The NHS has issued a warning to thousands of people taking the opioid painkiller fentanyl: avoid drinking grapefruit juice. The fruit juice can increase the amount of fentanyl in the body, potentially leading to toxic levels and serious side effects.
Fentanyl is a strong prescription-only painkiller used for severe pain, such as after surgery or a serious injury. It works by blocking pain signals between the brain and the body. In 2022, it was prescribed 812,439 times by NHS primary care services in England.
The NHS advises that while fentanyl is not generally affected by food, grapefruit juice is an exception. Grapefruit contains natural chemicals that slow down an enzyme in the small intestine and liver, causing higher levels of the medication to build up in the bloodstream and stay longer than intended. This can lead to overdose or enhanced side effects.
Common side effects of fentanyl include dizziness, tiredness, and low energy. More serious but rare side effects include muscle stiffness and low blood pressure. Long-term use can lead to tolerance, requiring higher doses. The NHS also warns against drinking alcohol when starting fentanyl, as it increases sleepiness and the risk of serious side effects.
