In 2014, Sarah Rochira published the results of a major review of the experience of care home residents.
The use of antipsychotic drugs was a recurrent theme which she has branded a "national scandal".
Health boards and care homes have said changes are being made.
The commissioner is asking them to show significant improvements in practice.
"I know professionals don't like this phrase, but across Wales older people in care homes, through the inappropriate use of these drugs, are being 'chemically coshed'. That's the reality of it.
"It is a national scandal. I made that clear when I published my review. I was very clear I would come back and look for evidence of changes and I've now begun that process.
"I will publish the findings from the health boards later this year and I cannot be any clearer in my expectation that they understand how inappropriate the current situation is and that they can evidence real progress."
Antipsychotic drugs are primarily used to treat conditions such as schizophrenia and bipolar disorder.
A survey last November by the Royal College of Psychiatrists found nearly one in five - 18% - of dementia patients were being prescribed antipsychotics.
The Royal Pharmaceutical Society in Wales published its own report into the use of medicines in care homes following the Ms Rochira's report.
The society's director in Wales, Mair Davies, told BBC Radio Wales' Eye on Wales programme that there were examples of expert practice.
"What we need is to make sure that happens in every care home in Wales," she said.
Steve Ford, the dementia care lead for Care Forum Wales, which represents more than 450 independent care homes in Wales, believes progress is being made.
"We need to look at the underlying reasons for unwanted behaviour that challenges, rather than picking up the phone to the GP and requesting those prescriptions," he said.

Jon Schueler, who died in New York in 1992 at the age of 75, created many of his pieces from a studio in Mallaig in the Highlands.
He was inspired by views of the Sound of Sleat and also of Skye, which lies across the stretch of sea.
An arts symposium and exhibition at the college runs from Friday to Sunday.
Called An Linne: Echoes, Reflections and Transfigurations, the events mark the centenary of the artist's birth in Milwaukee, Wisconsin, in 1916.
The painter, who served as a navigator on US bombers flown out of England during World War Two, moved to Mallaig in 1957 and he continued to visit and work in the village in the north-west Highlands throughout his career.
Many of his pieces were influenced by the changing weather on the west coast and the effect the conditions had on the sea.
Magda Salvesen, curator of the Jon Schueler Estate, said: "The Sound of Sleat became to Schueler a place of experience, memory and mood.
"The specificity of this body of water fed Schueler's paintings - their imagery enlarged through layers of memory.
"How appropriate and challenging that the symposium celebrating the artist's centenary should be held on Skye, an island seen through changing weather from his studio in Mallaig."
The celebration at SMO - Scotland's National Centre for Gaelic Language and Culture, and which offers a Jon Schueler Residency scholarship - includes talks on Schueler's life and work and an exhibition of selected pieces from his time in Mallaig.
Donnie Munro, director of development, fundraising and the arts at SMO, described the artist as having a "profoundly deep experiential affinity with the Sound of Sleat".
He said this connection led Schueler to create some of his most celebrated works.
Evidence of progress on reducing the inappropriate use of antipsychotic medication in care homes has been demanded by the Older People's Commissioner for Wales.
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The life and work of an American Expressionist painter is being celebrated at Skye's Gaelic college Sabhal MÃ²r Ostaig (SMO).