The practice of forcing psychiatric patients to take medication is not backed by evidence, say UK researchers.
Very few rigorous investigations of the use of coerced medication have been done despite it being widespread, the Journal of Advanced Nursing reported.
The dearth of evidence is "unacceptable" and more should be done to find alternatives, the team said.
A spokeswoman for Mind said the threat of forced medication often stopped people seeking help in the first place.
Researchers from the Institute of Psychiatry and City University in London found 14 studies from seven countries on forcing psychiatric inpatients to take medication.
Most of the patients looked at had been admitted involuntarily, and they were slightly more likely to be female and in their 30s, the studies of patients and staff from the UK, USA, Sweden, Finland, Germany, Canada and Denmark, showed.
Most had been diagnosed with schizophrenia, bipolar disorder or another psychotic illness.
The practice seemed more common in the UK but that is probably because mechanical restraint is used more often in other countries to stop patients harming themselves and others.
There was little detail on the events leading up to the coerced medication incidents and "a complete absence" of investigation into alternatives, the researchers said.
Early intervention
Study leader Manuela Jarrett, a researcher at the Institute of Psychiatry and registered mental health nurse said she had hoped to find more evidence on the factors that lead up to coerced medication, what constitutes a risk and how long the patient has been on the ward.
"We also need more research into early intervention and whether that can prevent coerced medication."
"When you stop and think about it, its quite a drastic step."
She added that hospitals probably had different rates of how often they forced patients to take medication but the figures are not available for monitoring.
The lack of evidence suggests the procedure is taken for granted in psychiatric hospitals, she said.
"We feel that this is unacceptable and more needs to be done to establish sound clinical evidence and viable alternatives to this contentious approach."
Alison Cobb, senior policy and campaign's officer at the mental health charity, Mind, said forcing patients to take medication against their will was "extremely distressing" for them.
"Their freedom is taken away and people are often left feeling powerless, frightened and helpless."
"The threat of coerced medication can discourage people from seeking treatment when they need it and may damage the relationship between patients and mental heath professionals.
"We urgently need to see more studies on this issue, particularly exploring the use of alternative treatments and how to include service users fully in making decisions about treatments."