Washington: Headaches affect hundreds of people every day - but sometimes pain in the head can indicate a more serious condition.
The most common cause of headaches are tension headaches, migraines, cluster headaches and hormone headaches.
They can also be caused by colds and flu, sleep apnoea or temporomandibular disorders, which affect the muscles and joints between the lower jaw and the skull.
Dr Clare Morrison, GP at www.MedExpress.co.uk, has set out when people should be concerned about their headache and seek medical attention.
"Headaches can vary in severity from harmless and fleeting to meaning something far more sinister. "Common types of headaches often come paired with a cold or flu or they can be tension or stress related if you're going through a particularly rough patch.
"Another common cause of headaches is sinusitis but in this case the pain will be over the forehead and it will usually be worse when bending down."
However, some headaches, Dr Morrison warned, can be a sign of something more serious. She warned they should 'not be taken lightly'.
"If you've recently endured a head injury or even just a slight knock to the head and you are experiencing a headache you could have a concussion.
"You need to look out for other symptoms paired with headaches such as confusion, double vision, nausea or even sensitivity to light or noise," she explained.
"If you have these symptoms along with your headache you should visit A&E or consult your doctor."
Dr Morrison said concussions can be accompanied by injuries to the spine or even to the brain, and should be taken seriously.
"Sudden, intense headaches which feel like you've been hit with a brick that are paired with sudden weakness or numbness, confusion and dizziness could be a sign of a stroke," she said.
"Strokes take place when the circulation of blood and oxygen is interrupted. "It's important to remember FAST (Face, Arm, Speech, Time) if you think you or someone else is suffering from a stroke."
Dr Claire also warned that sudden headaches, which are persistent could be a symptoms of a brain tumour. "Keep an eye out for other symptoms such as seizures, persistent vomiting and behavioural changes," said Dr Morrison.
"If you experience any of these along with your headache, seek medical attention immediately. It is unlikely that it will be a brain tumour but it's important to check it out anyway.
It's always imperative that you are aware of other symptoms when you're suffering with headaches that persist for more than a few hours.
"A headache is more likely to be serious if it occurs suddenly without warning and is extremely painful, if it doesn't go away or if it's triggered by physical exertion.
"If you are in doubt whatsoever speak to your doctor."