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
• you suddenly become very confused, drowsy or dizzy
• someone faints and cannot be woken up
• a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.

These can be signs of a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of ferrous sulfate. For a full list, see the leaflet inside your medicines packet.

Your doctor or midwife may recommend that you take an iron supplement (ferrous sulfate) in pregnancy if blood tests have shown that your iron levels are low. Iron supplements are safe to take in pregnancy and it's important that low iron levels are treated so that you and your baby stay healthy.

If you're pregnant and taking iron supplements, it's common to become constipated or get piles (haemorrhoids). A doctor, pharmacist or midwife can give you advice on how to avoid this. If you do get constipation or piles, talk to a doctor, midwife or pharmacist about the best way to treat this.

You can usually take ferrous sulfate while you are breastfeeding.

Iron (including ferrous sulfate) is a natural part of breast milk. When you take iron as a supplement it does not affect how much gets into breast milk or how much gets to your baby.

This means that taking iron supplements is very unlikely to cause any side effects in your baby.

However, if your baby also has low iron levels, they will need to be treated directly. Any iron supplements that you're taking will not affect their levels.

If you notice your baby is not feeding as well as usual, or has constipation or diarrhoea, or you have any other concerns about your baby, contact your doctor, pharmacist, health visitor or midwife.

There's no evidence that ferrous sulfate will affect fertility in either men or women.

Tell your doctor if you're:

• trying to get pregnant
• pregnant
• breastfeeding

There are some medicines that may affect how ferrous sulfate works. Ferrous sulfate can also affect the way other medicines work.

It's a good idea to leave a gap between taking ferrous sulfate and any other medicine. Ask a doctor or pharmacist for advice on how long the gap should be.

Tell a pharmacist or doctor if you're taking any of these medicines before you start taking ferrous sulfate:

• iron injections, or supplements containing iron, calcium, magnesium or zinc
• antacids or other indigestion remedies
• antibiotics such as oxytetracycline, doxycycline, ciprofloxacin or chloramphenicol
• antivirals used for HIV infection such as bictegravir or dolutegravir
• laxatives containing magnesium such as magnesium hydroxide or Milk of Magnesia
• medicines used to treat or prevent osteoporosis (bisphosphonates), such as alendronic acid or risedronate
• cholestyramine, a medicine used to reduce cholesterol and treat itching caused by liver disease
• eltrombopag, a medicine used to increase platelets in the blood
• levothyroxine, a medicine used to treat an underactive thyroid
• levodopa, carbidopa or entacapone, medicines used to treat Parkinson's disease
• mycophenolate, a medicine used after an organ transplant
• methyldopa, a medicine used to treat high blood pressure
• penicillamine, a medicine used to treat arthritis
• trientine, a medicine used to treat Wilson's disease

Talk to a pharmacist or doctor before taking any herbal remedies or supplements together with ferrous sulfate. Some vitamin and mineral supplements may already contain ferrous sulfate or other types of iron.

Tell the pharmacist or doctor if you take any supplements or remedies that contain iron, calcium, magnesium or zinc. Ferrous sulfate can stop zinc working as well as it should. Calcium can reduce the effect of ferrous sulfate.

Tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.