Is salsalate a prescription drug?

Yes: Salsalate is an alternative to Aspirin generally used for treatment of arthritis. It is useful when a patient cannot take regular Aspirin due to gastrointestinal problems. Regular Aspirin can cause gastrointestinal bleeding in certain people especially those with a history of ulcers. Salsalate is much less likely to cause such problems (about the same bleeding rate as placebo).

Yes it is: only available with prescription!