Tyneholm Stables Care Home in Pentcaitland, East Lothian, was criticised by a watchdog for failing to provide basic care such as giving residents enough water and ensuring people at risk of choking were fed the right food.
The Care Inspectorate said a quarter of staff who were giving residents medication had no basic training to do so, surfaces were dirty, bathrooms had no handwashing facility and the wrong bins were used for continence aids, wipes, gloves and dressings, creating risk of infection.
The home was described as unsatisfactory in all care themes and faces closure if it fails to improve.
A spokesman for the Care Inspectorate said: "An unannounced inspection of this service raised serious concerns.
"Everyone in Scotland has the right to safe, compassionate care, which meets their needs and respects their rights.
"We will be inspecting this service again soon to ensure that progress is being made."
The Care Inspectorate said the home operators European Care agreed to voluntarily halt new admissions while East Lothian Council said it would put a moratorium on referrals.
An East Lothian Council spokeswoman said it was "continuing to monitor the situation at the home to ensure residents receive good quality care".
A spokesman for the home said: "The health and wellbeing of the people we support is our number one priority ."