My doctor prescribes allegra and I get fexofenadine HCl doc prescribes ativan (lorazepam). Are generics ok to use?

Most times, yes. In most cases, a generic preparation will have the same effect as a trade name drug - ex. The generic Lorazepam vs branded ativan (lorazepam). Sometimes, however, the generic may not be as potent as the branded drug; or one might have a side-effect from the generic which wasn't experienced from the branded drug.

Related Questions

My doctor prescribes allegra and I get fexofenadine. Doc prescribes ativan, I get lorazepam - why generics?

Cost. Generics are usually cheaper because of the lack of marketing overhead, and are frequently made by the brand name companies.
Cost. Generics must be just as good, period. Buy a nice sweater with the money you saved.
Ativan (lorazepam) Price and fact that many insurance companies request trying generic. As long as they work for u, it is ok.