Nitrofurantoin 100mg MR Tablets

  • Commonly used to treat Urinary Tract Infections (UTI)
  • Symptoms should improve within 3 days
  • Works by slowing the growth of bacteria in the body

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Nitrofurantoin (Macrobid) 100mg MR tablets for Cystitis

Cystitis is a type of Urinary Tract Infection (UTI) which is caused by an infection in the bladder. It can cause painful and uncomfortable symptoms such as pain or burning when going to the toilet. For most people cystitis will typically clear within a few days without the need of medication. However, for others, cystitis can come and go more frequently and may need medicine to help with recurring infections.

Nitrofurantoin tablets are an effective treatment for Cystitis and can clear the infection within just three days. You can buy Nitrofurantoin 100mg MR Tablets online at Medicine Direct following a consultation with one of our UK prescribers.

What is Nitrofurantoin?

Nitrofurantoin is an antibiotic which is very effective in slowing the growth of bacteria in the body.

It is commonly sold under the brand name Macrobid.

It comes in the form of capsules or tablets that you swallow, or a liquid you drink.

Nitrofurantoin is widely prescribed to treat urinary tract infections (UTIs) like kidney infections and cystitis. It can be taken by adults and children over 3 months old, although the dosage will differ for children.

You need a prescription to buy Nitrofurantoin tablets.

What is Nitrofurantoin used to treat?

Nitrofurantoin is mostly used to treat urinary tract infections (UTIs), more commonly known as cystitis.

When you take Nitrofurantoin, your body will filter it out of your blood and into your urine very swiftly, meaning the medicine is concentrated on the area of infection, making it an ideal treatment for urine infections.

You will normally be instructed to take it for between 3 and 7 days, depending on your individual problem.

What is cystitis?

Cystitis occurs when your bladder becomes inflamed, which is usually the result of a bladder infection. It is a very common type of UTI in women and, although not normally serious, it can be very uncomfortable. Cystitis can be mild and go away on its own after a few days, but sometimes it can flare-up frequently and require treatment with an antibiotic like Nitrofurantoin.

If left untreated, cystitis can cause kidney infections.

You may be suffering from cystitis if you have any of these symptoms:

  • Dark, cloudy or strong-smelling urine
  • Pain, stinging or burning when you urinate
  • Feeling sick, tired or unwell
  • Needing to urinate very frequently
  • Lower abdominal pain

How does Nitrofurantoin work?

Nitrofurantoin is an antibiotic medicine which enters the cells of the harmful bacteria and damages their genetic material. This kills the bacteria that causes the infection.

Taken orally, Nitrofurantoin is mostly filtered out of your blood and into your urine, which means it is able to focus solely on killing the bacteria that is causing the UTI.

Nitrofurantoin dose

Take Nitrofurantoin in the dose your doctor has prescribed for you. This dose will depend on the infection you are taking the medicine for.

The normal doses can be seen below:



To treat infections

One 50mg capsule or one 100mg capsule four times a day for seven days.

To prevent infections

One 50mg capsule or one 100mg capsule at bedtime

To prevent infections during surgery

One 50mg capsule four times a day on the day of the operation and for the next three days


If this medicine is prescribed for a child, the dose will be decided upon by their doctor and based on their weight.

Nitrofurantoin must not be taken by children under 3 months old.

How to take Nitrofurantoin

Take Nitrofurantoin capsules with food or milk. This will make the medicine more effective.

Swallow the capsules whole, do not crush, open or chew them.

To treat urinary tract infections, you will normally be instructed to take it for between three and seven days.

Always read the patient information leaflet for full instructions.

Are there any side effects?

Not everyone will experience side effects when taking this medicine, but there are common adverse reactions you should take note of.

If you suffer any of the below effects, you should keep taking the medicine but speak to your doctor if they persist:

  • Loss of appetite
  • Headaches
  • Feeling sick
  • Being sick or suffering diarrhoea
  • Dizziness or feeling drowsy

Please note, this is not an exhaustive list of the possible side effects. You may experience more severe adverse reactions, which can be found under the Side Effects tab on this page.

You should make sure you always read the leaflet which will accompany your Nitrofurantoin tablets.

Who can take Nitrofurantoin?

While it is generally considered to be a very safe antibiotic, Nitrofurantoin may not be suitable for everyone. You should consult your doctor or pharmacist before you use this medicine to treat cystitis or any other infections if any of the below apply to you:

  • You have severe kidney disease
  • You have diabetes
  • You have any illnesses which cause severe weakness
  • You have anaemia
  • You have vitamin B deficiency
  • You have had an allergic reaction to Nitrofurantoin or any other medication in the past
  • You have any of these rare inherited conditions: porphyria or glucose-6-phosphate dehydrogenase (G6PD) deficiency

Nitrofurantoin can be used by children when prescribed for them. However, it is not suitable for children under the age of 3 months.

