Motion Sickness

Motion sickness is a normal response to real, perceived, or anticipated movement. People tend to experience motion sickness on a moving boat, train, airplane, automobile, or amusement park rides. Although this condition is fairly common and only a minor nuisance for the occasional traveler, it may be incapacitating for people with an occupation that requires constant movement, such as a flight attendant, pilot, astronaut, or ship crew member. Symptoms generally consist of dizziness, fatigue, and nausea, which may progress to vomiting. Fortunately, most symptoms disappear once the journey is over.

Signs and Symptoms

The most common signs and symptoms of motion sickness include:

• Nausea
• Paleness of the skin
• Cold sweats
• Vomiting
• Dizziness
• Headache
• Increased salivation
• Fatigue

Causes

Motion sickness occurs when the body, the inner ear (a tiny structure involved in hearing and balance), and the eyes send conflicting signals to the brain. This reaction is generally provoked by a moving vehicle such as a car, boat, airplane, or space shuttle, but it may also happen on flight simulators or amusement park rides. From inside a ship's cabin, the inner ear may sense rolling motions that the eyes cannot perceive, and, conversely, the eyes may perceive movement on a "virtual reality" simulation ride that the body does not feel. Interestingly, once a person adapts to the movement and the motion stops, the symptoms may recur and cause the person to adjust all over again (although, this reaction is generally brief). In addition, even anticipating movement can cause anxiety and symptoms of motion sickness. For example, a person with a previous experience of motion sickness may become nauseous on an airplane before take-off.

Risk Factors

The following are the most common risk factors for motion sickness:

• Riding in a car, boat, airplane, or space shuttle
• Age—children between the ages of 2 and 12 are most at risk; occurrence of motion sickness declines with age (this is probably due to behavioral changes and coping strategies rather than anything inherent in the aging process)
• Susceptibility to nausea or vomiting
• Heightened level of fear or anxiety
• Exposure to unpleasant odors
• Poor ventilation
• Spending long hours at a computer screen
• Being outside of the earth's gravitational force

Diagnosis

Most people who have experienced motion sickness in the past ask their healthcare provider how to prevent another episode from occurring in the future; rarely will an individual arrive at his or her healthcare provider's office actually experiencing motion sickness. To establish a diagnosis of motion sickness, the provider will inquire about the individual's symptoms as well as the event that typically causes the condition (such as riding in a boat, flying in a plane, or driving in car). Laboratory tests are generally not necessary to establish a diagnosis of motion sickness.

Preventive Care

The following general measures may be taken to help avoid the discomfort caused by motion sickness:

• Reduce anxiety and fears, particularly through methods such as cognitive-behavioral therapy and biofeedback
• Use head rests to minimize head movements
• Maintain proper ventilation to decrease foul odors that may cause nausea
• Stay occupied to distract the mind from thinking about motion sickness; reading may worsen symptoms, however
• Particular exercises, such as tumbling or jumping on a trampoline, may desensitize an individual prior to being in a situation that causes motion sickness

Individuals who commonly experience motion sickness on a plane should take the following preventive measures:

• Avoid bulky, greasy meals and overindulgence in alcoholic beverages the night before air travel
• Eat light meals and/or snacks that are low in calories in the 24 hours before air travel
• Avoid salty foods and/or dairy products before air travel
• Sit toward the front of the aircraft or in a seat by the wing because the ride will feel smoother in these locations
• Eat foods high in carbohydrates before air travel

Individuals with a tendency toward motion sickness on a boat should take the following preventive measures:

• Passengers below the deck should keep their eyes closed and minds occupied (by engaging in conversation, for example)
• Passengers on the deck should keep their eyes fixed on the horizon or visible land

Treatment Approach

While medications may be an acceptable treatment for travelers who occasionally experience motion sickness, the goal for individuals who experience motion sickness on a regular basis or whose work is affected by their symptoms is to learn to control–and eventually prevent–these symptoms. This may be accomplished with mind/body practices, such as cognitive-behavioral therapy and biofeedback. Other alternatives to medication include homeopathy, acupuncture, ginger (Zingiber officinale), dietary adjustments, and physical therapy.

