Macrobid S/R
  • Macrobid S/R


Medication features

  • Twice daily dosage
  • Three-day course
  • For bacterial infections in the urinary tract (UTIs/Cystitis)
  • Better value generic Nitrofurantoin available in 50mg strength


Buy Macrobid 100mg Online in the UK

You can buy Macrobid 100mg for 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.

If our doctors decide the medicine is not right for you or you may benefit from a face to face consultation, a full refund will be given on your antibiotic.

What is Macrobid?

Macrobid is an antibiotic containing the active ingredient nitrofurantoin. This medicine is effective in treating urinary tract infections (UTIs), also known as 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. Macrobid moves through the bladder and eliminates the bacteria and is then passed out in the urine.

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.

Symptoms of Cystitis

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.

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 infective 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 of treatment. 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.

Macrobid Summary


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


Disrupts bacteria genetic material, killing the bacteria

Active Ingredient

100mg Nitrofurantoin



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:

Chronic Cystitis

Alcohol and 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.


  • What is cystitis?

    Cystitis is the name for bladder inflammation, usually caused by a bladder infection. 

    Mild cases of cystitis often improve within 3 days but more severe cases can last longer. If your symptoms do not improve within 3 days, you should speak to a doctor.

  • Can cystitis cause any complications?

    Cystitis in men is usually an indication of a more serious problem and requires medical help from your GP. It can also be caused by STIs which can have other complications. Men should see their GP if they suffer from cystitis.  

    Women can use treatment without face to face referral but if it doesn’t clear up, medical advice is needed. This is because if left untreated after it hasn’t cleared up, it can lead to a serious kidney infection.

  • What treatments are there for Cystitis?

    For milder cases, treatment with potassium citrate sachets may be sufficient. For more stubborn infections, a course of water infection tablets such as Trimethoprim may be required.

  • What is the best antibiotic for cystitis?

    This depends on what bacteria is causing your infection. The most common type of bacteria which causes uncomplicated UTI’s is E. coli. The antibiotics which are given to treat this bacteria are Trimethoprim or Nitrofurantoin. If your symptoms do not improve after completing a course of these antibiotics, it is important to see your GP to have your urine tested in case it is a different bacteria that needs a different antibiotic.

  • Can I get UTI antibiotics online for cystitis?

    Our UK registered online doctor service can offer antibiotic treatment. We ask that you complete an online medical assessment for our doctors to review. If suitable, our doctors will write a prescription and send it to our UK pharmacy. Your medicine will then be dispatched to your chosen address. 

Side Effects

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
  • Skin reactions (rashes)
  • Loss of appetite
  • Nausea
  • Diarrhoea
  • Headache

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
  • 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.


Info Leaflet

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


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.

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 warnings & precautions

Do not take Macrobid if you:

  • Have any allergies to nitrofurantoin or any other listed ingredient
  • Have severe kidney 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 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).

Order on Monday to Friday until 3:30pm guarantees next day delivery options

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