Motion sickness (also known as car, sea, train, or air sickness) involves a group of symptoms, particularly nausea, caused by movement during travel.
Motion sickness occurs when the parts of the inner ear that help control balance (including the semicircular canals) are stimulated too much, as can occur when motion is excessive. It can also occur when the brain receives contradictory information from its motion sensors—the eyes, the semicircular canals, and the muscle sensors (nerve endings in muscles and joints that provide information about body position). For example, motion sickness commonly occurs during boat travel, when the boat rolls and rocks while the person looks at something that does not move, such as a wall. In this case, the rolling and rocking do not match the lack of movement in the wall. The brain can also receive contradictory information if a person sees something moving excessively despite the person being still. This type of contradictory information may be received when, for example, a person watches a movie taken with a camera that shakes or plays a video game. Motion sickness may also occur in a moving car or other vehicles or on playground or amusement park rides. Space travelers can also be affected.
Some people are more susceptible than others. Motion sickness is more common among women and children between 2 and 12 years, as well as in people susceptible to migraines, who have labyrinthitis (a disorder affecting the inner ear), or who are pregnant or use hormonal contraceptives. Fear, anxiety, and poor ventilation increase the likelihood of experiencing motion sickness.
Symptoms and Diagnosis
Symptoms may begin relatively suddenly. Nausea, a vague feeling of abdominal discomfort, dizziness, headache, and fatigue usually develop. The face may become pale, and the person may be unable to concentrate, may feel sleepy, or may break into a cold sweat. Vomiting often occurs. Other symptoms may include increased saliva production (often as a prelude to vomiting), swallowing excessive air (aerophagia), and abnormally rapid, deep breathing (hyperventilation). Hyperventilation may cause faintness. Nausea and vomiting make the person feel weak. Prolonged vomiting can lead to low blood pressure and dehydration. However, symptoms tend to gradually subside when the motion stops or the person leaves the vehicle. Also, people who are on long trips, as on a ship, usually adapt to the motion (helped by the stabilizers used in modern ships to minimize motion) and gradually recover.
Motion sickness is diagnosed based on a description of the symptoms and the circumstances in which they occur.
Prevention and Treatment
Measures include the following:
Before traveling, people who are susceptible to motion sickness can ask their doctor to recommend an over-the-counter drug or prescribe a drug to prevent the disorder. People should take these drugs before motion sickness starts because these measures tend to be less effective after symptoms begin. Drugs include cyclizine, dimenhydrinate, diphenhydramine, meclizine, promethazine (sometimes combined with caffeine), and scopolamine (as a patch or as tablets). All of these drugs cause drowsiness. Because they may cause agitation in infants and very young children, these drugs should not be given to them except under a doctor's supervision. People doing activities that require alertness or concentration (including driving) should not take these drugs. These drugs also should not be taken with alcohol, sleep aids, sedatives, or other drugs that also cause drowsiness and decrease alertness.
If motion sickness develops, limiting food and drink to bland foods (such as soda crackers) and carbonated beverages (such as ginger ale) may help keep symptoms from worsening. Because of the nausea, scopolamine, which is given through a skin patch, is often more useful than other drugs, which are taken by mouth. Drugs can also be given by injection if necessary. If vomiting develops, an antiemetic drug, such as ondansetron or granisetron, can be given, sometimes by injection or as a skin patch.
Adaptation can be a particularly useful strategy for treating motion sickness. The more often a person is exposed to the stimulus, the less likely the stimulus is to cause a response. However, the reaction is specific to the stimulus, so a person who becomes accustomed to the motion of a large ship may still experience motion sickness in a small boat.
Some people try alternative therapies, such as wearing wristbands that apply acupressure or electrical stimulation or taking ginger, to prevent or treat motion sickness. However, these methods have not been proven effective.
Last full review/revision January 2014 by Adedamola A. Ogunniyi, MD