Hospital staff secretly fed pills to patients by hiding them in their meals and in ice cream, the health watchdog has found.
Queen Alexandra Hospital in Portsmouth has been given a formal warning by the Care Quality Commission over its "very poor care".
In a separate incident, inspectors had to intervene and help a choking patient when two staff members failed to act.
The hospital said it was confident it would be able to improve.
Inspectors, who visited in February, rated medical care at the hospital as "inadequate".
They saw one patient being fed antibiotics in ice cream "covertly without the patient's knowledge".
Two others had medicines secretly mixed with their meals, with no records to support the practice, which is against medical guidelines.
The CQC report raised concerns about two babies being sent home despite having "bruising of unknown origin".
During their visit, inspectors learned of two mental health patients absconding from a unit which treated vulnerable teenagers alongside suicidal adults.
The CQC said previous problems with ambulances queuing to deliver patients had improved thanks to a new "rapid assessment process" in the emergency department.
Safety in urgent and emergency care was rated "inadequate" while the service overall "required improvement", the report said.
Patient Jenny White said in January she witnessed an elderly lady being "torn off a strip" for wetting her bed after being told no commode was available.
Ms White, a former nurse, told the BBC that staff shortages were no excuse for poor care.
But she said her own treatment was "fantastic" after her life was saved by doctors who operated on a burst pancreas.
The CQC's chief inspector of hospitals, Prof Ted Baker, said: "The quality of care on the medical wards was very poor - especially for the most vulnerable patients."
He said a follow-up inspection in May revealed the Portsmouth Hospitals NHS Trust had failed to deal with the inspectors' concerns.
The CQC has ordered the trust to send weekly progress reports and warned further enforcement action may be necessary to protect patients.
Trust chief executive, Mark Cubbon, said: "The report makes for difficult reading and we have fallen short in some key areas, but I am confident that we can and will do better."