According to recent data, American doctors routinely misdiagnose migraines as “sinus headaches”—as if pressure from clogged sinuses is causing the pain. Then they prescribe antibiotics, which do nothing, notes Mark Green, director of the Columbia University Headache Center in New York City. “Medically,” he says, “there is no such thing” as a sinus headache.

Migraines are an inherited form of recurring headaches, in some cases accompanied by auras: perceived noises or flashing lights. Patients who go untreated for too long may incur structural changes in their brains, so they should insist on proper therapy, which may involve drugs similar to those used by epileptics.

Some confusion in diagnosis occurs because neurons in the brain stem can activate the sinuses during a migraine, causing them to secrete a clear fluid. Yet this discharge differs from the cloudy fluid produced by a sinus infection. Taking unneeded antibiotics can kill harmless bacteria, helping antibiotic-resistant strains to flourish. Green advises doctors to consider migraines more seriously and to look for eye tearing and clear nasal secretions as symptoms.