Bio LabPreparing for a liver function test
Reviewed by Dr. Sanaa Ghoneim, Medical laboratory specialist 21 October 2026
Preparing for a liver function test is simple: strict fasting is usually not needed, but follow your doctor’s instructions if fasting is requested, tell us about every medicine, supplement and herbal product you take, and avoid alcohol and hard exercise before the test. These steps help the results reflect your actual condition.
Why preparation matters
Liver tests measure enzymes and proteins that can change for temporary reasons, such as a medicine you took or a hard workout shortly before. When you follow the instructions and tell us everything, you help your doctor read the results with the full picture in mind.
Fasting: needed or not?
Liver function tests usually do not need strict fasting. Some doctors still prefer a fasting sample, especially when other tests are taken at the same time, such as fasting blood sugar or a lipid profile, which are often requested fasting.
So the rule is: follow your doctor’s or our instructions. If all your tests will be drawn together, it is usually simplest to fast and have the sample taken in the morning. Water is allowed either way.
Medicines and supplements: tell us everything
This is the most important part of preparing. Many medicines and supplements can affect liver tests, including:
- Some painkillers and fever reducers.
- Some antibiotics and other long-term medicines.
- Dietary supplements and vitamins.
- Herbs and “natural” products.
Do not stop any medicine on your own. All you need to do is tell your doctor and us about everything you take, even if it seems minor, so your doctor can take it into account when reading the results.
Alcohol and exercise
- Alcohol can affect some liver enzymes, so avoid it before the test.
- Hard exercise, such as a heavy gym session, can affect some enzymes. It is a good idea to leave heavy training until after the draw.
Other things that help
- Drink water before the draw. It makes taking the sample easier.
- Wear a loose sleeve that rolls up easily.
- Have your prescription or test list ready, so we know exactly what is needed.
- Tell us if you have symptoms such as yellowing or ongoing tiredness, and tell your doctor too.
How we take the sample
We review the tests on your prescription and confirm on WhatsApp, before the visit, whether fasting is needed and how to prepare. A technician takes a small blood sample from a vein at your home, and your results reach you on WhatsApp.
About your results
Liver tests are read together, alongside your health and the medicines you take. Discuss the results with the doctor who ordered the test, who will decide whether follow-up or further tests are needed.