Medications

Medications for motion sickness may cause drowsiness and impair judgement and, therefore, should be avoided in pilots, astronauts, ship crew members, and individuals in any other occupation where heavy equipment is operated or where being alert is critical. The following medications are a reasonable option for infrequent travelers and others who experience motion sickness occasionally:

• Scopolamine—most commonly prescribed medication for motion sickness; must be taken before the onset of symptoms; available in patch form that is placed behind the ear 6 to 8 hours before travel; effects last up to 3 days; side effects may include dry mouth, drowsiness, blurred vision, and disorientation
• Promethazine—take 2 hours before travel; effects last between 6 and 8 hours; side effects may include drowsiness and dry mouth
• Cyclizine—most effective when taken at least 30 minutes before travel; not recommended for children younger than 6; side effects are similar to scopolamine
• Dimenhydrinate—take every 4 to 8 hours; side effects are similar to scopolamine
• Meclizine—most effective when taken 1 hour before travel; not recommended for children under 12; side effects may include drowsiness and dry mouth

Nutrition and Dietary Supplements

Generally, small frequent meals are recommended for individuals prone to motion sickness. Dietary records of a small group of novice pilots also indicate that an increase in airsickness (motion sickness from air travel) may be associated with the following:

• Foods high in sodium (salt), such as preserved meats, corn chips, and potato chips
• Foods high in thiamine (vitamin B1), such as pork, beef, eggs, and fish
• High frequency of meals consumed 24 hours before air travel
• High-calorie foods
• Foods high in protein, such as milk, cheese, and preserved meat
• Low levels of vitamins A, C, and iron (female pilots with airsickness had a low average intake of these nutrients; it is still unclear whether increased dietary intake of these nutrients would diminish symptoms of motion sickness)

Herbs

Ginger (Zingiber officinale)
Several studies suggest that ginger may be more effective than placebo in reducing symptoms associated with motion sickness. For example, in one clinical trial of 80 novice sailors (prone to motion sickness), those who took ginger (in powder form) experienced a significant reduction in vomiting and cold sweating compared to those who took placebo. Similar results were found in a study with healthy volunteers. While these results are promising, other studies suggest that ginger is not as effective as medications in reducing symptoms associated with motion sickness. In a small study of volunteers who were given ginger (fresh root and powder form), scopolamine, or placebo, those receiving the medication demonstrated a significant reduction in symptoms compared to those who received ginger. More rigorous trials are needed to confirm the effectiveness of ginger for motion sickness.

Other
Although black horehound (Ballota nigra) and peppermint (Mentha piperita) have not been scientifically studied for their use in treating motion sickness, some professional herbalists may recommend these herbs in combination to alleviate nausea associated with the condition.

Acupuncture

Some preliminary studies suggest that people with motion sickness who receive acupuncture report a significant improvement in symptoms compared to those who receive sham acupuncture (needling at points not indicated for nausea, vomiting, or motion sickness) or no acupuncture at all. Although results have been less convincing, studies also suggest that acupressure may help reduce symptoms of motion sickness in the same way as acupuncture. An acupressure practitioner works with the same points used in acupuncture, but stimulates these healing sites with finger pressure, rather than inserting fine needles.

Massage and Physical Therapy

One case study of a woman with motion sickness suggests that balance training and habituation (reducing or modifying one's response to a stimulus that causes motion sickness) may help diminish the symptoms of the condition. The use of habituation for the treatment of motion sickness is based on the theory that when an individual prone to motion sickness is repetitively exposed to the stimulus that causes motion sickness (such as driving in a car or riding on an elevator) in a controlled, supervised fashion, he or she will habituate, or become used to that stimulus. Over time, the stimulus will no longer evoke the motion sickness response and symptoms will diminish.

Homeopathy

There have been few studies examining the effectiveness of specific homeopathic remedies. A professional homeopath, however, may recommend one or more of the following treatments for motion sickness based on his or her knowledge and clinical experience. Before prescribing a remedy, homeopaths take into account a person's constitutional type. In homeopathic terms, a person's constitution is his or her physical, emotional, and intellectual makeup. An experienced homeopath assesses all of these factors when determining the most appropriate remedy for a particular individual.

