Common side effects: lung infection (pneumonia), cold sores (oral herpes simplex), blisters, shingles (herpes zoster), skin infection sometimes with fever and chills, low white blood cell counts shown by blood tests (neutropenia, leucopenia), high cholesterol levels, headache, dizziness, high blood pressure, mouth ulceration, stomach pain, abnormal liver function tests (increased transaminases), rash and itching and eye infection (conjunctivitis).