London-based law firm Rylands Legal is representing the claimants, which include England's World Cup-winning hooker Steve Thompson, former All Black Carl Hayman and ex-Wales captain Ryan Jones.
Many players in the group of more than 180 professional and semi-professional players have also been diagnosed with chronic traumatic encephalopathy, epilepsy, Parkinson's disease and motor neurone disease.
Rylands said the class action is being issued on behalf of the majority of those players, with the rest taking legal action soon.