Nitrofurantoin

What is nitrofurantoin?

Nitrofurantoin is an antibiotic that is used to treat and prevent infections of the urinary tract, such as bladder infections. It works by killing or stopping the growth of the bugs that cause the infection. In people who get urinary tract infections often, nitrofurantoin can be used to prevent infections.

In New Zealand nitrofurantoin comes as 50 mg and 100 mg tablets.

Dose

• The dose of nitrofurantoin will be different for different people. Your doctor will determine the correct dose for you, based on your condition. The following is a guide:
  • To treat mild urinary tract infections, the dose is usually 50 mg four times a day for 5 or 7 days.
  • To treat more severe urinary tract infections or infections that happen often, the dose is usually 100 mg four times a day for 7 days.  
  • To prevent  urinary tract infections, the dose is usually  one tablet (50 mg or 100 mg) each night. Your doctor will tell you how long to take it for.
• Always take your nitrofurantoin exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much nitrofurantoin to take, how often to take it, and any special instructions.

How to take nitrofurantoin

• Take each dose with food or milk. If taken on an empty stomach, it may cause stomach upset.
• Keep taking nitrofurantoin for as long as your doctor or pharmacist tells you to.
• Do not stop taking nitrofurantoin, even if you feel better after a few days, unless your doctor tells you to.
• If you have been taking nitrofurantoin for longer than 6 months, or develop a cough, check with your doctor if you should carry on taking it. Long-term use of nitrofurantoin can cause lung problems.
• If you forget to take nitrofurantoin, take it as soon as you remember, but if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
• It is best to take the antibiotic for the number of days your doctor has told you to. Do not stop taking it, even if you feel your infection has cleared up. Talk to your doctor first.

Precautions – before taking nitrofurantoin

• Do you have any problems with the way your kidney or liver works?
• Are you pregnant or breastfeeding? 
• Do you have any breathing problems?
• Do you have diabetes?
• Do you have problems where your nerves cause pain or numbness (called peripheral neuropathy)?
• Have you have been told you have one of the following rare inherited conditions: porphyria or glucose-6-phosphate dehydrogenase (G6PD) deficiency?

If so, it’s important that you tell your doctor before you start taking nitrofurantoin. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Possible side effects

Like all medicines nitrofurantoin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Problems with your lungs

Nitrofurantoin can cause lung problems (called pulmonary reactions). This may occur within the first month of treatment or after long-term use of nitrofurantoin (generally for 6 months or longer). 

Tell your doctor immediately or ring HealthLine 0800 611 116 if you develop symptoms of lung problems, such as:

• cough
• chest pain
• shortness of breath and trouble breathing
• joint or muscle pain, fever (high temperature), chills.  

Other side effects

Interactions

Nitrofurantoin may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting nitrofurantoin or before starting any new medicines.

Learn more

Nitrofurantoin New Zealand Formulary Patient Information 
Nifuran Medsafe Consumer Information Sheet

References

1. Nitrofurantoin New Zealand Formulary 
2. Nitrofurantoin - Not Suitable In Renal Impairment Medsafe Prescriber Update 36(4): 51-52, December 2015
3. Nitrofurantoin - Do the Benefits Outweigh the Risks Long-Term? Medsafe Prescriber Update 33(2): 17-18, June 2012
4. Nifuran Medsafe Datasheet