The 76-year-old actor has revealed he uses an ointment, spray and edible marijuana medicine in order to combat the symptoms of his arthritis.
Sir Patrick explained: "Two years ago, in Los Angeles, I was examined by a doctor and given a note which gave me legal permission to purchase, from a registered outlet, cannabis-based products, which I was advised might help the ortho-arthritis in both my hands.
"This, it would seem, is a genetically-based condition. My mother had badly distorted and painful hands.
"I purchased an ointment, spray and edibles. The ointment, while providing some relief from the discomfort, was too greasy to use during daytime and so I only use it at night.
"It helps with sleep as the pain was reduced. The spray, however, is much more usable and I spray my fingers and particularly my thumb joints several times a day."
The 'Logan' actor made the confession in support of a research initiative by Oxford University, which is seeking to uncover the benefits of cannabis-based medicines.
Explaining how he uses the medicine, Sir Patrick said: "The spray very quickly evaporates and leaves my hands quite dry, though with a slight burning or tingling sensation, which is not unpleasant.
"I believe that the ointment and spray have significantly reduced the stiffness and pain in my hands. I can make fists, which was not the case before I began this treatment."
Sir Patrick hopes the research will serve to remove the prejudice that surrounds marijuana use.
He said, according to the Daily Mail newspaper: "This is an important step forward for Britain in a field of research that has for too long been held back by prejudice, fear and ignorance. I believe this programme of research might result in benefits for people like myself as well as millions of others."