HHV-6 has been associated with various clinical complications, including roseola, chronic fatigue syndrome, multiple sclerosis, encephalitis, and drug hypersensitivity. Although nearly everyone is infected with HHV-6 in childhood, only a small percentage experience reactivation of HHV-6 later in life. Moreover, many of these reactivation events never cause symptoms. However, evidence has shown that HHV-6 reactivation can occur occasionally, especially during times of stress, other illnesses, in response to acute allergic reactions or during immunosuppression. Some individuals with an undiagnosed immune deficiency may reactivate with HHV-6. We encourage you to explore the resources at right to learn more about testing, treating, and identifying HHV-6 primary infection and reactivation.