Motion sickness

Definition
Motion sickness is a temporary response by the body to motion or movement, often resulting in nausea or vomiting.

Causes/associated factors
The inner ear and associated balance mechanisms of the body can become excessively stimulated by motion. Your inner ear and eyes detect your direction of motion, and skin receptors tell you which part of your body is touching the ground.
If there's a conflict between what your eyes see, what your body feels, and what the motion receptors in your inner ear tell you, you may develop motion sickness. For example, when you experience turbulence during an airplane ride, your body detects the motion and sends signals to your brain, even though your eyes don't see the motion. The result of the conflicting messages may be an upset stomach.

No one is immune to motion sickness, but some people seem to be more susceptible than others. Men and women are equally affected.

The most common culprits of motion sickness include:

airplanes
boats
cars
trains
amusement park rides
activities that involve extensive swinging
The risk of developing motion sickness increases with:

travel
poor ventilation
anxiety
fear
poor health
youth (Motion sickness is most common between ages 2 and 12.)
visual triggers, such as a simulator movie, waves or a shifting horizon
migraine disorders

Signs/symptoms
Symptoms of motion sickness may include:
nausea or vomiting
paleness
fatigue or a general feeling of discomfort
drowsiness or yawning
weakness
unsteadiness
increased salivation
sweating
hyperventilation
anxiety
confusion

Diagnosis
Diagnosis is based on your symptoms.

Treatment
Typically, symptoms of motion sickness develop during motion and disappear soon after the motion is stopped. They rarely last more than a few days. Because symptoms of motion sickness are not related to an illness or change in health status, treatment is rarely necessary.
If you have a history of severe motion sickness, ask your doctor about prescription medications for motion sickness. He or she may recommend a scopolamine patch. At least four hours before you travel, you tape a dime-sized disk to a hairless area behind your ear. The patch gradually releases medication through your skin and into your blood. The patch has the potential for more side effects than motion sickness pills, however, and is inappropriate for certain people with particular health conditions.

As an alternative, your doctor may recommend an oral medication such as dimenhydrinate (brand name Dramamine) or meclizine (Antivert). For severe cases of motion sickness, an intramuscular medication might be recommended, such as promethazine hydrochloride (Phenergan). As with any medication, be aware of the possible side effects for these medications. For example, promethazine hydrochloride has a sedative effect that can significantly reduce mental alertness.


Complications
Complications of motion sickness are rare, but can include hypotension (a decrease in blood pressure) or dehydration.

Pregnancy-specific information
Although motion sickness is not considered harmful to mother or baby, it may aggravate preexisting symptoms of nausea and vomiting. Do not take any motion sickness medications without consulting your doctor.

Senior-specific information
With age, the nerve receptors and other body systems that help you maintain balance gradually deteriorate. This may make older adults more vulnerable to motion sickness. Older adults are also more likely to have side effects from motion sickness medications. Consult your doctor if you have a chronic illness that could be complicated by vomiting. If you're planning to take motion sickness medication, ask your doctor if there's a risk of interaction with other drugs you may currently take.

Prevention
To help prevent motion sickness, consider the following suggestions:
If you're apprehensive about flying, try to resolve your concerns before leaving home. Some airlines offer behavior modification tips or programs for those who have motion sickness or are afraid to fly. Contact the airline or your travel agent for details.

When traveling, sit in the middle of the car, boat, train or airplane so that you experience the least amount of motion. Do not sit in a seat facing backward.

Keep the area well ventilated, if possible. Avoid strong odors, such as secondhand smoke.

Fix your vision at a 45-degree angle above the horizon. Don't look at moving objects, and avoid reading while you're in motion.

Limit your food intake, and eat small meals frequently. Avoid spicy or greasy foods.

Avoid caffeine and alcohol.

Take an over-the-counter motion sickness medication such as the antihistamine dimenhydrinate before you travel. Read the package label carefully. If you have a medical problem that could be affected by the medication, don't take it.