By definition, chronic daily headaches must occur 15 days or more a month, for at least three months. And to be considered true (primary) chronic daily headaches, they must also not be the result of another condition.

Chronic daily headaches are classified by how long they last — more than four hours or less than four hours. The longer lasting headaches are more common and addressed here. They're divided into four types:

  • Chronic migraine
  • Chronic tension-type headache
  • New daily persistent headache
  • Hemicrania continua

Chronic migraine

These headaches evolve from episodic migraine without aura. To be diagnosed with chronic migraine, you must have headaches — migraine, tension-type or both — 15 days or more a month, for at least three months. In addition, on eight or more days a month for at least three months, you must experience the following symptoms.

Your headaches have at least two of the following characteristics:

  • Affect only one side of your head
  • Cause a pulsating, throbbing sensation
  • Cause moderate to severe pain
  • Are aggravated by routine physical activity

And they cause at least one of the following:

  • Nausea, vomiting or both
  • Sensitivity to light and sound

Alternatively, if your headaches respond to triptan medications or ergot medications taken in anticipation of these symptoms — on eight or more days a month, for at least three months — they're also considered chronic migraines.

Chronic tension-type headache

These headaches evolve from episodic tension-type headaches. They may last hours or be constant.

Chronic tension-type headaches have at least two of the following characteristics:

  • Hurt on both sides of your head
  • Cause mild to moderate pain
  • Cause pain that feels pressing or tightening, but not pulsating
  • Aren't aggravated by routine physical activity

In addition, they cause no more than one of the following:

  • Sensitivity to light or sound
  • Nausea (mild only)

New daily persistent headache

These headaches become constant within a few days of the moment you have your first headache.

New daily persistent headaches have at least two of the following characteristics:

  • Hurt on both sides of your head
  • Cause pain that feels like pressing or tightening, but not pulsating
  • Cause mild to moderate pain
  • Aren't aggravated by routine physical activity

In addition, they cause no more than one of the following:

  • Sensitivity to light or sound
  • Nausea (mild only)

Hemicrania continua

These headaches cause pain on only one side of your head that doesn't shift sides. They also:

  • Are daily and continuous with no pain-free periods
  • Cause moderate pain but with spikes of severe pain
  • Respond to the prescription pain reliever indomethacin (Indocin)
  • May sometimes become severe with development of migraine-like symptoms

In addition, hemicrania continua headaches cause at least one of the following:

  • Tearing or redness of the eye on the affected side
  • Nasal congestion or runny nose
  • Drooping of the eyelid or constriction of the pupil

When to see a doctor

Occasional headaches are common. But it's important to take headaches seriously. Consult your doctor if:

  • You usually have two or more headaches a week.
  • You take a pain reliever for your headaches every day or almost every day.
  • You need more than the recommended dose of over-the-counter pain remedies to relieve your headaches.
  • Your headache pattern changes.
  • Your headaches are getting worse.

Seek prompt medical care if your headache:

  • Is sudden and severe
  • Accompanies a fever, stiff neck, confusion, seizure, double vision, weakness, numbness or difficulty speaking
  • Follows a head injury
  • Gets worse despite rest and pain medication
Mar. 15, 2012