I was prescibed lidex (fluocinonide) for inside the mouth is this ok?

Lichen Planus? This can be used for chronic rashes such as oral lichen planus for short period of time. After two weeks the area should be reevaluated for stopping cream, decreasing frequency of application or changing to other medication.
Yes. A thin film of Lidex (fluocinonide) gel (Fluocinonide) is sometimes used on oral lesions.