The AARP says if you’re suddenly experiencing a headache “unlike any you’ve had before,” then you should call emergency services or get someone to take you to the hospital. You may be suffering a brain aneurysm, which can often be fatal.
There are other conditions that can cause a sudden intense headache, such as meningitis and temporal arteritis (which can actually lead to vision loss), notes the source. Shingles may also be the culprit. The “good” news is that it probably isn’t a brain tumor, which actually starts as a dull headache and builds over weeks or months, it adds.