Motion sickness

Motion sickness occurs due to a difference between actual and expected motion. Symptoms commonly include nausea, vomiting, cold sweat, headache, dizziness, tiredness, loss of appetite, and increased salivation. Complications may rarely include dehydration, electrolyte problems, or a lower esophageal tear. The cause of motion sickness is either real or perceived motion. This may include car travel, air travel, sea travel, space travel, or reality simulation. Risk factors include pregnancy, migraines, and Ménière's disease. The diagnosis is based on symptoms. Treatment may include behavioral measures or medications. Behavioral measures include keeping the head still and focusing on the horizon. Three types of medications are useful: antimuscarinics such as scopolamine, H1 antihistamines such as dimenhydrinate, and amphetamines such as dexamphetamine. Side effects, however, may limit the use of medications. A number of medications used for nausea (antiemetics) such as ondansetron are not effective for motion sickness. Many people can be affected with sufficient motion and nearly everyone will experience motion sickness at least once in their lifetime. Susceptibility, however, is variable, with about one-third of the population being susceptible while other people can be affected only under very extreme conditions. Women can be more easily affected than men. Motion sickness has been described since at least the time of Homer (c. eighth century BC).