This medication has been prescribed to you by your specialist after much consideration. You may experience temporary burning or sting when you apply it. If the following side effects persist, inform your doctor immediately: Symptoms of allergic reactions, Rashes, Itching, Dizziness, Breathing difficulties, Swelling, Cold sores Zovirax may cause severe dizziness; hence, it is recommended that you avoid activities such as driving to prevent any mishaps. The risks increase if you regularly use recreational drugs.