A man who fell into a coma during a drugs trial last month has said he may lose parts of his fingers and toes.
Six men suffered multiple organ failure after the trial
Ryan Wilson, 20, from London, was the most seriously ill of six men whose heads and bodies swelled up following injections of TGN1412.
He told the News of the World he could need to stay in hospital for six more months as his condition is monitored.
"They're waiting for my body to heal," he said. "I'm told it's like frostbite and my fingers will just fall off."
Photographs in the newspaper show Mr Wilson in bed at Northwick Park Hospital, north west London, with his blackened feet and hands.
"The doctors say they don't want to take my fingers off because that's messier than if the body sorts itself out, " he told the paper.
"So if the fingers fall off they'll actually heal better.
"They're waiting for pink flesh to move further up the feet, but the tips of most of my toes are basically dead. So at the very least I'll lose them."
Mr Wilson was among the volunteers to have been given the TGN1412, created by German pharmaceutical company TeGenero, by medical research company Parexel.
The previously healthy men had volunteered to test the medication, which was designed to treat rheumatoid arthritis, leukaemia and multiple sclerosis.
Mr Wilson said he took part in the trial, which paid £2,000, to fund driving lessons and a holiday.
He suffered heart, liver and kidney failure, pneumonia, septicaemia, and was ventilated on 99% oxygen.
Doctors then tried to save him from dry gangrene.
"When I woke up in intensive care after almost three weeks unconscious, I only realised how serious my injuries were when I saw my hands and feet were black," he said.
The other five volunteers have all been released from hospital after suffering less severe symptoms.
TeGenero have said the men's reactions were "completely unexpected" and did not reflect the results obtained from the earlier laboratory studies.
Preliminary inquiries by the UK's Medicines and Healthcare products Regulatory Agency appeared to back up the firm's statement.
It found there were no obvious errors in the testing procedure but said in future first-in-man trials of similar drugs would not be authorised without expert advice.