Why do I need to take certain medicines with or without food?

by | Sep 13, 2022 | Medicine

You are probably aware that some medicines from your pharmacy need to be taken with food while others should be taken on an empty stomach. But what are the reasons for this? And why is it so important that you follow these instructions?

Medicines that need to be taken with food

Certain medicines need to be taken with food to reduce side effects such as nausea, vomiting and irritation of the gut lining.¹ Examples of medicines that irritate the gut lining include aspirin and non-steroidal anti-inflammatory drugs (NSAIDs), such as Nurofen® (ibuprofen) and Voltaren® (diclofenac).¹ Irritation of the gut lining can lead to indigestion, stomach inflammation and ulcers.¹

If you have a history of gastrointestinal issues, you may need to be extra cautious when taking medicines that irritate the gut lining.² This is because these medicines weaken the ability of the stomach lining to resist acid made in the stomach.³ In some cases, this can then lead to inflammation of the stomach lining (known as gastritis), ulcers, bleeding or perforation of the lining.²

Certain medicines may also need to be taken with food to help ensure that the medicine is properly absorbed into the bloodstream.¹

Medicines that need to be taken on an empty stomach

Other medicines may need to be taken on an empty stomach because they interact with food in some way.³ For example, some antibiotics, such as flucloxacillin (a drug used to treat bacterial infections), don’t work as well if taken with food.³ In addition, levothyroxine (a drug used to treat hypothyroidism), and some osteoporosis medicines (such as alendronate) don’t work as well when taken at the same time as calcium-rich foods, such as milk and yoghurt, and calcium supplements.³

Why should you drink a glass of water with your medicine?

It is recommended that you take your medicine with a full glass of water.² This may help reduce the risk of irritating the gut lining.² It will also help you swallow your medicine.² This is important because tablets or capsules that stay in the oesophagus may release chemicals that can irritate the lining of the oesophagus.² Certain medicines, for example aspirin and certain antibiotics such as doxycycline (which is commonly prescribed for malaria or for acne), can even cause ulcers in the oesophagus if they become lodged there.²

Ensuring you get the most from your medicines

All medicines have specific instructions about when and how you should take them. It is important that you understand these instructions, remembering that all medicines are different so will have different instructions.

Make sure you also talk to your doctor or ask our Pharmacist a question if you have any questions about how to take your medicines.


1. NHS. Available at: https://www.nhs.uk/common-health-questions/medicines/why-must-some-medicines-be-taken-with-or-after-food. Accessed August 2022.

2. John Hopkins Medicine. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/medicines-and-the-digestive-system. Accessed August 2022.

3. NPS MedicineWise. Understanding drug interactions. Available at: https://www.nps.org.au/consumers/understanding-drug-interactions. Accessed August 2022.

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Medically reviewed by Dr Matt Cullen

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