Commonly-prescribed painkillers can triple the harmful side effects in people with dementia, new research suggests.
Scientists found a significant rise in side effects such as personality changes, confusion and sedation, which can seriously impact people's lives in dementia.
Around half of people with dementia who are living in care homes experience clinically significant pain.
Previous research has recognised that pain is often under-diagnosed and poorly managed in people with dementia, impacting on quality of life.
After paracetamol, opioid-based painkillers are often the next line of treatment for clinicians in people with dementia and are prescribed to up to 40% of people with dementia living in care homes.
They ease pain effectively, yet current prescribing guidance does not take into account the fact that people with dementia get effective pain relief from smaller doses than are commonly prescribed and are particularly sensitive to adverse effects.
Scientists at the University of Exeter, King's College London and the University of Bergen are now calling for studies to examine appropriate dosing of painkillers such as buprenorphine for people with dementia.
Their study examined 162 people from 47 Norwegian care homes who had advanced dementia and significant depression.
In those who were assigned buprenorphine as part of their treatment pathway, harmful side-effects more than tripled.
The researchers also found that those taking buprenorphine were significantly less active during the day.
Professor Clive Ballard, from the University of Exeter, said: "Pain is a symptom that can cause huge distress and it's important that we can provide relief to people with dementia.
"Sadly at the moment we're harming people when we're trying to ease their pain.
"We urgently need more research in this area, and we must get this dosing right.
"We need to establish the best treatment pathway and examine appropriate dosing for people with dementia."
- The study, A Randomised, Placebo-Controlled Trial to Investigate Safety in People with Dementia or Buprenorphine Transdermal System for Pain Management, is being presented at the Alzheimer's Association International Conference 2018 in Chicago