A thunderclap headache is a severe headache that, as suggested by the name, strikes suddenly, like a clap of thunder. It typically reaches its peak severity within one minute of the onset and fades gradually over the next few hours. Thunderclap headaches are considered a medical emergency because they act as a warning sign for serious medical conditions. Do I have a thunderclap headache or a migraine? The most noticeable difference between migraine and thunderclap headaches is the intensity of...