How and when to take trimethoprim

Trimethoprim tablets contain 100mg or 200mg. The liquid contains 50mg in 5ml.

To treat urinary tract infections (UTIs) in adults, the usual dose is 200mg twice a day.

To prevent infections, the usual adult dose is 100mg once a day at night.

If you know what causes your cystitis, take one single dose of 200mg after you’ve been exposed to the trigger.

To treat acne, the usual adult dose is 300mg twice a day. This dose might be reduced over time.

The dose of trimethoprim you need to take depends on your condition, your age, and how well your kidneys work.

Doses are usually lower for children, older people and those with kidney problems.

Stopping trimethoprim

Carry on taking this medicine until you finish the course, even if you feel better. If you stop your treatment early, your problem could come back.

How to take trimethoprim

Trimethoprim tablets

If you're taking trimethoprim to treat an infection, you'll usually take it twice a day, once in the morning and once in the evening.

If you're taking trimethoprim once a day to prevent an infection, take it at bedtime.

If you know what triggers your cystitis and want to stop an infection before it starts, take trimethoprim as a single dose after being exposed to the trigger.

You can take trimethoprim with or without food.

Swallow trimethoprim tablets whole with a drink of water. Do not chew or break them.

You can take it as a liquid if you find it difficult to swallow tablets.

Trimethoprim liquid

If you're taking trimethoprim as a liquid, shake the bottle gently before measuring out the right amount using a medicine spoon or oral syringe. If you do not have an oral syringe or medicine spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.