The NHS has issued a warning to people taking fentanyl, one of the UK's most commonly prescribed strong painkillers, advising them not to drink grapefruit juice while on the medication. The fruit juice can increase the amount of fentanyl in the body, potentially turning levels of the medicine toxic without the patient realising.
Fentanyl is an opioid painkiller used to treat severe pain, such as after an operation or a serious injury. It is prescribed by doctors and works by blocking pain signals between the brain and the rest of the body. The medication is available in various forms, including lozenges, tablets that dissolve in the mouth, skin patches, and nasal sprays.
The NHS website states that, like all medicines, fentanyl can cause side effects in some people, though many users experience none or only minor ones. More serious side effects, such as muscle stiffness, dizziness, tiredness, or low energy (which can indicate low blood pressure), are rare. Long-term use may lead to tolerance, requiring higher doses over time.
While fentanyl is not generally affected by food, the NHS specifically warns against consuming grapefruit juice. Grapefruit contains natural chemicals that slow down an enzyme in the small intestine and liver called cytochrome, causing higher levels of the drug to build up in the bloodstream and stay in the body longer than intended. This increased concentration can lead to an overdose or enhanced side effects.
Patients are also advised to avoid alcohol when first starting fentanyl, as it can increase sleepiness and the risk of serious side effects. It is generally safe to take fentanyl with painkillers like paracetamol, ibuprofen, or aspirin, but those containing codeine, such as co-codamol, should be avoided.
