Why must some medicines be taken on an empty stomach?

Some medicines need to be taken "before food" or "on an empty stomach". This is because food can affect the way these medicines work.

For example, the effectiveness of some medications can be reduced by the presence of food in the stomach because the food prevents the medicine being fully absorbed into the body. Alternatively, some foods – such as grapefruit – can increase the level of medication in your blood to potentially dangerous levels.

As a general rule, medicines that are supposed to be taken on an empty stomach should be taken about an hour before a meal, or two hours after a meal.

However, you should follow the instructions you receive with your medication. If you are unsure how to take your specific medication, speak to your GP or pharmacist (chemist), or phone NHS 111 for advice.

Further information:

Page last reviewed: 09/05/2013

Next review due: 08/05/2015