Philip Stevens, from Ringwood, Hampshire, was diagnosed with multiple sclerosis in 1995 and in 2015 his health deteriorated, forcing him to stop working.

In July 2017 he developed a tremor in his left leg which would keep him awake at night and he was diagnosed with restless leg syndrome by his GP, who prescribed him with Ropinirole – a dopamine antagonist medication.

Leigh Day solicitors, which represented Mr Stevens, said the GP did not warn him of possible side-effects including an impulse control disorder which can cause uncontrollable gambling or shopping.

A spokeswoman said Mr Stevens, who has two children and three stepchildren, had previously enjoyed going to horse races but was “careful and intentional” with the bets he made.

But after taking the medication his gambling “spiralled out of control”, and he regularly made bets on his smartphone and even woke up in the middle of the night to place bets.

The spokeswoman said: “Over the four years that Philip took Ropinirole, he spent thousands of pounds on online gambling websites.

“His gambling became compulsive, and he was betting on anything he could and stopped caring about winning altogether. He did not feel in control of his actions.”

She added Mr Stevens also started shopping “compulsively” for clothes that he hid from his wife, and he also felt compelled to go on three-day fishing trips every week and became “obsessed” with purchasing excessive amounts of fishing equipment.

In October 2021, Mr Stevens, who previously worked as a rent officer for a local authority, was reviewed by a neurologist and stopped taking the medication but he claimed he was not given advice on how to stop taking it gradually.

The spokeswoman said his compulsive behaviours stopped but he started to suffer from withdrawal symptoms including exhaustion, hallucinations and paranoia, such as asking his children to take DNA tests because he was convinced they were not his.

This led to feelings of depression and he was referred to the local mental health crisis team in August 2022.

Mr Stevens said: “The things that I once enjoyed that became obsessions, such as fishing and horse racing, are now joyless because with each one a sense of guilt overcomes me.

“I am not the same person as I was pre-Ropinirole. The withdrawal symptoms along with the shame of my compulsive behaviour has mentally drained me and left me very withdrawn.

“On a positive level, my marriage has survived and I am beginning to look forward more than backwards, and maybe one day I will believe that what happened to me was not my fault.”

Medical negligence solicitor Angharad Vaughan said: “I am pleased that we were able to secure this settlement for Philip.

“It is shocking that it took so long for a medical professional to flag the potential side-effects and withdrawal symptoms from taking Ropinirole.

“We hope that important lessons will be learned from this case to ensure that, in future, patients receive all the information they need about the potential side effects of such drugs.”

The Leigh Day spokeswoman said the financial settlement was agreed without the GP accepting liability.