The disease is somewhat more serious in persons who have a suppressed immune system, pregnant women (where it can cause birth defects), and adults who did not have the disease as a child. In these patients, anti-viral medications are advised to prevent complications. However, they are not recommended in normal childhood cases. Shingles is a complication of a second infection of varicella in older persons who have the disease. It usually causes fever, fatigue, and minor skin irritation for about 7–10 days before resolving itself.