If you’ve been reading about naltrexone late at night and landed on the BNF, here’s the short version. The naltrexone BNF entry is the official UK reference doctors and pharmacists use, and it lists what the drug is licensed for, how it’s thought to work, and what side effects to watch for. It’s written for clinicians, not for a worried man on his phone, so it can feel cold and dense. This is the same information, said plainly.
What does the BNF say about naltrexone?
The BNF describes naltrexone as an opioid receptor blocker, licensed in the UK mainly to help people stay off opioids and to support people cutting down on alcohol.
BNF stands for the British National Formulary. It’s the standard reference UK prescribers reach for when they want the facts on a medicine: the licensed uses, the doses, the cautions, and the side effects.
The BNF entry is a clinical reference, not a verdict on you. It tells a doctor how a medicine behaves; it doesn’t decide whether it’s right for any one person.
One thing worth knowing early. Using naltrexone for compulsive porn use is off-label. That means it’s being used outside its official licence, based on a clinician’s judgement rather than a formal approval. That’s not unusual in medicine, but it’s a decision only a prescriber can make with you.
How does naltrexone work, according to the guidance?
According to the guidance, naltrexone works by blocking opioid receptors in the brain, which are part of how the brain registers reward and pleasure.
Here’s the everyday version. When you do something the brain finds rewarding, it releases chemicals that make the moment feel good and make you want to repeat it. Naltrexone sits on some of those receptors and quietens that signal.
The thinking behind using it for compulsive behaviours is that it may take some of the pull out of the loop. The urge that feels automatic. The 2am scroll you didn’t quite decide to start, might feel a little less loud.
This is a mechanism, not a magic switch. The evidence for naltrexone in behaviour like compulsive porn use is still emerging, and it isn’t a cure on its own. It tends to be used alongside real behaviour change work, not instead of it. That’s why our Norm programme is built around CBT-based tools, with medication only ever a support where a clinician judges it right.
What does the BNF list as naltrexone’s side effects?
The BNF lists a range of possible side effects for naltrexone, and most are mild and settle as your body adjusts. Common ones can include:
- Nausea or stomach upset
- Headache
- Trouble sleeping
- Feeling anxious or low in mood
- Tiredness or dizziness
Less commonly, the guidance notes effects on the liver, which is why a clinician may check your liver function before and during treatment.
Side effects are real but they’re managed, not ignored. A prescriber weighs them against the benefit for you, starts carefully, and adjusts if needed.
The full, up-to-date list lives in the BNF itself, and it can change as new evidence comes in. If you’re considering naltrexone, the safest move is to read the current entry with a clinician rather than trust a summary alone. They’ll know your history and can spot what matters for you.
