Timing of Drugs - Before or After Food

Because food can interact with drugs in different ways, perhaps making the drugs more or less effective, it can be very important to take the drugs as recommended - before, after or with food.

Always follow the instructions on drugs labels, and if in doubt, talk to a doctor or pharmacist.

Taking Drugs Before Food

Some drugs need to be absorbed quickly to have an effect, such as nitrates in angina, drugs to help sleep (hypnotics), drugs to reduce agitation (sedatives), and painkillers (analgesics). As food can slow the absorption of these drugs (see also ‘Fatty Food and Drugs’, ‘High Fibre Diets and Drugs’ and ‘High Protein Diets and Drugs’), they need to be taken on an empty stomach.

Taking Drugs With or After Food

Some foods can delay the emptying of the stomach into the small intestine, where most drugs and nutrients are absorbed. This means that the stomach contents, including the drug, are exposed to stomach acid for longer, which can have different effects on different drugs.

The acid in the stomach breaks down some drugs, so delayed emptying will mean that more of the drug is broken down, and less of the drug is available, so it will be less effective. The acid in the stomach also changes some drugs, making them more soluble and so more easily absorbed. This means that the drug will be more effective, but could potentially also cause more side effects.

NSAIDs (non-steroidal anti-inflammatory drugs – used in pain and inflammation), diuretics (used in high blood pressure), some antibiotics, and corticosteroids (used in inflammation and allergy) can cause stomach upsets. Taking these drugs, such as ibuprofen, with food (or milk) can reduce the irritation to the stomach lining.

According to a study carried out in the USA in 2007, taking lapatinib (a drug used in the treatment of breast cancer) with food, especially fatty food (see also ‘Fatty Food and Drugs’), could reduce the side effect of diarrhoea and lower the dose needed, which may potentially save money on treatment. According to the researchers, following up the meal and tablets with a glass of grapefruit juice (which changes the way the body breaks down the drug) could make one tablet have the same effect as five tablets taken on an empty stomach. Patients should only change their pattern of taking drugs after discussion with a doctor or pharmacist.

Some drugs have to be taken during or after meals to be effective – for example, orlistat is designed to block the absorption of some of the fat in food as a treatment for obesity. However, if it is taken with a high fat meal this can cause unpleasant side effects.

Taking the right number of doses of the drug at the right times (known as ‘adherence’), is very important for the effectiveness of treatment. Taking drugs with or after meals can help people establish a routine and remember their treatments. Some people take drugs at bedtime or when they first get up for a similar reason.