Take nitrofurantoin with (or just after) a meal or a snack. This will help your body to absorb the medicine and help to prevent stomach upset.
Space out your doses evenly throughout the day, and remember to finish the course prescribed.
Nitrofurantoin can darken the colour of your urine. This is nothing to worry about.
|Type of medicine||An antibacterial|
|Used for||Urinary tract infection (UTI) in adults and in children over 3 months of age|
|Also called||Macrobid®; Genfura®|
|Available as||Tablets, capsules, prolonged-release capsules, oral liquid medicine|
A urine infection is often called a urinary tract infection (or simply, UTI) by doctors. Most urine infections are caused by germs (bacteria) that come from your own bowel. They are usually easily treated with a short course of an antibacterial medicine such as nitrofurantoin. Occasionally, longer-term treatment is needed to prevent infections from coming back. Nitrofurantoin works by killing the bacteria causing the infection.
Before taking nitrofurantoin
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking nitrofurantoin it is important that your doctor knows:
- If you are pregnant or breastfeeding. Although nitrofurantoin can be taken during pregnancy, it is still important that you tell your doctor about being pregnant.
- If you have any problems with the way your liver works, or if you have any problems with the way your kidneys work.
- If you have sugar diabetes (diabetes mellitus).
- If you have been told you have anaemia, or if you have low levels of vitamin B or folic acid.
- If you have any breathing problems.
- If you have a problem where your nerves cause pain or numbness, called peripheral neuropathy.
- If you have been told you have one of the following rare inherited conditions: porphyria or glucose-6-phosphate dehydrogenase (G6PD) deficiency.
- If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine.
How to take nitrofurantoin
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about nitrofurantoin, and will also provide you with a full list of the side-effects which you could experience from taking it.
- Take nitrofurantoin tablets/capsules exactly as your doctor tells you to. Your dose will depend upon whether you are being treated because you have an infection, or to prevent an infection from coming back. The directions for taking your doses will be printed on the label of the pack of tablets/capsules to remind you about what the doctor said to you.
- Take each of your doses with a snack or after eating a meal. Space them out evenly throughout the day - this means that tablets/capsules prescribed four times a day should ideally be taken every six hours, those prescribed twice a day should be taken every 12 hours, and those prescribed once a day should be taken every 24 hours.
- Keep taking the tablets/capsules until the course is finished. It is important you do this even if you feel well, otherwise your infection may come back. Most people taking nitrofurantoin are prescribed a short course of treatment which usually lasts between 3-7 days. If you have had several urine infections in a short period of time, your doctor will prescribe a longer course of treatment for you, often for six months.
- If you forget to take a dose at your usual time, take it as soon as you remember. Try to take the correct number of doses each day but do not take two doses at the same time to make up for a missed dose.
Getting the most from your treatment
- Most people improve within a few days of starting treatment. If your symptoms do not improve despite taking nitrofurantoin, go back to see your doctor, as you may need an alternative antibiotic. This is because some bacteria are resistant to some types of antibiotics.
- Nitrofurantoin can turn your urine a yellow/brown colour. This is quite harmless.
- If you buy any medicines, check with a pharmacist that they are suitable for you to take with nitrofurantoin. Some antacids can interfere with nitrofurantoin and stop it from working properly.
- If you are taking the contraceptive 'pill' at the same time as this antibiotic, the effectiveness of the 'pill' can be reduced if you have a bout of sickness (vomiting) or diarrhoea which lasts for more than 24 hours. If this should happen, ask your doctor or pharmacist for advice about what additional contraceptive precautions to use over the following few days. There is no need to use additional precautions for any bouts of sickness or diarrhoea which last for less than 24 hours.
- If you are due to have any medical or dental treatment, tell the person carrying out the treatment that you are taking nitrofurantoin. This is because it can affect the results of some diagnostic tests.
- Nitrofurantoin can stop the oral typhoid vaccine from working. If you are due to have any vaccinations while you are taking nitrofurantoin, please make sure the person treating you knows that you are taking it.
Can nitrofurantoin cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with nitrofurantoin. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Nitrofurantoin side-effects||What can I do if I experience this?|
|Feeling sick (nausea) or being sick (vomiting), loss of appetite||Stick to simple foods - avoid fatty or spicy meals. Remember to take nitrofurantoin with food|
|Diarrhoea||Drink plenty of water to replace lost fluids|
|Feeling dizzy or sleepy||Do not drive and do not use tools or machines while affected|
|Itchy rash, allergic-type reactions, swollen salivary glands||Speak with your doctor or a pharmacist for further advice|
Important: your doctor will have discussed with you the possibility of a less common side-effect that may affect your lungs. You should let your doctor know straightaway if you experience any of the following:
- Any difficulty breathing, pains in your chest, coughing, chills, or a high temperature (fever).
If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.
How to store nitrofurantoin
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL; MacroBID® Capsules 100 mg, ADVANZ Pharma (formerly Amdipharm Mercury Company Limited), The electronic Medicines Compendium. Dated February 2019.
Manufacturer's PIL, Nitrofurantoin 50 mg and 100 mg Capsules; ADVANZ Pharma (formerly Amdipharm Mercury Company Limited), The electronic Medicines Compendium. Dated October 2018.
Manufacturer's PIL, Nitrofurantoin 25 mg/5 ml Oral Suspension; ADVANZ Pharma, The electronic Medicines Compendium. Dated February 2019.
British National Formulary, 77th Edition (Mar 2019); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.