Novichok victim Charlie Rowley fears the poison will eventually kill him and believes he could be dead within a decade.
Mr Rowley said he is “terrified” about the future, and is struggling with his eyesight and mobility.
The 45-year-old was exposed to the same nerve agent used in Salisbury to attack ex-spy Sergei Skripal and his daughter Yulia in March.
Mr Rowley and his partner Dawn Sturgess, 44, fell ill in Amesbury months after the Skripal incident, and Ms Sturgess died in hospital in July.
Britain has accused Russia of carrying out the poisoning of the Skripals, which the pair survived.
Russia has also been blamed for the death of Ms Sturgess and the poisoning of Mr Rowley, who are believed to have come into contact with Novichok discarded by the Skripals’ attackers.
Mr Rowley, who was in hospital being treated for meningitis, told the Sunday Mirror: “I may be out of hospital but I don’t feel safe. I’m terrified about the future.
“Doctors simply don’t know what the long-term effects could be.
“The worst thing has been the fear over my sight. I’m struggling to see properly and to walk.
“I’m one of only a handful in the world to have survived Novichok, so it’s untrod territory. I feel like a guinea pig. I don’t know what’s going to happen from one day to the next.”
He added: “I’m still worried the Novichok could kill me if I get any sort of virus again – it’s on my mind all the time. I’m dreading getting a cold.
“When I got out of hospital the first time I was pleased. But it may have been too soon because a few weeks later I was back – blind and unable to use my left arm with meningitis.
“I remember losing all balance and suffering tunnel vision. Doctors told me I’d suffered numerous strokes and I needed heart treatment and a pacemaker. It’s all to do with the Novichok.”
Mr Rowley told the newspaper he has felt suicidal, and said he has had no support.
“The system is flawed. I need counselling. If the authorities offered me help I would take it. I feel let down,” he said.
Mr Rowley added: “I don’t think I’ll be alive in 10 years. It has been horrendous.”
Police have said they do not believe that Mr Rowley or his partner were deliberately targeted, rather that they were affected because of the “recklessness in which such a toxic nerve agent was disposed of”.