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  • Pack of Nitrofurantoin Mercury Pharma 100mg prolonged-release capsules
5 Our patients rate this 5 review
100mg (prolonged release)
6 Capsules (£14.99)

Prices include next-day delivery and prescription

6 Capsules £14.99

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Please note, this treatment is currently only available from OnlineClininic for women. If you are a man and showing symptoms of a urinary tract infection (UTI), you should visit your GP or GUM clinic. They will be able to rule out more serious underlying causes.

What is Nitrofurantoin?

Nitrofurantoin is an antibiotic. It is used to treat kidney and urinary tract infections. It is particularly effective due to the concentration of the medication in the urine after ingestion (however, this makes it less effective for fighting infections in other areas of the body).

Nitrofurantoin is the active ingredient and the generic name of the medication. It is also available elsewhere as a branded treatment, Macrobid. However, it should be noted, the generic and the branded versions are identical in contents and effects.

How does Nitrofurantoin work?

Nitrofurantoin is an effective treatment for cystitis (inflammation of the bladder) which is caused by a bacterial infection. As an antibiotic, it kills and slows the growth of the bacteria that are causing the infection. This allows your immune system to fight back and clear the infection.

This treatment is particularly good for bacterial UTIs, as once you have ingested a tablet, your body will filter it into your urine. This means the concentration of the active ingredient is higher, helping you to fight bacteria in areas of the body where urine passes. For this reason, Nitrofurantoin is the first-line treatment for cystitis.

Dosage instructions

As with all antibiotics, you must complete the entire course of this treatment to ensure the infection has completely cleared.

For women:

One 100mg MR tablet should be taken orally, twice daily, for three days. Doses should be taken in the morning and the evening. Doses should be taken with a meal or milk. This is to help the body absorb the tablet, and should also reduce side effects (such as nausea).

If symptoms persist beyond 3 days, you can continue to take the medication until they are alleviated, for up to 7 days.

If you find symptoms persist after 7 days, please seek immediate medical advice.

For men:

UTIs are less common infections for men. They are also considered more complicated due to an increased likelihood of there being a serious underlying medical condition. Men should take 100 mg of Nitrofurantoin twice daily, for 7 days.

Alternatively, take 50mg of Nitrofurantoin 4 times daily, for 7 days.

If you find symptoms persist after 7 days, please seek immediate medical advice.

Side effects

The most common side effect of this medication is nausea. The chance of this occurring can be reduced if the doses are taken with meals. Nitrofurantoin can also turn urine a dark yellow or brown colour. This is completely normal and will resolve itself once the course has been completed.

Other common side effects include (but are not limited to):

  • Vomiting
  • Loss of appetite
  • Stomach pain
  • Diarrhoea
  • Headache

Rare side effects may include:

  • Lung inflammation
  • Liver problems
  • Nerve damage
  • Hemolysis (red blood cell damage)

Please note, this is by no means a complete list of side effects, and in any case of feeling seriously unwell, you should seek immediate medical attention.


Patients with heavily compromised renal function should not be treated with Nitrofurantoin as it will not work for them. The same applies to patients with porphyria or G6PD deficiency.

Nitrofurantoin is generally well-tolerated, however you should consult with a doctor and exercise caution if you suffer from any of the following:

  • Diabetes
  • Anaemia
  • history of allergic reactions
  • kidney problems

Pregnancy and breastfeeding

Nitrofurantoin should not be taken shortly before giving birth due to the risk of it affecting the infant during labour or delivery.

Please consult with your doctor before using Nitrofurantoin when breastfeeding.


You should also inform your doctor of any medications you are taking. Equally, you should complete our consultation thoroughly and honestly. Certain treatments are known to interact negatively with Nitrofurantoin, for example:

  • Antigout preparations, e.g. sulfinpyrazone, probenecid
  • Glaucoma medication, e.g. acetazolamide
  • Quinolone antibiotics, e.g. nalidixic acid
  • Typhoid vaccine


Alcohol should be avoided when using this treatment as it may increase the chance of side effects occurring.

Alcohol causes dehydration, which in turn affects the ability of the body to fight the infection. This is because bacteria cannot be as easily flushed from the urinary tract.

It is advised to drink plenty of water to help treat UTIs.

Ordering online

To purchase this treatment in the UK, you are required to have a prescription. Our service provides a prescription, assuming our doctors approve the medication for your use. You must first complete a confidential consultation. We will then ship your order with next-day delivery to a work or home address. All orders are packaged discreetly.

Note: Decisions about treatment are for both the prescriber and the person to jointly consider during the consultation. However, the final decision will always be the prescriber’s.

Nitrofurantoin information
Product name Nitrofurantoin
Active ingredient(s) Nitrofurantoin
Manufacturer Various
Lowest price£14.99
Trustpilot rating 5/5
Trustpilot reviews 8
Availability In stock
Description An antibiotic and first-line treatment for cystitis
Exemption Subject to medical prescription
Administration Oral
Presentation Tablets
Available dosage100mg twice daily for 3 days
Application Women over 18 with cystitis
Posology Consult patient leaflet
Drug classAntibiotics
Alcohol consumption In moderation
When pregnant/breastfeeding In some cases, consult your doctor
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Service ratings
Rating Excellent 4.9 2,189 patients have rated our service
Product ratings
Excellent 5 8 patients have reviewed Nitrofurantoin
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Current reviews for the treatment Nitrofurantoin

Rated with 5 based on 8 Independent customer reviews.

  • Excellent Product Review: Antibiotics working well 19 Dec
  • Excellent Product Review: This service is excellent. It’s fast and reliable. 12 Dec
  • Excellent Product Review: Very important and much needed antibiotic for conditions like cystitis . A quest... 21 Oct
  • Excellent Product Review: Straight forward ordering and express delivery service 14 Jun
  • Excellent Product Review: Very efficient with the order and delivery. 09 Apr