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Pronunciations cyclizine dimenhydrinate diphenhydramine meclizine promethazine

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). Motion sickness commonly occurs during boat travel, when the boat rolls and rocks. It may also occur in a moving car, amusement park rides, or other moving vehicles. Some people are more susceptible than others. 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, vertigo, headache, and fatigue usually develop. The face may become pale, and the person may break into a cold sweat. Vomiting often occurs. Other symptoms may include increased saliva production (often as a prelude to vomiting) 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:

• Using visual fixation (for example, watching the distant horizon on a rocking boat; sitting in the driver's seat and looking ahead)
• Choosing a seat where motion is felt least (such as the front seat of a car, a seat over the wings in an airplane, or the forward or middle cabin or upper deck of a ship)
• Keeping the head and body as still as possible
• Sitting face forward and in a reclining position
• Not reading
• Getting fresh air by opening a window, opening an air vent, or going to a ship's top deck
• Not drinking alcoholic beverages and not smoking (both can aggravate nausea)
• Eating small amounts of low-fat, starchy foods and not eating strong-smelling or strong-tasting foods
• Avoiding food and drink on short airplane trips, especially on small airplanes

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. These drugs include cyclizine Some Trade Names
MARAZINE
, dimenhydrinate Some Trade Names
DRAMAMINE
, diphenhydramine Some Trade Names
BENADRYL
NYTOL
SOMINEX
, meclizine Some Trade Names
ANTIVERT
BONINE
, promethazine Some Trade Names
PHENERGAN
, and scopolamine Some Trade Names
ISOPTO HYOSCINE
(as a patch or as tablets). All of these drugs cause drowsiness, but they may cause agitation in infants and very young children and should not be given to them except under a doctor's supervision. Anyone who performs an activity that requires alertness or concentration, including driving, should not take a motion sickness drug. A motion sickness drug should not be taken with alcohol, sleep aids, sedatives, or other drugs that also cause drowsiness and decrease alertness.

If motion sickness develops, eating soda crackers or drinking carbonated soda, such as ginger ale, may help. Because of the nausea, scopolamine Some Trade Names
ISOPTO HYOSCINE
, the only drug for motion sickness that 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.

Last full review/revision October 2007 by Michael Jacewicz, MD