I think Diclofenac is sold OTC as Voltaren gel. Kind of interesting because Diclofenac tabs are Rx only and I believe not for long term use. I don't know of any restrictions on the gel and have used it myself.

FWIW I have found Bio-Freeze Professional to be the best pain-relieving gel. It does have a strong smell of menthol but that fades and it really works on easing pain. That said, I use it for muscle soreness and not on my hands. I think Voltaren would be better on joints for arthritis pain.