The Care Inspectorate raised seven areas of serious concern after an inspection at Acorn Park Care Home in East Kilbride.
It has been warned it must now show "significant improvement".
A Care Inspectorate spokesman said: "Our inspection raised seven areas of significant concern. These were around the administration of medicine; nutrition and hydration; personal plans for service users; infection control; environmental safety; recruitment and fitness of employees; and staffing.
"Everyone has the right to safe, compassionate care which meets their needs and respects their rights.
"Where we have concerns we do not hesitate to take action. Our first priority is always the well- being of residents and this improvement notice sets out what we expect the service to do to ensure that the care provided to residents improves.
"We will be inspecting this service again soon to ensure that progress is being made."
An Acorn Park Care Home spokesman said: "We are working hard with the Care Inspectorate to meet their requirements."