Nitrofurantoin

What is Nitrofurantoin?

Nitrofurantoin is an antibiotic used to treat uncomplicated urinary tract infections (UTIs). An uncomplicated UTI may involve the bladder but does not involve the kidneys. UTIs are usually caused by bacteria travelling up the urethra and into the bladder.

How does Nitrofurantoin work?

Nitrofurantoin works by concentrating in the bladder, killing bacteria which have entered the bladder through the urethra and multiplied. At lower concentrations nitrofurantoin is generally bacteriostatic, meaning it stops bacteria from reproducing, At higher concentrations Nitrofurantoin is bactericidal, meaning it kills bacteria.

How long does it take for Nitrofurantoin to work?

Nitrofurantoin takes effect within days to stop bacteria from multiplying. For uncomplicated urinary tract infections, a 3 to 7 day course may be prescribed. Nitrofurantoin can also be used to prevent UTIs in patients with recurrent infections.  Used for prevention, it may be prescribed daily for several months. Ultimately, your doctor will decide the appropriate duration of treatment.

Does Nitrofurantoin treat kidney infections?

Nitrofurantoin is not appropriate for treatment of kidney infections. Although it may have some effect, your doctor is likely to prescribe an alternative, better suited antibiotic for this purpose. 

Active ingredients

Each capsule contains 50 or 100mg of Nitrofurantoin as the active ingredient. 

Inactive ingredients

Additional ingredients include lactose, maize starch, pregelatinised maize starch, sodium starch glycolate, magnesium stearate. Inactive ingredients may vary between manufacturers.

How to take Nitrofurantoin

To treat a UTI you'll usually take 200mg of Nitrofurantoin each day. This might be in the format of 2-4 pills daily. Space these out evenly throughout the day; taking one in the morning and one 12 hours later in the evening. If the dose is split into 4 tablets then you should take these every 3-4 hours. Always take the full course of antibiotics as prescribed. 

When should you start taking Nitrofurantoin?

Nitrofurantoin should be taken as soon as possible after noticing symptoms. 

Do I need to finish a course of Nitrofurantoin even when my symptoms have resolved?

Always finish the course of Nitrofurantoin that you have been prescribed. Stopping treatment early can lead to a recurrence of the infection, as bacteria may still be present in the bladder. 

What if I take too many Nitrofurantoin tablets?

Accidentally taking one additional dose of Nitrofurantoin should not result in significant toxicity.  If you take more than one additional dose, you should contact your doctor or seek medical attention.

Nitrofurantoin side effects

Side Effects commonly include: 

• Drowsiness 

• Nausea 

• Diarrhea 

• Abdominal pain 

• Vomiting 

• Reduced appetite 

• Feeling dizzy 

• Headache 

• Darker urine 

Serious side effects which require attention from a doctor include: 

• Weakness, numbness or tingling in the muscles or joints 

• Yellowed skin (jaundice) 

• Coughing, chest pain and shortness of breath 

• Fever or chills 

• Unexplained bruising or bleeding 

• A severe headache  

• Allergic reaction

• Feeling generally unwell

Contraindications

Tell your doctor if you have any of the following conditions: 

• A history of allergic reactions to any of the ingredients in nitrofurantoin or to similar medicines 
• Porphyria
• Glucose-6-phosphate dehydrogenase deficiency (favism)
• Diabetes 
• Severe kidney disease 
• Anemia 
• Vitamin B12 deficiency
• Severe weakness due to an unrelated medical condition 

Regarding the above conditions, your doctor will be able to assess if nitrofurantoin is suitable for you. 

Drug interactions

Certain medications may interact with Nitrofurantoin. Tell your doctor if you are taking: 

• Antacids 

• Medication for gout 

• Any over-the-counter UTI remedies 

• Quinolones

How to avoid UTIs

A UTI can be uncomfortable, painful and disruptive to your daily life. If you are prone to UTIs, you can try to implement these preventative steps:

• Drink lots of water

• Wipe from front to back after going to the toilet

• Always urinate after sexual intercourse 

• Avoid using contraception with spermicide 

• Avoid perfumed washes and perfumed sanitary products

Macrobid vs Nitrofurantoin

Macrobid and Nitrofurantoin are the same medication with the same active ingredient. Nitrofurantoin is the generic name for the medicine while Macrobid is a brand name. 

Alternatives to Nitrofurantoin

Some alternative antibiotics for a UTI include: 

• Cephalexin 

• Fosfomycin 

• Ceftriaxone 

• Trimethoprim

Cranberry juice and Nitrofurantoin

Cranberry juice is often marketed as being helpful for preventing urinary tract infections.  Although some studies have shown that cranberry juice helps in this regard, to date, there is no definitive evidence to support this claim.  Cranberry juice does not help treat active infection.