Macrobid S/R
  • Macrobid S/R


Medication features

  • Twice daily dosage
  • Three-day course
  • For bacterial infections in the urinary tract (UTIs/Cystitis)
  • Generic Macrobid Nitrofurantoin available for £11.99


Macrobid 100mg Online in the UK

You can request to buy Macrobid for UTIs (urinary tract infections) online from Simple Online Pharmacy. Our UK registered online doctor and pharmacy service can provide Macrobid capsules, if appropriate, after an online doctors assessment.

What is Macrobid?

Macrobid is an antibiotic containing the active ingredient nitrofurantoin. It is effective in treating urinary tract infections (UTIs), also known as cystitis. It may also be used long term for preventing UTIs if deemed necessary to deal with chronic cystitis. Macrobid (nitrofurantoin) 100mg is an original branded prescription-only medicine in the UK.

Although cystitis can occur in both men and women it is much more common in women due to having a shorter urinary tract. If men do get cystitis, it is recommended to see a doctor in person as the infection will require a longer treatment and further advice from a doctor.

About Cystitis

These infections are caused by bacteria moving through the urinary tract and into the bladder. In severe cases, this may go further up into the kidneys. Bacteria in the bladder and urinary tract cause inflammation and irritation. This is what leads to the main symptoms of a urinary tract infection. 

These symptoms are:

  • Pain, irritation, burning or stinging while urinating
  • The urge to urinate much more frequently than normal
  • Pain in the bladder
  • Cloudy or dark urine
  • Urine that has a stronger smell than usual

If you are experiencing lower back pain around the side of your back, this could be an indication of a kidney infection. If this occurs, seek medical attention immediately.

Chronic Cystitis

How does Macrobid work?

The active ingredient, nitrofurantoin, collects in the bladder after it is taken, working directly in the area of the infection. It goes into the bacteria cells and disrupts the genetic material (RNA & DNA) of the cell, successfully eliminating the bacteria.

How long does Macrobid take to work?

Generally, most people will notice some relief within 24 hours, with the infection being fully cleared in 3 days. If your symptoms are worsening or are not resolved in 3 days of treatment, it is important you seek a healthcare professionals medical advice.

To ensure the infection is fully cleared, always finish your three-day course of antibiotics, even if you start to feel better. If some bacteria remain, it can cause the infection to come back. Stopping treatment early can also contribute to antibiotic resistance, where the antibiotic will no longer work on certain bacteria.

How to take Macrobid

Take one capsule twice daily for three days. Ensure you take this medicine with food or some milk to lower the stomach upset they may cause. Attempt to take the capsules as close to 12 hours apart as possible over the three-day course. Always finish the full prescribed course of treatment unless you experience any severe adverse effects.

If you forget to take a dose of the medicine and remember later that day, take it once you remember it and continue as usual. If you forget a full days dose, do not double dose the next day, continue as usual. Missing doses does increase the risk of treatment failure. If this happens see your doctor.

Macrobid 100mg Summary


Take 1 capsule TWICE daily for THREE days. Take with food or milk.

Type of Medicine

Antibiotic for UTI


Disrupts bacteria genetic material, killing the bacteria

Active Ingredient

100mg Nitrofurantoin


From £17.48

Side Effects

Can include nausea, stomach upset, headache, loss of appetite

Macrobid alternatives

Besides Macrobid, cystitis can be treated using other types of antibiotics or differing strengths of nitrofurantoin. Whether these are used can depend on if the bacteria are resistant to certain treatments. Bacteria have less resistance to Macrobid than trimethoprim does, meaning it is generally recommended as a first-line treatment under NHS guidelines.

Some alternative treatments to Macrobid are:

Macrobid side effects

Like all medicines, Macrobid can have some side effects. These are mostly mild and will likely go away once you stop taking the medicine. Some more common side effects of the medicine are stomach pain or upset, rashes, loss of appetite, nausea, diarrhoea and headaches.

While being very rare, if you experience any side effects that concern you or are serious, such as an allergic reaction, stop taking the medicine and immediately seek medical assistance.

