Pentland Hill in Edinburgh was issued with an improvement notice in August after the Care Inspectorate raised concerns about standards at the home.
Police are also investigating the deaths of four residents at the Bupa-run home, which has also been the subject of complaints by other families.
A new inspection report warned that unless further improvements were made the home could be closed down.
Bupa said significant changes had been made since the inspectors last visited six weeks ago. The inspection took place at the start of October, but the report has only just been made public.
Assessing the service, the Care Inspectorate rated the quality of care and support and the quality of management and leadership as “unsatisfactory”, while the quality of environment and staffing were both rated as “weak”.
Their report said: “At this inspection, we found evidence that BUPA, the provider, was taking steps to make the necessary improvements.
“While we found some positive changes, these were not significant enough to meet the necessary improvements in outcomes for people at Pentland Hill Nursing Home.”
The service was given until tomorrow (28th Nov) to make the necessary improvements and will face a further inspection shortly to make sure changes have been made.
A Care Inspectorate spokesman said:“This report shows evidence of some change to how the home is run and managed, including better external support and a new manager, but we are still not satisfied by the overall quality of care being delivered.
“Our team of 11 inspectors and healthcare specialists found poor practice in medication, tissue viability and at mealtimes, and our report makes sober reading.
“The quality of care, staffing and leadership remains unsatisfactory.
We therefore require further, specific improvements this week, after which we will reassess the home’s licence to operate.”
The inspectorate said if it did not see “immediate further evidence of significant improvement” the home faced closure.
Andrew Cannon, managing director of Bupa Care Services, said: “This report follows an inspection completed over six weeks ago.
“Since then we have continued to make improvements to the home which the Care Inspectorate report has recognised. Our residents and their families tell us they are also seeing a difference from all the changes.
“Our new home manager and her team will continue working with the Care Inspectorate to embed all the improvements so that high standards of care are achieved and maintained.”