Some antipsychotic medication may increase the risk of death in patients with dementia more than others, according to US research.
The drugs have a powerful sedative effect so are often used when dementia patients become aggressive or distressed.
A study, published on the BMJ website, argued that antipsychotics should not be used "in the absence of clear need".
Experts said better alternatives were needed to antipsychotics.
A study in 2009, suggested 180,000 people with dementia were taking antipsychotic medication in the UK and said the drugs resulted in 1,800 additional deaths.
Researchers at Harvard Medical School followed 75,445 people in nursing homes who had dementia and were prescribed antipsychotics.
The researchers said some drugs were associated with more than twice the risk of death than risperidone, another antipsychotic which was used as a benchmark to compare the other drugs.
The study concluded: "The data suggest that the risk of mortality with these drugs is generally increased with higher doses and seems to be highest for haloperidol and least for quetiapine."
However, the way the study was conducted meant it could not say definitively that certain drugs actually caused more deaths, merely that there was a link between the two.
The Department of Health said antipsychotic use was "resulting in as many as 1,800 unnecessary deaths per year. This is simply unacceptable."
"That's why reducing the level of antipsychotics prescribing for people with dementia by two-thirds is one the key priorities in the National Dementia Strategy."
The Dementia Action Alliance - which includes the Alzheimer's Society, Age UK and the Department of Health - has called for all prescriptions for antipsychotics to be reviewed by the end of March 2012.
Dr Chris Fox, who researches dementia at the University of East Anglia, said: "This study provides an interesting insight into the differential harm of these medicines.
"More work is needed on alternatives to these medicines in dementia with behavioural problems.
"In addition, there is a need to consider duration of use in more acute situations such as severe distress. Is six or 12-week use safe in people with dementia?"
Alzheimer's Research UK's chief executive Rebecca Wood said the risks of antipsychotics were "well-established" yet "progress has been frustratingly slow" in reducing their use.
She said the drugs "should only be used for people with dementia where there is no alternative for dealing with challenging behaviour".
Dr Anne Corbett, research manager at Alzheimer's Society, said: "For a minority of people with dementia antipsychotics should be used, but then only for up to 12 weeks, and under the correct circumstances. For the majority, they do far more harm than good."