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Detailed medicine guidance

How and when to take Fybogel

NHS medicines information on dosage for Fybogel, how to take it and what to do if you miss a dose or take too much.

About this information

This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.

Dosage and how to take Fybogel

Dosage

The usual dose of Fybogel for constipation is:

  • for adults and children aged 12 years and over – 1 sachet of granules twice a day
  • for children aged 6 to 11 years – half to 1 level (5ml) teaspoonful of granules twice a day
  • for children aged 5 years or under – half to 1 level (5ml) teaspoonful of granules twice a day, only if recommended by a doctor

How to take Fybogel

It's best to take Fybogel after a meal or snack and at least 30 minutes before or after you take any other medicine.

To make up the medicine, open the sachet and empty the amount of granules you need into a glass. Add at least 150ml of cold water to the glass.

Stir well until all the granules have dissolved and the Fybogel solution is clear or slightly hazy, then drink it immediately.

Try not to breathe in the powder when you make up the Fybogel drink, because there's a small chance this could trigger a mild allergic reaction.

Have your evening drink of Fybogel at least an hour before going to bed. Do not drink Fybogel just before you go to sleep because this can make it harder for your bowel to move the poo along.

It's important to drink extra fluid if you're taking Fybogel. Adults should try to drink more than 2 litres, or around 8 glasses, of fluid each day. If you do not drink enough fluid while taking Fybogel, your constipation may get worse.

View the original NHS website page ↗. Refreshed 19 August 2026.

Licensed under the Open Government Licence v3.0 ↗. MyPHU is independent and is not endorsed by the NHS.

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