Nitrofurantoin

Nitrofurantoin is suitable for most adults and children, but always check before taking it.

Nitrofurantoin is not suitable for some people. For example, check with your doctor if you have problems with your liver or a lung condition.

Nitrofurantoin comes as capsules, tablets or a liquid that you take 1 to 4 times a day. Follow the instructions that come with your medicine.

Common side effects of nitrofurantoin include feeling or being sick. More serious side effects can happen in rare cases.

It can cause problems to take nitrofurantoin with some other medicines, such as antacid medicines, and certain antibiotics called quinolones.

Most adults and children can take nitrofurantoin.

Nitrofurantoin is not suitable for some people. To make sure it's safe for you, tell your doctor if you have:

• ever had an allergic reaction to nitrofurantoin or any other medicine
• porphyria, a rare blood disorder
• glucose-6-phosphate dehydrogenase (G6PD) deficiency, a rare condition that affects your red blood cells
• severe kidney disease
• diabetes
• a lung condition
• problems with your liver
• any condition causing severe weakness
• anaemia or vitamin B deficiency

The dose of nitrofurantoin you take depends on whether it's to treat or prevent a urinary tract infection, your age, and how bad the infection is.

Tablets and capsules contain either 50mg or 100mg of nitrofurantoin. The slow release capsules are 100mg. The liquid contains 25mg in 5ml.

The usual adult dose to treat a urinary tract infection is:

• 100mg, taken as slow release capsules, twice a day
• 50mg, taken as standard tablets or capsules, 4 times a day
• 100mg, taken as standard tablets or capsules, 4 times a day, for severe infections

The usual adult dose to prevent a urinary tract infection coming back is 50mg to 100mg, taken as standard tablets or capsules, once a day at night.

In adults, nitrofurantoin can be given as a single dose of 50mg or 100mg for the prevention of recurrent urinary tract infection following exposure to a trigger.

Doses are usually lower for children. Your child's doctor will work out the correct dose based on your child's weight or age.

Try to space your doses evenly throughout the day. If you're taking nitrofurantoin twice a day, leave 12 hours between each dose – for example, take it at 8am and 8pm.

If you're taking it 4 times a day, this will usually be first thing in the morning, at about midday, late in the afternoon, and at bedtime.

Swallow nitrofurantoin tablets or capsules whole . Do not chew or break them.

If you're taking liquid nitrofurantoin, the medicine will come with a syringe or spoon to help you take the right amount. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a teaspoon as this will not measure the right amount.

Take nitrofurantoin with or after a meal or snack. This helps your body absorb the medicine, as well as helping to prevent an upset stomach.

Like all medicines, nitrofurantoin can cause side effects, although not everyone gets them.

Nitrofurantoin may cause your pee to turn dark yellow or a brownish colour. This is normal and is not a reason to stop taking the medicine. Your pee will return to its usual colour once you stop taking nitrofurantoin.

There are things you can do to help cope with some of the common side effects of nitrofurantoin:

Taking nitrofurantoin with or after a meal or snack should help prevent this. It may also help if you avoid rich or spicy food.

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

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

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

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

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.

Make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Painkillers you can buy without a prescription, such as paracetamol and ibuprofen, are safe to take with nitrofurantoin. Speak to your doctor if these do not help or the headaches are severe or do not go away.

If nitrofurantoin makes you feel dizzy, stop what you're doing and sit or lie down until you feel better. Do not drive a car, ride a bike or operate machinery while you're feeling dizzy or sleepy.

Keep taking the medicine, but tell your doctor if the advice on how to cope does not help and the side effects bother you or do not go away.

Serious side effects are rare and happen in less than 1 in 1,000 people.

Tell a doctor or call 111 straight away if you have:

• a cough, are coughing up blood or mucus, have shortness of breath, pain when you breathe or a high temperature – these can be signs of lung problems
• pale poo and dark pee together, or the whites of your eyes turn yellow or your skin turns yellow (this may be less obvious on brown or black skin) – this can be a sign of liver or gallbladder problems
• bruising or bleeding you cannot explain (including nosebleeds), sore throat, a high temperature and feeling tired or generally unwell – these can be signs of blood problems
• severe headaches

• you get chest pain or have difficulty breathing – these can be signs of lung problems
• you get pins and needles, tingling sensations, numbness or weakness – these can be signs of nerve problems

Do not drive to A&E. Ask someone to drive you or call 999 and ask for an ambulance.

Bring all the medicines you take with you.

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

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 nitrofurantoin. For a full list, see the leaflet inside your medicine packet.

You can take nitrofurantoin during pregnancy. It's generally recommended to avoid it towards the end of pregnancy. There's a small chance it could cause problems with your baby's red blood cells.

Most babies will not have this problem, but your doctor may recommend a different antibiotic if you are more than 28 weeks pregnant.

If your baby is healthy, you can usually take nitrofurantoin while breastfeeding, but talk to your doctor or pharmacist first.

Nitrofurantoin passes into breast milk in small amounts and is unlikely to cause side effects in your baby. But it's best to take nitrofurantoin only for a short time. If you need to take it for longer than a few weeks, talk to your doctor or pharmacist. If you have an infection, or are at risk of infections coming back, it's important that this is treated.

Do not take nitrofurantoin while breastfeeding if your baby has:

• jaundice – signs include yellowing of the whites of the eyes and the skin (this may be less obvious on brown or black skin), dark pee and pale poo
• very high levels of a substance called bilirubin in their blood
• glucose-6-phosphate dehydrogenase (G6PD) deficiency, a rare condition that affects red blood cells

It's very rare for breastfed babies to have side effects from medicines you're taking. But it's important to keep monitoring your baby if you're taking any medicine while breastfeeding.

Contact your healthcare professional or call 111 as soon as possible if you notice that your baby:

• is not feeding as well as usual or putting on weight as you would expect
• is being sick (vomiting) or has diarrhoea
• has oral thrush (a fungal infection in their mouth)

If your baby has any symptoms that are not listed, or if you're worried about them, you can also call 111 or contact any healthcare professional.

There are some medicines that do not mix well with nitrofurantoin.

Tell your doctor if you're taking any other medicines before you start taking nitrofurantoin, including:

• indigestion remedies known as antacids, particularly those that contain magnesium
• cystitis remedies you can buy from a pharmacy
• antibiotics known as quinolones, including nalidixic acid, ciprofloxacin, levofloxacin, norfloxacin, ofloxacin and moxifloxacin

Typhoid vaccines given by mouth may not work properly if you're taking nitrofurantoin. It does not affect typhoid vaccines given by injection.

These are not all the medicines that may cause problems if you take them with nitrofurantoin. For a full list, see the leaflet inside your medicine packet