Nitrofurantoin Side Effects and Safety

Urinary tract infections (UTIs) such as cystitis are very common, uncomfortable and disruptive. To manage these, patients are often prescribed a short course of nitrofurantoin.

The main first-line treatment prescribed for UTIs in the UK is nitrofurantoin. Whilst very effective, any new medication can bring questions about safety and potential side effects.

Here, we’ll cover everything you need to know about using your treatment safely, minimising side effects of nitrofurantoin, and understanding how the treatment interacts with alcohol, pregnancy and breastfeeding.

Understanding Nitrofurantoin And How It Treats Cystitis

Nitrofurantoin is an antibiotic that's made specifically to treat infections in the urinary tract. Unlike other antibiotics which spread through the entire body, nitrofurantoin is filtered out of the blood and concentrates in urine.

Because of this, it attacks bacteria right at the source, leaving the rest of the body relatively undisturbed. This makes it a perfect choice for treating cystitis.

For more information on how bladder infections develop and are diagnosed, feel free to read our guide on cystitis and UTIs.

How Long Does Nitrofurantoin Take To Work On a UTI

When dealing with the painful burning and urgency of cystitis, a primary concern is to find something that works fast.

Nitrofurantoin starts fighting the infection within a few hours of taking the first dose. However, it usually takes 24 to 48 hours to notice a significant improvement, as it takes time to clear the bacteria and allow the bladder lining to heal.

Even if symptoms are completely clear after the first day, it’s important to complete the entire course of antibiotics. Stopping early can cause the infection to return more severe, and become resistant to antibiotics.

What Are The Common Side Effects Of Nitrofurantoin?

Most who are prescribed nitrofurantoin tolerate the treatment well. However, like all medications, it can cause side effects.

Mild And Common Side Effects

Most side effects are temporary and resolve on their own once the course is finished. The most frequent concerns are:

• Nausea and vomiting

• Loss of appetite and abdominal discomfort

• Diarrhoea

• Headaches

• Dizziness or drowsiness

How To Manage Common Side Effects

Why Does Nitrofurantoin Turn Urine Brown

A harmless but usually alarming side effect of nitrofurantoin is that it can change urine colour to dark yellow, amber or brown.

This occurs because of how the drug is broken down as it travels through the body and is completely harmless. It is a sign the drug is concentrated in the urine - exactly where it needs to be to fight the infection.

Your urine will return to its normal colour, as you complete the course.

Serious Side Effects Requiring Immediate Action

Whilst rare, serious side effects can occur. If you experience any of the following, you should stop taking the medication and seek immediate medical attention:

• Respiratory problems - such as a cough, breathing difficulties, shortness of breath or a persistent fever.

• Liver problems - yellowing of the eyes or skin, unusually dark urine with pale stools or severe abdominal pain.

• Neuropathy - tingling, numbness, pins and needles, or muscle weakness in the hands, arms, feet, or legs.

• Severe allergic reactions - including swelling of the face, lips, tongue or throat with difficulty breathing or swallowing and a sudden skin rash.

Nitrofurantoin Dosage for UTis: How Many Days

To clear the infection, nitrofurantoin must be taken at the right dose for the right duration. How long you take it for depends on your gender, medical history and the severity of your infection.

Uncomplicated Cystitis Treatment

For uncomplicated UTIs, nitrofurantoin is usually prescribed as 100mg, slow-release capsules, taken twice daily for 3 days.

In men, courses are generally 7-days, longer than for women, as UTIs in men are usually more complex.

Preventative Dosage

In cases where a patient suffers from chronic, recurrent UTIs, a GP may prescribe a lower dose of nitrofurantoin that's taken every day, long-term.

Can You Drink Alcohol While Taking Nitrofurantoin?

There is no dangerous interaction between alcohol and nitrofurantoin. Drinking alcohol will not stop the antibiotic from working and nor will it cause any nasty side effects.

However, clinicians generally advise to limit or completely avoid alcohol during the treatment course for a few important reasons:

• Alcohol can irritate the bladder, worsening UTI symptoms like burning, and urinary urgency.

• Alcohol is dehydrating. To effectively overcome a UTI, you need to drink plenty of water to flush the bacteria out. Dehydration slows this down, contributing to symptoms.

• Added side effects. If you’re already experiencing dizziness or headaches, because of the treatment, alcohol will likely worsen these.

If you do choose to have a drink, make sure you stick to UK recommended guidelines, keep intake minimal and have a large glass of water with every alcoholic drink.

Is Nitrofurantoin Safe In Pregnancy?

UTIs are very common during pregnancy, due to the hormonal and structural changes during this time.

Nitrofurantoin has safely been used to treat UTIs during pregnancy, but the timing matters:

• First and second trimesters - no increased risk of birth defects or harm to the baby.

• Third trimester (near term) - generally avoided, due to a small risk of haemolytic anaemia, affecting the baby’s blood.

If you are pregnant, or planning a family, always notify your prescriber to allow them to tailor your therapy safely to your stage of pregnancy.

For a deeper look at alternate treatment pathways, take a look at our guide comparing UTI and cystitis treatments. Breastfeeding And Nitrofurantoin Safety

If breastfeeding, you can safely take nitrofurantoin. Very small amounts of the antibiotic pass through breast milk into the baby, which is usually not enough to cause adverse effects in a healthy full-term infant.

However, you should exercise caution if the baby:

• Was born premature.

• Is less than 30 days old.

• Has a genetic condition called G6PD deficiency.

• Is suffering from infant jaundice.

In these cases, the baby is more vulnerable, and an alternate antibiotic may be selected for the mother. Ensure your healthcare provider knows you are breastfeeding before starting treatment.

Practical Tips For Taking Nitrofurantoin Safely

To ensure your treatment is as effective as possible, whilst minimising side effects, keep the following in mind:

• Take with or after food, to reduce nausea

• Space doses evenly - roughly 12 hours apart to maintain a steady concentration of antibiotic in your urine.

• Complete the full course. Even if your symptoms start to clear. Stopping an antibiotic course early allows some bacteria to survive, causing re-infection and antibiotic resistance.

• Adequate hydration, to help flush bacteria out.

• Do not share your antibiotics with anyone else.

Who should not take nitrofurantoin?

Whilst highly effective, nitrofurantoin is not suitable for everyone. It is usually avoided if you have:

• Severe kidney problems.

• A history of drug allergies.

• Have G6PD deficiency - a rare condition that affects your blood cells.

• Anaemia or vitamin B deficiency

• Porphyria - a rare blood disorder.

Where To Buy Nitrofurantoin

If you are experiencing cystitis, you can conveniently access treatment online.

Nitrofurantoin is available from Quick Meds, a GPhC-registered online pharmacy. Following a quick online consultation, our UK-based prescribers can verify your symptoms and if appropriate, issue a prescription, delivered discreetly straight to your door.