While headache seems to be a common problem, it can also result in disability and even death, if not promptly recognised and treated on time, said Sudhir Kumar, a Hyderabad-based neurologist.

The doctor, from Apollo Hospital in Hyderabad, in a post on X.com, said that headaches are usually not serious, and commonly are migraine and tension-type headaches.

These present no serious complications and are easily and often effectively treatable.

"However, not all causes of headache are benign. Some of the conditions that cause headaches are serious and may result in disability and even death if not promptly recognised and treated on time," said Sudhir.

The doctor noted that the most severe headache is due to "subarachnoid haemorrhage", which causes life-threatening bleeding in the brain.

This severe headache recently affected motivational speaker Jaggi Vasudev, who suffered from it for several weeks. He, later, underwent emergency surgery to relieve the bleeding in the skull.

"Headache that often wakes up a person from sleep, or is worse in mornings on waking up, or that results in vomiting, double vision, etc, could be suggestive of brain tumour," said Sudhir. He added that headaches coming along with weakness of the arm or leg could indicate a risk of "stroke".

Further, the expert said that headache linked with fever, and reduced alertness "could be meningitis (brain fever)", and that which comes along with fever and seizures (fits) is "suggestive of encephalitis (brain fever)".

"New-onset headache in a person aged above 50; headache lasting for more than 72 hours; a headache that is not responding to pain-relief medications," could also be "red flags", requiring attention, Sudhir said.

Recent changes in headache frequency, severity, or character may also be a risk factor that warrants further investigation.

"If you notice any of the above "red flags" associated with headaches, it is better to consult a neurologist and undergo a brain scan (CT or MRI) and/or other investigations to determine the underlying cause, so that the appropriate treatment can be started," Sudhir said.

"Early recognition and prompt initiation of appropriate treatment can be life-saving in these conditions," he added.