A man sprayed in the face with a police CS canister may be permanently scarred by the burns and must avoid daylight for 12 months, say his family.
Mr Ford has been left with horrific scars on his face
Dan Ford, 21, of Wareham, Dorset, was sprayed when he tried to intervene as officers questioned a friend.
Dorset Police said Mr Ford, who has been charged with a public order offence, had suffered an unusually adverse reaction to the spray.
The Independent Police Complaints Commission is now looking at the case.
Mr Ford had been drinking with his sister Rachel and his cousin Donna Lewis when he saw a friend being questioned by police.
He was among several people subsequently sprayed with CS, commonly known as "tear gas".
Miss Lewis said the canister was sprayed close to Mr Ford's face in a long burst.
He was taken to Poole police station and remained there overnight before being charged.
Miss Lewis, from Corfe Castle, said his face was swollen and red raw the next day.
"To look at him, it was like looking at a melting man.
"He was continuously mopping his face, with liquid oozing from his face.
"It was disgusting to look at and quite heartbreaking," she said.
Doctors at Salisbury District Hospital's specialist burns unit - where Mr Ford was treated - believe he will be scarred for life because the spray caused his skin to blister severely, say the family.
Mr Ford has been told he cannot go out in daylight for over a year, which means he cannot work.
His father is now considering launching a civil action against Dorset Police.
Adrian Whiting, assistant chief constable of Dorset Police, described Mr Ford's reaction to the spray as "unusually adverse".
He added: "We are committed to maintaining public safety, and occasionally we have had to make use of incapacitating sprays."
Mr Ford was seen by a police doctor at his father's request before being released, he said.
He was taken to Poole Hospital, but the severity of the burns led to him being transferred to Salisbury Hospital.
A Home Office spokesperson said: "The physical effects of the spray are unpleasant but its use can be justified where there is a risk of serious injury to the police or public."