What causes a one sided headache?

Migraine & Surprises: Most doctors who hear of 'one-sided' headaches (has) immediately think of migraines, which are usually on 1 side & often accompanied by 'auras' - symptoms which precede the onset of pain. Some will think of 'tension' has, but these are ill-defined. A good osteopathic hands-on exam can often elucidate the exact cause of 1-sided (or other) has and lead to specific treatment to relieve them.

Anything: Headaches can come from fatigue, sleeping too much or too little, eye strain, sleep apnea, snoring, being dehydrated, having chronic sinusitis or allergies, too much caffeine or over the counter headache medication, high blood pressure or something more serious like a tumor. See your doctor and get checked.