• Borax — for nausea caused by downward motions, such as landing in an airplane
• Cocculus — the primary treatment for motion sickness, particularly if nausea and vertigo or other type of dizziness are present; symptoms tend to be worse in fresh air or from the smell and even thought of food
• Nux vomica — for motion sickness accompanied by headache, nausea, and ringing in the ears; this remedy is most appropriate for patients who are sensitive to light, noise, and odors
• Petroleum — for dizziness and nausea that occur when riding in a car or boat; this remedy is most appropriate for individuals who feel faint, have pale skin and cold sweats, salivate excessively, and have a hollow aching in the stomach that is relieved by eating
• Sepia — for motion sickness brought on by reading while in a moving vehicle
• Tabacum — for motion sickness with severe nausea and vomiting; this remedy is most appropriate for individuals who feel faint, have pale skin, cold sweats, and a sinking feeling in the stomach; symptoms are aggravated by tobacco smoke, but open air and closing the eyes brings relief; vomiting may also bring relief

Mind/Body Medicine

Biofeedback Training and Relaxation
In a study of 55 pilots who had to stop flying due to symptoms of motion sickness, 76% of them successfully overcame their motion sickness and were able to return to work after participating in a biofeedback training and relaxation program. Biofeedback instruments recorded skin temperature and changes in muscle tension while the pilots were exposed to a stimulus that caused motion sickness (sitting in a tilting, rotating chair). While in the chair, the pilots performed various relaxation techniques, such as deep muscle relaxation and mental imagery. Over time, the pilots habituated to the rotating chair; they no longer felt sick in the chair because they learned to relax in it.

Cognitive-Behavioral Therapy
The goal of cognitive-behavioral therapy is to alleviate the anxiety that some people experience simply thinking about movement or motion sickness. In a study of 50 pilots who occasionally experienced motion sickness, 86% of them successfully overcame their symptoms after cognitive-behavioral therapy. During cognitive-behavior therapy, individuals are exposed to a provocative stimulus (such as a tilting, rotating chair) in a slow, and controlled fashion until they experience some symptoms of motion sickness, but not until they are overwhelming. As the individual performs better and better on the rotating chair, his or her confidence builds and anxiety lessens.

Breathing Techniques
In a study of 46 people with motion sickness, those who were instructed to take slow, deep breaths had a significant reduction in symptoms of motion sickness compared to those who breathed normally or counted their breaths. Interestingly, involuntary rapid and shallow breathing often exacerbates symptoms of motion sickness. While it makes sense that slow, deliberate breathing would help reduce the anxiety associated with motion sickness, further studies are needed to determine whether breathing techniques effectively diminish the symptoms associated with the condition.

Traditional Chinese Medicine

Pingandan
One small animal study suggests that Pingandan, a Chinese herbal mixture, may significantly reduce signs of motion sickness (including defecation, urination, salivation, panting, and drowsiness). Pingandan primarily consists of:

• White atractylodes rhizoma (Rhizoma atractylodis)
• Dried tangerine peel (Pericarpium citri reticulatae)
• Round cardamom fruit (Fructus amomi rotundus)
• Hawthorn fruit (Fructus crataegi)
• Chinese eaglewood wood (Lignum aguilariae resinatum)

While individuals who have used the herbal remedy report fewer side effects than those who take scopolamine, more studies are needed to determine whether Pingandan is a safe and effective therapy for motion sickness.

Other Considerations

Pregnancy

Due to a lack of clinical evidence, there is some controversy regarding the safety of ginger taken during pregnancy. In one study of pregnant women, more than 70% reported less morning sickness while taking 250 mg of ginger 4 times per day compared to those who received placebo. Therefore, healthcare practitioners recommend limiting intake of ginger to this amount if used during pregnancy.

Prognosis and Complications

While motion sickness has no long-term complications, the condition may be devastating for those in an occupation that involves constant movement, such as a flight attendant, pilot, astronaut, or ship crew member.

The symptoms of motion sickness generally disappear quickly once the journey (such as a moving boat, train, airplane, or automobile) is over. People who travel infrequently may also become accustomed to movement during a trip lasting several days. Even those who travel often may improve from repeated exposures to the same type of experience. However, people who become anxious before a journey often experience worsened symptoms of motion sickness and tend to require more formal interventions, such as biofeedback and relaxation training.

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