What Can Cause Headaches on Only the Left Side of My Head?

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Cluster headaches and migraines may cause intense pain on one side of the head, according to the Stanford Headache Clinic. Cluster headaches typically last less than two hours and may cause an enlarged pupil, stuffy nose and droopy eyelid. Severe migraines can persist for up to 72 hours, often causing nausea and sensitivity to light.

Cluster headaches are rare and occur in cyclical bouts called “cluster periods” before stopping for months or years, according to the Mayo Clinic. Cluster periods can last for several weeks or months, triggering throbbing or burning pain around one eye. The pain is typically one-sided and may spread from the eye to other areas of the head, face and neck. Sufferers often awaken at night from severe discomfort and experience redness, swelling and constant tearing in the affected eye.

Physicians believe activity of the hypothalamus stimulates cluster headaches, as explained by the Mayo Clinic. Once the cluster period begins, attacks occur regularly throughout the day and may cause migraine-like auras or light sensitivity. While these headaches have no known cure, doctors often use medication, hormone injections, oxygen and corticosteroids to provide relief.

According to Healthline, migraines can cause one-sided pulsating pain that leaves sufferers feeling dizzy, fatigued, nauseated or disoriented. Classic migraines are preceded by an aura, which may obstruct vision by causing blurriness, blind spots or zigzagging lines. Migraines are more prevalent in women and may occur more frequently during menstruation.

Inflamed blood vessels increase pressure around the brain, so the pain is often heavily concentrated near the temples, according to HowStuffWorks. Migraines are difficult to treat, but physicians consider various options, such as non-steroidal anti-inflammatory drugs and beta blockers, depending on the patient’s medical history.