An imbalance of fluid in the inner ear.

Symptoms: Sudden attacks of vertigo that can lead to severe nausea and sweating. Often they are preceded by a feeling of pressure in one or both ears, a loss of hearing, or the perception of odd noises. Episodes can last two to four hours.

The fix: Limiting sodium to 1,500 milligrams a day to ease fluid retention and avoiding caffeine, alcohol, and tobacco help 80 to 90 percent of patients. Diuretic drugs can also ease fluid pressure, as can the handheld Meniett device, which delivers pulses that disperse fluid. Steroid or antibiotic injections can help stubborn cases.