What symptom is the hallmark of viral meningitis?

Severe headache is a hallmark symptom of viral meningitis and is often one of the most prominent clinical features observed in affected individuals. In viral meningitis, this headache can be intense and may be accompanied by other symptoms, but the severity distinguishes it from headaches due to other less serious illnesses.

Headache occurs due to inflammation of the protective membranes covering the brain and spinal cord, known as the meninges. This inflammation can irritate the surrounding tissues and contribute to the sensation of pain. Patients commonly describe this headache as different from their usual headaches, sometimes noting that it feels more severe or persistent.

While fever, nausea and vomiting, and a stiff neck are also associated symptoms and can be present in cases of viral meningitis, they do not represent the singular hallmark symptom. Fever is a common response to infection; nausea and vomiting can occur with many different illnesses, and a stiff neck is more specific to meningitis in general. Hence, while these symptoms may appear in a patient with viral meningitis, the severe headache stands out as the most distinguishing feature.