Antipsychotic-induced weight gain is monitored more often than it is treated. The weight is recorded, the trend is noted, and the response is usually advice about diet or a conversation about switching antipsychotic that risks destabilising someone who is finally well.
There is now moderate-certainty randomised evidence for drug treatment of it, and the practical options are not exotic. Metformin, with sixteen trials behind it, gives around 3.9 kg and reaches clinically meaningful weight change; it is cheap, familiar and already in most formularies. Semaglutide gives considerably more where it is available and affordable. Topiramate and the other GLP-1 agonists sit between them.
So when the weight has climbed, treat it as a treatable problem with its own drug options, rather than as a side-effect to be tolerated or a reason to disturb an effective antipsychotic. Record the baseline weight when starting an antipsychotic, so that the trend is visible early enough to act on rather than discovered years later.
- Record a baseline weight when starting any antipsychotic
- Metformin: about 3.9 kg, sixteen trials, cheap and widely available
- Semaglutide gives more where affordable; topiramate is an alternative
- Treat the weight rather than destabilising an effective antipsychotic
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