Motion sickness is the body's response to conflicting messages about motion that are sent to the brain. The conflict is between what the eyes see and what the body senses.
What is going on in the body?
Information about motion and how the body is moving is obtained through the eyes and two places within the inner ear. This information is then sent to the brain so that the body can respond by coordinating muscles and maintaining balance. Information from these parts may indicate that a person is walking, doing hand stands, or even cartwheels. Other information is about the surface under a person or the area surrounding them. For instance, a person on top of a surfboard may not be moving but the surfboard and the water under the person is moving. Signals about the movement of the water and the surfboard are sent to the brain. These signals give information that helps the person to balance on the surfboard. When the brain receives one message from the eyes and another message from the inner ears, a person may feel the symptoms of motion sickness.
Different factors, such as speed, may cause motion sickness. Slow movement up and down while accelerating forward is more likely to stimulate motion sickness rather than fast movement up and down. For instance, more people feel motion sickness while riding a camel than riding a horse. Motion sickness is often reported while traveling aboard ships, but not while windsurfing.
Conflicting information regarding motion can be seen when a person is traveling on a ship looking out at the waves in the ocean. The inner ear perceives the up and down motion of the body riding on the ship, while the eyes perceive the random forward movement of the waves.
Another type of conflicting message occurs when the inner ear perceives movement while the eyes detect no movement. This can occur while standing or sitting still inside a moving ship or vehicle with no windows to visually explain the movement. It can also happen when a person is trying to read when traveling in a car. The inner ear perceives the movement of the car but the eyes detect no movement.
What are the causes and risks of the condition?
While there are usually no real risks associated with motion sickness, prolonged nausea and vomiting without eating or drinking can lead to dehydration and weakness. In this weakened condition a person may injure himself or herself due to a fall or other incident.
What can be done to prevent the condition?
Any person with a healthy inner ear system is susceptible to motion sickness. Some things make a person more susceptible and less able to adapt. This is likely due to the maturity or decline in function of the inner ear system. For instance, children between the ages of 4 and 10 are more susceptible to motion sickness. In contrast, elderly people tend to be more resistant to motion sickness. Women of any age, but especially during menstruation or pregnancy seem to be more vulnerable as well.
Measures to reduce or prevent motion sickness include:
- eating a small light meal no less than 3 hours before exposure
- focusing on a stable horizon or distant focal point while in motion
- limiting head movements
- staying centrally located while traveling on a boat or plane
- sitting up front or driving when traveling in a motor vehicle
- avoiding reading or needlework when traveling in a motor vehicle
- staying in a well ventilated area
How is the condition diagnosed?
There is no test to diagnose motion sickness. Instead, it is usually diagnosed after a person has had motion sickness and asked his or her healthcare professional for help. The professional may discuss past episodes of motion sickness with the person in order to find ways to prevent it in the future.
Long Term Effects
What are the long-term effects of the condition?
The lingering effects of motion sickness will depend on how long a person is exposed to the stimulus and how severe the symptoms are. Once the stimulus causing motion sickness is removed, the actual symptoms will usually stop within a few minutes to a couple of hours. No long-term effects can be expected.
What are the risks to others?
Motion sickness is not contagious.
What are the treatments for the condition?
Treating motion sickness focuses on easing any nausea and vomiting. These symptoms usually are caused by chemicals that are released in the body and stimulate the vomiting center in the brain. The goal of medication is to block the effects of these chemicals on the brain. Prescription medications are available in the form of a patch worn behind the ear. This patch is not recommended for children.
Over-the-counter drugs that do not require a prescription are also available to combat motion sickness. These medications are antihistamines, such as diphenhydramine (i.e., Benadryl). The most common home remedy for motion sickness is ginger, although there is no scientific evidence that it is effective.
What are the side effects of the treatments?
The most common side effects of both the patch and over-the-counter antihistamines is dry mouth, blurry vision, and drowsiness. A healthcare professional may prescribe other medications that can offset these side effects.
What happens after treatment for the condition?
Rest and relaxation is encouraged after treatment.
How is the condition monitored?
Monitoring of the person experiencing motion sickness is only necessary to provide appropriate comfort and safety measures. These may include medication, fresh air, fluids, and small meals. Motion sickness is different for every person. The intensity of symptoms depends upon the person, along with the amount of time and the source of stimulus causing the motion sickness.
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Motion sickness remedies - ginger to scopolamine. UC Berkeley Wellness Letter. 1999; 6-7