Shari Horne broke her toes a decade ago, and after surgery, “I have plates and pins and screws in my feet, and they get achy at times,” she said.

So Ms. Horne, 66, applies a salve containing cannabidiol , derived from the cannabis, or marijuana, plant. It eases the pain.

The salve didn’t help when she developed bursitis in her shoulder, but a tincture of cannabidiol mixed with T.H.C., the psychoactive ingredient in cannabis, provided relief.

Using a pipe, she also smokes “a few hits” of a cannabis brand called Blue Dream after dinner, because “I think relaxing is healthy for you.”