Grapefruit juice and atorvastatin: how much is too much?

Grapefruit juice has a reputation in medicine safety because it can change the amount of certain medicines that reaches the bloodstream. The BNF records this as grapefruit juice increasing the exposure to a medicine, using the same wording as for drug-drug interactions. The BNF interaction lists treat it as an interacting substance in its own right.

This is a pattern the NHS reflects across its medicine pages. Colchicine, verapamil, nifedipine and sertraline all carry a warning about grapefruit, and the NHS warfarin page says not to drink grapefruit juice. Atorvastatin is different only in that the advice is a limit rather than a ban.

The NHS atorvastatin page says you can eat as normal while taking it, but to avoid having too much grapefruit juice because it can increase the chance of side effects. It says not to have more than 1 or 2 small glasses of grapefruit juice a day, and also asks you to limit alcohol because it can increase the risk of side effects such as liver problems.

The BNF entry for atorvastatin says grapefruit juice increases the exposure to atorvastatin and that the manufacturer advises caution, with severity mild and evidence type study. The wording caution and mild fits the NHS stance of a daily limit rather than complete avoidance.

The sources read for this guide do not give a figure for whole grapefruit or for other citrus. If you eat grapefruit regularly, or drink it in large amounts, ask a pharmacist.

For simvastatin the position is stricter. The NHS simvastatin page says to avoid drinking grapefruit juice, and the BNF says grapefruit juice increases the exposure to simvastatin with advice to avoid, rated severe. A person who switches between statins should not assume that the atorvastatin limit carries over.

This site has a separate guide to grapefruit and statins, and one on grapefruit juice and medicines generally, for readers who want the wider picture.

The NHS lists inflammation of the liver, inflammation of the pancreas and inflammation and damage to the muscles among possible serious side effects of atorvastatin. For the muscles it describes cramps, severe pain and weakness, with a possible high temperature and red or brown pee. It says to call NHS 111 if you think you might be having serious side effects.

Yellowing of the skin and the whites of the eyes can be a sign of liver inflammation, and the NHS notes yellowing may be less noticeable on brown or black skin. Severe stomach pain can be a sign of pancreatitis.

Keep a note of what you drink regularly, since a daily glass can be easy to forget. Do not stop atorvastatin because of a glass of juice. Ask a pharmacist if you have changed how much grapefruit you consume or if you have started another medicine that raises statin levels. The NHS also says that if you recently started a medicine you can get help with newly prescribed medicines from a pharmacist as part of the New Medicine Service.