If we make a fatty ointment in a jar, with a corticoid, should an anti-oxidance be added if we want to make the jar more than 1 month sustainable?

I note that most of the ointments with corticosteroids in the TMF are given a shelf life of 2 months. This seems to me to be an acceptable and viable term. Only when you would use fats of vegetable or animal origin (lard) is an antixidans necessary.