Pretty much everybody gets headaches sometimes, and the vast majority of them are nothing to worry about. But there are sometimes what we call red flags, and these are what you should look out for and always seek medical help for. The one everyone knows as a red flag is a severe headache that’s accompanied by not liking the light, neck stiffness, and fever, particularly if you have a rash which doesn’t fade when you press a glass against it.

But you should also seek emergency medical help if you have a worsening headache when you’ve had a head injury in the last 24 hours if you have what we call a first and worst headache, the first time you’ve ever had that headache and the worst headache you’ve ever had. People sometimes describe it as a thunderclap headache, like being hit on the back of the head. If you get a headache that comes on for the first time when you cough or sneeze, or if you have a headache that is associated with feeling confused, with weakness down one side, or with problems with slurring of your speech or not being able to find your words.

You should also seek urgent help, although not necessarily straight away. If you have a headache, which you’ve never had a headache like this before. You get it for the first time over the age of 50, especially if it’s on one side if you have a headache that doesn’t get better when you lie down in the quiet, or which wakes you from sleep, or if you have a history of cancer which might spread, or you’ve been taking steroids at high doses.