Nitrofurantoin

What is nitrofurantoin?

Nitrofurantoin is a prescription-only antibiotic used primarily to treat and prevent urinary tract infections (UTIs). It works by killing bacteria that cause infections in the urinary tract. It is available under brand names such as Macrobid, Macrodantin, Furadantin, and Aratoin[1]. 

What is nitrofurantoin used for?

Nitrofurantoin is used to treat and prevent certain urinary infections. Specifically, it is prescribed to[1]: 

• Treat lower urinary tract infections (e.g., cystitis or bladder infections) 

• Prevent recurrent UTIs in people prone to them 

It is not suitable for treating kidney infections (upper UTIs) or infections outside the urinary tract due to its low tissue penetration. 

How does nitrofurantoin work?

Nitrofurantoin works by damaging bacterial DNA, ribosomal proteins, and other essential components within bacterial cells. This makes it bactericidal, meaning it effectively kills the bacteria. Because it concentrates in the urine, it is particularly effective for bladder infections[1]. 

Who can take nitrofurantoin?

Most adults and children over 3 months can take nitrofurantoin. However, it is not suitable for everyone. You should speak to your doctor first if you[1]: 

• Have severe kidney disease 

• Are pregnant, particularly in the third trimester 

• Have diabetes 

• Have a lung condition 

• Have any liver problems 

• Have any condition causing severe weakness 

• Have anaemia or vitamin b deficiency 

• Have G6PD deficiency or porphyria 

• Are allergic to nitrofurantoin or related compounds 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is the typical dosage of nitrofurantoin?

Nitrofurantoin tablets and capsules come as 50mg or 100mg strengths. The slow-release capsules are 100mg. The liquid comes as 25mg in 5ml. The dose of nitrofurantoin depends on your condition[1]: 

• Treatment of UTIs: Usually 50mg standard tablets 4 times a day or 100mg slow-release tablets 2 times a day  

• Prevention of UTIs: 50mg to 100mg standard tablets or capsules once daily at night 

Doses for children are weight-based and prescribed by a doctor. Always follow your pharmacist or doctor’s instructions or the label on your prescription. 

How do you take nitrofurantoin?

The way you take nitrofurantoin can help it work effectively and reduce side effects[1]: 

• Take with food or milk to improve absorption and reduce stomach upset 

• Swallow tablets or capsules whole with water 

• Space doses evenly throughout the day 

Can you stop taking nitrofurantoin?

No – unless advised to by your prescriber you should complete the full course, even if you feel better. Stopping early can lead to the infection returning and contribute to antibiotic resistance[1]. 

What do you do if you take too much nitrofurantoin?

Taking an extra dose of nitrofurantoin is unlikely to be harmful, however if you are worried, get severe side effects or have taken more than one extra dose contact 111, your pharmacist or prescriber for advice.  Symptoms of overdose may include[1]: 

• Nausea or vomiting 

• Dizziness 

• Neurological symptoms 

If you need to go to A&E do not drive. Ask someone to drive you or call for an ambulance if this is not possible. If you still have the packaging of your medication, take this with you. 

What do you do if you forget to take nitrofurantoin?

If you forget a dose[1]: 

• Take it as soon as you remember 

• If it’s nearly time for your next dose, skip the missed one 

• Do not double up to make up for a missed dose 

• Antibiotics are effective when taken consistently, and missing several doses may result in treatment failure 

How do I store nitrofurantoin?

To ensure the medicine stays effective[1]: 

• Store in a cool, dry place below 25°C 

• Keep out of sight and reach of children 

• Do not use after the expiry date on the packaging 

What medicines can’t you take with nitrofurantoin?

Certain medicines can interfere with how nitrofurantoin works or increase side effects. Avoid or use with caution[1]: 

• Antacids containing magnesium trisilicate (reduce absorption) 

• Cystitis remedies you can buy from a pharmacy 

• Quinolone antibiotics (e.g., ciprofloxacin – may interact) 

• Oral typhoid vaccine (effectiveness may be reduced) 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of nitrofurantoin?

Common side effects of nitrofurantoin include[1]: 

• Nausea 

• Vomiting 

• Headache 

• Loss of appetite 

• Diarrhoea 

• Dizziness or tiredness 

• Urine may turn dark yellow or brown (this is normal and not a reason to stop taking the medicine) 

Serious side effects occur in less than 1 in 1,000 people and include[1]: 

• Lung problems (shortness of breath, cough) 

• Liver problems (jaundice, dark urine) 

• Nerve damage (tingling, numbness) 

• Severe headaches 

• Blood problems (bruising, bleeding, nosebleeds) 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about nitrofurantoin

Can I drink alcohol while taking nitrofurantoin? 
Yes, you can drink alcohol while taking nitrofurantoin. It does not interact with the medicine[1]. 

Can I take nitrofurantoin during pregnancy? 
Yes, but it should not be used during labour or close to delivery. It is important to tell your prescriber if you are pregnant[1]. 

Is it safe while breastfeeding? 
Small amounts of nitrofurantoin can be found in breast milk, enough to cause complications if your infant has a C6PD deficiency. Speak to your prescriber if you are breastfeeding[1]. 

Does nitrofurantoin affect contraception? 
No, it does not interfere with hormonal contraceptives[1]. 

Can I drive while taking it? 
Yes, unless you experience dizziness or drowsiness[1]. 

Why has my urine changed colour? 
It’s a harmless side effect of the medicine[1]. 

Can I take it long-term? 
Yes, it may be used for prevention of UTIs but requires regular monitoring[1]. 

Is it safe for children? 
Yes, for children over 3 months old[1]. 

What if I have kidney problems? 
It may not be suitable. Your doctor will check your kidney function first[1]. 

For the official NHS guide to nitrofurantoin, visit their website.