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Conditions InDepth: Headache

Headache is pain in the head. There are many types, such as:

They may be from:

  • Taking medicine
  • Using too much medicine to treat them
  • Infections
  • Bleeding
  • Head injury
  • Too much pressure in the head from a growth or other problem

The cause of many headaches is not known. It depends on the type of headache.

Tension Headache

This pain is from stress and muscle tightness. They may only happen once and a while because of a stressful event. They may also happen often. Some can be daily and differ in how painful they are. These headaches are when muscles in the neck, face, and scalp get tight and cause pain. The cause is not known. Stress, anxiety, depression, eyestrain, and other things may lead it.


This headache involves blood vessels, nerves, and chemicals in the brain. Eyesight problems, called auras, may come before them. You can get these headaches many times a week or once every couple of years. They may be so strong that they get in the way of normal tasks.

A trigger sets off a process that causes headaches. The exact one is often not known. The nervous system may react to the it by making electrical activity that spreads across the brain. It may cause the brain to release chemicals that help regulate pain.

Cluster Headache

This is strong pain on one side of the head that keeps coming back. It follows a cluster or pattern.

There are 2 types. Either type may change to the other:

  • Episodic—(most common) one or more times each day for many months. Then they go away and come back months or years later
  • Chronic—(less common) almost each day with, at most, one headache-free month a year

The cause is not known.

Sinus Headaches

Sinus headaches are from swelling of the sinuses. This is sinusitis. The sinuses are hollow parts of the skull. Colds and allergies cause swelling of the passages in the nose and can lead this. Allergies and viral infections cause mucus and cause tissue in the passages to swell. The passages become blocked and can't drain. Mucus that is trapped may get infected with bacteria or, rarely, fungus. The swollen tissues or infection may cause pain and pressure.


Cluster headache. EBSCO DynaMed Plus website. Available at: Updated March 20, 2018. Accessed December 19, 2018.

Headache Classification Committee of the International Headache Society (IHS) The International Classification of Headache Disorders, 3rd edition. Cephalalgia. 2018 Jan;38(1):1-211.

Headache—frequently asked questions. National Headache Foundation website. Available at: Accessed January 11, 2019.

Migraine in adults. EBSCO DynaMed Plus website. Available at: Updated November 8, 2018. Accessed December 19, 2018.

NINDS headache information page. National Institute of Neurological Disorders and Stroke website. Available at: Accessed December 19, 2018.

Tension-type headache. EBSCO DynaMed website. Available at: Updated March 20, 2018. Accessed December 19, 2018.

Last reviewed December 2018 by EBSCO Medical Review Board Rimas Lukas, MD