If you have a history of migraine, you should contact your doctor if you develop headaches that differ from your usual headache or other migraine symptoms. Examples include:
Headaches that get worse over time
New onset of migraine in a person over age 40
Severe headaches that start suddenly (often known as thunderclap headaches)
Headaches that worsen with exercise, sexual intercourse, coughing or sneezing
Headaches with unusual symptoms such as passing out, loss of vision, or difficulty walking or speaking
Headaches that start after a head injury
In addition, you may want to see your health care professional if you have headaches that do not get better with over-the-counter medications; severe headaches that interrupt work or the enjoyment of daily activities; or daily headaches.