Some medicines should be taken with food or just after food. Some medicines should be taken on an empty stomach. It's important to follow these instructions to make sure that your medicine works well and to help protect you from unwanted effects.
What does 'on an empty stomach' mean?
Some medicines need to be taken 'before food' or 'on an empty stomach'. If the instructions say that you should take your medicine on an empty stomach, take it at least an hour before or 2 hours after a meal.
You can eat first and take the medicine an hour later
take the medicine first and eat 2 hours later.
Why should some medicines be taken on an empty stomach?
Taking some medicines at the same time as eating may prevent your body absorbing the medicine, and it may not work as well as it should. This is because food, and even some drinks, can affect the way these medicines work.
Here are examples of some medicines that are best taken on an empty stomach, although there may be others that are not on this list:
- thyroxine (also called levothyroxine or Eltroxin®)
- Fosamax (also called alendronate)
Forgetting these instructions on rare occasions is unlikely to do any harm, but taking these medicines with food regularly may mean they won't work so well.
Taking medicines with or after food
If the instructions say to take your medicine with or just after food, a small amount of food is usually enough.
Why should some medicines be taken with food?
Here are common reasons why some medicines should be taken with food.
- To reduce side effects of nausea or vomiting. With medicines that can cause nausea or vomiting, taking the medicine after a meal can reduce these side effects. Examples include allopurinol and metronidazole.
- To reduce side effects of stomach upset, including indigestion, stomach inflammation or ulcers. Some medicines can irritate your stomach, and taking them with food reduces this effect. Something like biscuits, a sandwich or a glass of milk is usually enough. Medicines that can cause an upset stomach include:
- To treat problems such as heartburn, reflux or indigestion. Medicines called antacids are taken to prevent heartburn, reflux and indigestion, which usually occur when acid is produced as food enters your stomach. Therefore, these medicines are most effective if taken immediately after, or during, a meal.
- To ensure the medicine is absorbed into your bloodstream properly. You need food in your stomach and gut for your body to absorb some medicines properly.
- To help your body process the meal. Some medicines for diabetes, if taken by mouth, should usually be taken around mealtimes to reduce blood sugar levels after eating and to avoid very low blood sugar (hypoglycaemia). Enzyme supplements, which can be used to help people with chronic pancreatitis, should also be taken with food to help your body process the meal.
- Medicines: common questions answered National Institute of Aging
- Why must some medicines be taken with or after food? NHS, UK
- Why must some medicines be taken on an empty stomach? NHS, UK