A headache of abrupt onset is characteristic of a sudden event such as a subarachnoid haemorrhage. The patient may liken the pain to being being hit on the head.
Some patients describe the development of a sudden headache at the moment of sexual climax - coitus cephalgia.
A headache that is rapidly developing and comes on over a day or two may be migrainous but may also be seen in meningitis.
Other differentials include thunderclap headache and acute neck pain.
Last reviewed 01/2018