This list may not be exhaustive. Before you start to take Nitrofurantoin, consult the patient information leaflet for a full list of precautions.

Can you buy Nitrofurantoin over the counter?

Nitrofurantoin is classed as a prescription-only medicine (POM), so it must be prescribed for you by a doctor.

Can you buy Nitrofurantoin online in the UK?

Yes, you can buy Nitrofurantoin online from registered pharmacies, such as Medicine Direct. To make sure you only receive genuine and safe medication, you should only ever order it from regulated pharmacies like ours.

Nitrofurantoin requires a prescription to be purchased, so before you can complete your order, you will need to have an online consultation to make sure it is safe for you. When you have answered some questions about your condition and medical history, one of our prescribers will assess your answers to ensure Nitrofurantoin is a suitable treatment.

Nitrofurantoin alternatives

Trimethoprim is another effective antibiotic medication available to order from Medicine Direct. This medicine works to stop the bacteria that causes UTIs from being able to reproduce, making it easier for your immune system to fight the infection effectively.

View our full range of treatments by visiting the Cystitis treatment page.

Nitrofurantoin Indications and Dose

All our doctors and pharmacists follow NICE guidelines when prescribing Nitrofurantoin.

Always take Nitrofurantoin (Macrobid) tablets exactly as instructed by your doctor. Read the patient information leaflet thoroughly before taking any course of antibiotics; speak to the doctor or pharmacy if you are unsure of how to take it.

How should I take it?

Nitrofurantoin tablets and capsules should be swallowed whole with a drink of water or milk. Do not chew or break Nitrofurantoin tablets or capsules.

What if I forget to take it?

If you miss a dose, take Nitrofurantoin as soon as you remember, as long as it is not almost time for your next scheduled dose. If it is almost time to take your next dose, just skip the dose you missed and continue to take it as normal.

Never take an extra dose of medicine to try and make up for missing a previous dose. Never take two doses at the same time.

To properly treat your cystitis, it is very important that you are consistent with taking your medication, which means you should not miss a dose. To make sure you remember to take Nitrofurantoin, try to take it at the same time every day. Some people find that setting an alarm to remind them can be useful.

What if I take more than I am supposed to?

Taking an extra dose of Nitrofurantoin is unlikely to cause you any harm.

However, speak to your doctor or pharmacy if you have taken more than one extra dose or are experiencing severe reactions as a result of taking too much.

How long do I need to take it for?

To treat a urinary tract infection, you will normally be required to use Nitrofurantoin for between 3 and 7 days.

To prevent a UTI like cystitis before having surgery, it is likely you will need to take it on the day you have the operation, and for the following three days.

To stop a UTI like cystitis from coming back, you may be instructed to take it for several months.

How long does it take to work?

You should start to feel better after a few days of taking Nitrofurantoin. Do not stop taking Nitrofurantoin until you have completed the treatment course prescribed by your doctor, even if you feel better. This will provide the most effective treatment.

Can I drink alcohol while taking Nitrofurantoin?

It is safe to drink alcohol in moderate amounts while taking Nitrofurantoin.

What should I do if it doesn’t work?

If Nitrofurantoin has not improved your symptoms after three days, tell your doctor. They should also know if you feel worse while taking it.

Will it affect my contraception?

No, Nitrofurantoin does not impact any type of contraception. If you vomit or have diarrhoea after taking Nitrofurantoin, this may reduce the effectiveness of your contraception. If this happens, read the information that comes with your contraception for guidance on what to do.

Is taking Nitrofurantoin for three days enough?

This depends on why you need to take it. Most people are prescribed Nitrofurantoin for between 3 and 7 days. Always take Nitrofurantoin for as long as your doctor has told you to. Do not stop taking it early, even if you feel better.

Can you prevent UTIs by drinking cranberry juice?

Drinking cranberry juice is not likely to treat or prevent urinary tract infections from occurring.

Can I make any lifestyle changes to prevent UTIs?

There are certain actions you can take and things you can avoid which will lessen the risk of getting a urinary tract infection. A full list of preventative measures can be found on the NHS’s website.

Can I get thrush from taking Nitrofurantoin?

Thrush is a possible side effect while taking an antibiotic medicine like Nitrofurantoin. This is because antibiotics will also kill the good bacteria that stops thrush from developing, leaving you vulnerable to this problem. If you get any thrush symptoms, speak to your doctor.

