Motion sickness is thought to be caused by conflicting signals in the inner ear, eyes, and sensory receptors.
Some people experience nausea and even vomiting when riding in an airplane, automobile, or amusement park ride. One study, published in PloS one in 2013, suggested that 3-D movies can also cause nausea.
This condition is generally called motion sickness. When riding on a boat or ship, it is commonly referred to as sea sickness - but it is the same disorder.
- There is no difference between motion sickness and sea sickness.
- Individuals and animals without a functional vestibular (balance) system are immune to motion sickness.
- Without the motion-sensing organs of the inner ear, motion sickness does not occur, suggesting that the inner ear is important in motion sickness.
- The symptoms of motion sickness include nausea, vomiting, and dizziness.
What causes motion sickness?
Motion is sensed by the brain through different pathways of the nervous system including the inner ear, the eyes, and the tissues of the body surface.
When the body is moved intentionally, for example when walking, the input from all of the pathways are coordinated by our brain.
The symptoms of motion sickness appear when the central nervous system receives conflicting messages from the sensory systems: the inner ear, eyes, skin pressure receptors, and the muscle and joint sensory receptors.
As an example, if someone is sat on a boat or in a car (not looking out of a window), their inner ears sense movement up and down, left and right, but their eyes see a static view, as if they are not moving at all. It is hypothesized that the conflict among the inputs is responsible for motion sickness.
What are the symptoms of motion sickness?
Serious symptoms include:
- short breath
Other common signs are:
- a general feeling of discomfort
- not feeling well (malaise)
Mild symptoms are categorized as:
- mild unease
Diagnosing motion sickness
Most cases of motion sickness are mild and self-treatable. Very severe cases, and those that become progressively worse, deserve the attention and care of a physician with special skill in diseases of the ear, balance (equilibrium), and nervous system.
To help diagnose motion sickness, a doctor will ask about symptoms and find out what usually causes the problem (such as riding in a boat, flying in a plane, or driving in a car). Laboratory tests are generally not necessary to diagnose motion sickness.
Remedies for motion sickness
The distressing symptoms of motion sickness usually stop when the motion causing it ceases. But this is not always true. There are people who suffer symptoms for even a few days after the trip is over. Most people who have had motion sickness in the past ask their doctor how to prevent it next time. The following remedies may help:
Looking at the horizon
One common suggestion is to simply look out of the window of the moving vehicle and to gaze toward the horizon in the direction of travel. This helps to re-orient the inner sense of balance by providing a visual reaffirmation of motion.
Keeping eyes closed and napping
In the night, or in a ship without windows, it is helpful to simply close one's eyes, or if possible, take a nap. This resolves the input conflict between the eyes and the inner ear.
Chewing gum is a simple way of reducing motion sickness.
A simple method for relieving common and mild car sickness is chewing. Chewing gum has an uncanny effectiveness for reducing car sickness in those affected.
Chewing gum, however, is not the only thing one may chew to relieve mild effects of car sickness, snacking on sweets, or just chewing in general seems to reduce adverse effects of the conflict between vision and balance.
Fresh, cool air can also relieve motion sickness slightly, although it is likely this is related to avoiding foul odors, which can worsen nausea.
Ginger has been found to reduce motion sickness. This is available in tablet form, or a fresh stem of ginger can be chewed to relieve symptoms. There is some debate over whether it is the chewing or the ginger that helps.
An acupressure practitioner works with the same points used in acupuncture, but stimulates these healing sites with finger pressure, rather than inserting fine needles. Some studies suggest that acupressure may help reduce symptoms of motion sickness in the same way as acupuncture, although the evidence is not clear.
Preventing motion sickness
Here are some important tips for preventing motion sickness:
- Always sit in a position so that the eyes can see the same motion that the body and inner ear feels.
- In a car, sit in the front seat and look at the distant scenery.
- On a boat, go up on the deck and watch the motion of the horizon.
- In an airplane, sit by the window and look outside. Also, in a plane, choose a seat over the wings where the motion is minimized.
- Do not read while traveling if experiencing motion sickness, and do not sit in a seat facing backward.
- Do not watch or talk to another traveler who is having motion sickness.
- Avoid strong odors and spicy or greasy foods immediately before and during travel.
Medical research has not yet investigated the effectiveness of popular folk remedies such as "soda crackers and 7 Up," "cola syrup over ice," or ginger products.
While home remedies are effective, medications are also a good way to prevent motion sickness and are best taken before travelling.
- Scopolamine - the most commonly prescribed medication for motion sickness. It must be taken before symptoms start. It is available as a patch that is placed behind the ear 6-8 hours before travel.
- Promethazine - should be taken 2 hours before travel. The effects last 6-8 hours. Side effects may include drowsiness and dry mouth.
- Cyclizine - is most effective when taken at least 30 minutes before travel. It is not recommended for children younger than 6, and side effects are similar to scopolamine.
- Dimenhydrinate - taken every 4-8 hours. Side effects are similar to scopolamine.
- Dimenhydrinate chewing gum - a team of experts spoke at the American Association of Pharmaceutical Scientists Annual Meeting and Exposition in 2012 on a study that showed patients can absorb the medication through the cheek.
- Meclizine (Bonine) - is most effective when taken 1 hour before travel. It is not recommended for children under 12, and side effects may include drowsiness and dry mouth.