there are no significant interactions between the medications prednisone hydroxyzine and oral decongestants such as phenylephrine or pseudoephedrine. it would be safe with these medications to take an oral decongestant but i would need to know more about you and your symptoms to tell you if it is safe for you [individually] to take a decongestant.
i am on prednisone and hydroxyzine for poison ivy. is it safe to take an oral decongestant as well?