How long does Nitrofurantoin stay in your system?

Nitrofurantoin has an elimination half-life of around 30 minutes. It is normally excreted through your urine after around 4-5 hours of being taken. This antibiotic is quickly filtered into your urine, allowing it to get to work very quickly.

Does Nitrofurantoin affect fertility?

No hard evidence exists to suggest that Nitrofurantoin has any effect on male or female fertility. However, if you are pregnant or trying to get pregnant, you should tell your doctor before you start taking it.

Nitrofurantoin Side Effects

The list of common adverse reactions to this medication can be found on the main page for the product.

In rarer cases, you may experience more serious side effects than those listed on the main page.

You should seek medical attention immediately if you experience any of these reactions while taking Nitrofurantoin:

  • Severe headaches
  • Numbness or weakness, tingling sensations in your body or pins and needles - these could be the sign of a nerve problem
  • Pains in your chest, coughing or difficulty breathing
  • Chills or a high temperature (higher than 38C)
  • Pale stools and dark yellow or brown urine, yellow skin or the whites of your eyes turning yellow - these symptoms could be the sign of gallbladder or liver problems
  • Unexplained bruising or bleeding (including nosebleeds), a sore throat, feeling tired or generally unwell, a temperature above 38C - any of these symptoms could be a sign of blood problems

In some cases, you may experience a severe allergic reaction (anaphylaxis) and could require urgent treatment in hospital.

You should call 999 or go to A&E immediately if you experience any of these:

  • You are wheezing
  • You find it difficult to breathe or speak
  • You get a skin rash that may be itchy, blistered, peeling, swollen or red
  • You have tightness in the chest or throat
  • You mouth, lips, tongue, face or throat is swelling

This list may not be exhaustive. You should always make sure you read the patient information leaflet, which will accompany your medicine for the complete list of side effects you may suffer from when using this antibiotic.

Nitrofurantoin Warnings and drug interactions

Nitrofurantoin may interact with other medicines you are taking, whether these are prescription or non-prescription drugs you obtained from a pharmacy.

Whether you are taking Nitrofurantoin to treat cystitis or another type of infection, you should inform your doctor and pharmacy if you are currently taking any of the below medicines:

  • Cystitis remedies you can purchase online or from a pharmacy such as Trimethoprim
  • Antibiotics called quinolones, such as nalidixic acid, ciprofloxacin, levofloxacin, norfloxacin, ofloxacin and moxifloxacin
  • Metronidazole 400mg tablets to treat Bacterial Vaginosis as taking both at the same time increases the risk of peripheral neuropathy
  • Indigestion remedies (antacids), particularly ones which contain magnesium
  • Certain medicines used to treat gout, including probenecid or sulfinpyrazone

There is no evidence to show that you will have any trouble combining Nitrofurantoin with herbal remedies. However, if you are taking any herbal remedies, vitamins or supplements, it is always best to discuss them with your doctor before you take any prescription medicine.

If you have any doubts or concerns at all, you should speak to your doctor or pharmacist before you use this antibiotic.

Drinking alcohol while taking Nitrofurantoin will not interact with the medication.

Pregnancy and Breastfeeding Warning

If you are currently pregnant, trying to get pregnant or are breastfeeding, it is normally safe for you to use Nitrofurantoin. This medication goes straight into your urine, meaning that very little of it will pass through to the unborn baby.

It may not be suitable for all breastfed babies. Speak to your doctor before taking Nitrofurantoin if you are breastfeeding; this is especially important if your baby has a rare condition called glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Do not take this medicine in the final stages of pregnancy, or during labour and childbirth, as this may affect the baby's blood.

For more information on taking Nitrofurantoin during pregnancy, we recommend visiting BUMPS.

Nitrofurantoin Ingredients

The main active ingredient within this medicine is: Nitrofurantoin

For a full list of the inactive ingredients, please read the Summary of Product Characteristics

Delivery Company Delivery Service Price Details
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Order Friday by 2pm (subject to Dr approval)

Please note that next day delivery to Northern Ireland, Scottish Highlands & Islands and British Isles cannot be guaranteed. Please contact our team for more information.

Written byHussain Abdeh MPharm: 2211840

Published on: 12/10/2020

Updated on: 03/06/2021

This content has been written by our Superintendent Pharmacist Hussain Abdeh and has been medically reviewed by our Pharmacist Sonia Khan

Hussain Abdeh Superintendent Pharmacist at Medicine Direct

Hussain Abdeh
MPharm: 2211840

Pharmacist Independent Prescriber

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