What is a thunderclap headache?

When you experience a dor de cabeça, deciding whether it's worth a trip to the doctors can be a bit of a headache in itself. One of the most important indicators is how severe and incapacitating your headache is.

A thunderclap headache comes on very suddenly and is very painful.

Dr Hana Patel, GP and mental health coach, explains why you should see a doctor if you think you have one:

"This may be a sign of a life-threatening headache, and should be investigated - especially when the headache develops over a few minutes and in people with no previous history of having headaches."

For some people who have thunderclap headaches there's no obvious cause and the people who experience them are healthy. However, Patel explains that in other cases they are caused by serious conditions involving bleeding in the brain. For this reason, they should be considered a medical emergency.

The most important of these conditions is a hemorragia subaracnoide - an uncommon life-threatening form of derrame where bleeding occurs between the brain and its surrounding membrane.

The second most common dangerous cause of thunderclap headaches are reversible cerebral vasoconstriction syndromes. In these rare group of conditions, the blood vessels in the brain suddenly tighten. Again, these should be seen as a medical emergency.

This is a sudden and severe headache that lives up to its name - striking like a clap of thunder in your head or neck. People often say it feels like they have been suddenly punched in the back of the head. This can happen after certain triggers - such as sexual activity - or have no trigger at all.

Thunderclap headaches may or may not also be accompanied by other warning signs, including:

• Náusea ou vômito.

• Feeling drowsy or fainting.

• Febre.

• Convulsões.

• The pain extending down to your neck.

• Muddled thinking.

• Slurred speech as if you were drunk.

• Dificuldade em andar em linha reta.

• Having limb weakness.

• Feeling like the room is spinning.

How long does a thunderclap headache last?

Thunderclap headaches tend to reach their most painful point within 30 to 60 seconds of starting, but this doesn't mean they're short-lived. It's common for these headaches to take around an hour to disappear after peaking, and in some cases they can last for many hours or even for a week or more.