Learn about the potential side effects of prednisone. of normal skin color; red face; reddish purple lines on the arms, face, legs, trunk, or groin. Prednisone Side Effects by Likelihood and Severity Dry Skin; High Blood Sugar; Irregular Periods; Puffy Face From Water Retention; Small Red Skin Lesions. Prednisone is a steroid given orally (by mouth) to treat cancer. Signs of allergic reaction to this drug may be swelling of the face, feeling like your tongue or.