Can flexeril (cyclobenzaprine hcl) cause restless legs syndrome to worsen? is it possible to also feel it in your arms?

No: No it cannot. And no, restless legs do not involve the arms.

It cannot: The RLS and restless arms/hands syndrome are neurological, sleep movement disorders and treated with Dopamine agonists such as ropinirole (approved in rls) or pramipexole. Many practitioner use Flexeril (cyclobenzaprine hcl) as a muscle relaxant and sleep inducer as an adjunctive medication. Rec.: see sleep specialist for more information.