How and when to take nitrofurantoin

The dose of nitrofurantoin you take depends on whether it's to treat or prevent a urinary tract infection, your age, and how bad the infection is.

Tablets and capsules contain either 50mg or 100mg of nitrofurantoin. The slow release capsules are 100mg. The liquid contains 25mg in 5ml.

The usual adult dose to treat a urinary tract infection is:

• 100mg, taken as slow release capsules, twice a day
• 50mg, taken as standard tablets or capsules, 4 times a day
• 100mg, taken as standard tablets or capsules, 4 times a day, for severe infections

The usual adult dose to prevent a urinary tract infection coming back is 50mg to 100mg, taken as standard tablets or capsules, once a day at night.

In adults, nitrofurantoin can be given as a single dose of 50mg or 100mg for the prevention of recurrent urinary tract infection following exposure to a trigger.

Doses are usually lower for children. Your child's doctor will work out the correct dose based on your child's weight or age.

Try to space your doses evenly throughout the day. If you're taking nitrofurantoin twice a day, leave 12 hours between each dose – for example, take it at 8am and 8pm.

If you're taking it 4 times a day, this will usually be first thing in the morning, at about midday, late in the afternoon, and at bedtime.

Swallow nitrofurantoin tablets or capsules whole . Do not chew or break them.

If you're taking liquid nitrofurantoin, the medicine will come with a syringe or spoon to help you take the right amount. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a teaspoon as this will not measure the right amount.

Take nitrofurantoin with or after a meal or snack. This helps your body absorb the medicine, as well as helping to prevent an upset stomach.