Many viral infections can either directly or indirectly cause headache.
The headache related to these viral infections appears to be related to the fever, the body's production of interferon, and other elements of the immune system in combating the viral infection. Headache may also be associated with those viral infections that affect the upper respiratory tract, such as the common cold virus, the Rhinovirus. This particular infection may produce intense congestion in the nasal passages, which at times causes a blockage of the sinus drainage passages, and can also cause headaches. Headache may also result from viral infections that specifically attack the brain and its coverings, such as encephalitis and meningitis. Chronic viral infections have been identified as a cause of headache and other conditions, such as the chronic fatigue syndrome.