Symptoms of a serious side effect or allergic reaction can be:

  • Shortness of breath without reason
  • Wheezing (trouble breathing)
  • Sore throat
  • Fever
  • Flu-like symptoms
  • Swelling of the face, lip or neck

For a complete list of side effects, ensure you read the Macrobid PIL.


Tyson Wilkman, Clinical Pharmacist


Tyson Wilkman

RoleClinical Pharmacist
Qual.Bachelor of Pharmacy (Honours)
AboutTyson started with Simple Online Pharmacy in 2021. He's responsible for helping author and review accurate site content. He works with our GPs to make sure all aspects of the medicines are covered.


Can I drink alcohol with Macrobid?

Responsibly drinking alcohol while taking this medicine will not cause harm or reduce the effectiveness of the medicine. It should be noted that drinking alcohol can lead to dehydration which should be avoided during cystitis. Ensure you drink plenty of hydrating fluids until the infection is cleared.

Will Macrobid affect my contraceptive pill?

No, while there are some antibiotics that will affect contraceptive pills, Macrobid is not one of them. Continue your contraceptive medicine as usual.

What if Macrobid does not clear the UTI?

If you are still experiencing UTI symptoms after a course of Macrobid, consult your doctor for medical advice and diagnosis. It may be possible the bacteria infecting the bladder is resistant to nitrofurantoin. Your doctor will be able to test a urine sample to check bacterial resistance.

How long do the side effects of Macrobid last?

The side effects of Macrobid should pass quickly as the medicine is passed quickly out of the body through the urine. If you experience any persistent side effects, consult your doctor or pharmacist.

What is Macrobid used for?

Macrobid (nitrofurantoin) is predominately used to treat or prevent urinary tract infections but may also be used in kidney infections and infections in other parts of the urinary tract.

Does Macrobid come in a tablet?

No, Macrobid only comes as capsules. This is because the capsule is a specially made prolonged-release capsule to ensure the medicine is absorbed properly by the body.


Info Leaflet

Before you use any treatment for cystitis such as Macrobid, you should read the patient information leaflet (PIL) for useful drug information.


Macrobid warnings & precautions

Macrobid may not be suitable for all people. It is advised that you inform our doctors of any medical conditions you have when completing your online assessment so they can ensure the medicine is right for you.

Do not take Macrobid if you:

  • Have any allergies to nitrofurantoin or any other listed ingredient
  • Have severe kidney disease or problems
  • Have any liver problems or disease
  • Are in the final trimester of pregnancy - See your doctor for treatment
  • Have glucose-6-phosphate dehydrogenase disorder (G6PD) or are breastfeeding a child with G6PD
  • Have porphyria
  • Have anaemia or abnormal levels of salt in the blood
  • Have diabetes

There is an increased risk in some patients of developing peripheral neuropathy. You should read the patient information leaflet (PIL) for more information on risk factors.

Other Medicines and Macrobid

Some medications can interact with Macrobid which can change the effectiveness of either medicine. Ensure you list an accurate medicine list when completing the assessment so our doctors can assure the medicine is safe for you.

Some medicines you should be aware of in particular are:

  • Antacids
  • Gout medicines
  • The typhoid vaccine (if given recently or during treatment)
  • Medicines that affect urine acidity 
  • Medicines for glaucoma or eye pressure

Macrobid in Pregnancy

Macrobid may be considered for use in pregnant women by a doctor however, it must not be used during the late stages of pregnancy as it may affect the baby. Consult your doctor before using Macrobid when pregnant or planning to become pregnant.


Macrobid Ingredients

The active ingredient of this medicine is: 100mg of Nitrofurantoin

The other ingredients are: talc, corn starch, lactose, carbopol, povidone, sugar, magnesium stearate, gelatin, Shellac, Titanium Dioxide (E171) Propylene Glycol (E1520), Black iron oxide (E172), E104, E171, E132, Simethicone and Ammonium Hydroxide (E527).

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