India, Sept. 25 -- A headache can happen unexpectedly and be very painful. But if the pain comes on suddenly, reaches its peak within a minute, and is accompanied by nausea or vomiting, it needs urgent medical attention, becoming an emergency. This is known as a thunderclap headache.ALSO READ: Shoes suddenly feeling tight? Cardiologist shares signs of edema to watch for

Dr Vipul Gupta, director of neurointerventional surgery at Sir H.N. Reliance Foundation Hospital, Mumbai, explained what causes it, how it differs from a migraine, and why it should never be ignored.

The surgeon elaborated on what sets a thunderclap headache apart: how quickly the pain reaches its peak and how patients describe the headache.

"Thunderclap headaches are s...