A yob claiming to have coronavirus spat on a pharmacy worker then threatened to shoot him and burn down the building.
When police arrested him he stuck the head on a seat and belted himself with his handcuffs.
An investigation into the officers' handling of the incident found they acted proportionately when they arrived at the scene in Glasgow earlier this month.
The Police Investigations and Review Commissioner (Pirc) agreed the man's injuries were self-inflicted following their probe.
Their report reveals that the 32-year-old man entered the pharmacy at around 1.25pm, ignored social distancing rules and demanded methadone for the entire weekend, which was refused.
He then became verbally abusive before leaving but returned a short time later and spat and coughed at a member of staff.
A member of the public removed him from the pharmacy and the man threatened to shoot him and burn down the building.
Police were called to the incident and arrested the man, who claimed to have coronavirus.
He was taken to the police van in handcuffs and then deliberately struck his head on a seat - causing a cut to his forehead - before hitting his head with the cuffs.
The man was taken to hospital, where officers wore full personal protective equipment (PPE) before entering.
Following treatment to the cut on his forehead, the man was released into police custody and later charged.
The incident was referred to Pirc by Police Scotland on Monday, May 11.
In the report, investigators found the man's injuries were self-inflicted with concerns over his behaviour.
The police officers' response was also deemed "proportionate and necessary".
Commissioner Michelle Macleod said: "This man's behaviour was extremely concerning and distressing for the pharmacy staff and arresting officers given the seriousness of the current Covid-19 crisis.
"The police officers involved conducted themselves professionally and their response was proportionate and necessary in the face of extreme provocation."
Assistant chief constable Steve Johnson said: "Police Scotland is supporting a national effort to combat the spread of coronavirus and the vast majority of people are doing their part to protect the NHS and save lives.
"Threats against key workers performing essential duties are completely unacceptable and will not be tolerated.
"The actions of the officers who responded to this incident were professional, necessary and proportionate and I am pleased that this has been confirmed by the Pirc."
