Motion sickness is the feeling you get when the motion you sense with your inner ear is different from the motion you visualize. It is a common condition that occurs in some people who travel by car, train, airplane or boat. Many people suffer from this condition if they ride on a roller coaster or other similar amusement park rides. Motion sickness progresses from a feeling of uneasiness to sweating and/or dizziness. This is usually quickly followed by nausea and/or vomiting.
Who is at risk for motion sickness?
Although pregnant women and children are more susceptible to motion sickness, almost anyone that is traveling is at risk for motion sickness. For those people who travel on boats, seasickness can be considered a form of motion sickness. Other risk factors include the person’s fear or anxiety about traveling, the mode of travel, poor ventilation in the traveling vehicle, and the inability to see out of a window to aid orientation.
What are causes of motion sickness?
Motion sickness is caused by the mixed signals sent to the brain by the eyes and the inner ear (semicircular canals). If you cannot see the motion your body’s feeling, or conversely, if you cannot feel the motion your eyes see, then it is likely that the brain will get mixed signals and the person will develop some aspect or symptom of motion sickness.
What are the signs and symptoms of motion sickness?
The signs and symptoms of motion sickness usually begin with a feeling of uneasiness followed by cold sweats and dizziness. Some people may exhibit pale skin and increased saliva production along with headache and fatigue. Nausea and vomiting usually occur after these initial symptoms.
When should I call a doctor for motion sickness?
In most cases, a doctor doesn’t need to be called for motion sickness unless the person starts to develop dehydration from persistent and intractable vomiting. In most people, once the motion has stopped, the symptoms slowly decrease and then disappear.
How is motion sickness diagnosed?
In general, motion sickness is diagnosed by the patient’s history and physical examination. The individual’s description of symptoms and the context in which they occur is most often sufficient to make the diagnosis. Laboratory testing is not generally required.
What is the treatment for motion sickness?
Treatment for motion sickness can consist of medical treatment, simple changes in the environment (for example, sitting by the open window of a car), over-the-counter (OTC) medications and for some people, home remedies may be effective. In addition, some patients respond well to biofeedback training and relaxation techniques
Medication SummaryAnticholinergic AgentsAntihistaminesSympathomimeticsAmphetaminesCaffeineOther Medications
The goal of pharmacological therapy is to prevent motion sickness, or relieve the symptoms of motion sickness, such as nausea.
Scopolamine, an anticholinergic, is used for the prevention of motion sickness and for acute treatment. Scopolamine’s effectiveness is likely due to its central anticholinergic properties.
Common adverse effects can include dry mouth/nose/throat, drowsiness, loss of visual accommodation, and sensitivity to bright light. Less common adverse effects include palpitations, urinary retention, bloating, constipation, headache, and confusion.
Scopolamine, which is most commonly prescribed as a transdermal patch, should be administered at least 30 minutes prior to exposure to motion stimuli. It should be placed behind the ear on the mastoid on a clean, hairless area.
Many antihistamines are also commonly taken for motion sickness. They are available over the counter and can be used for pediatrics at the recommended doses. They should also be used to prevent motion sickness rather than treating it.
Their effectiveness is likely due to both their central antihistamine and central anticholinergic properties. The nonsedating antihistamines like cetirizine that do not cross the blood-brain barrier are not effective in either preventing or treating motion sickness.
Common side effects can include: dry mouth/nose/throat, drowsiness and sensitivity to bright light (secondary to mydriasis). Less common include palpitations, urinary retention, bloating, constipation, headache and confusion. They should be taken 1 hour prior to departure.
Cinnarizine (Stugeron) is an antihistamine (not marketed in the US), that is reported to be effective if administered at a 50mg oral dose before a rough voyage.  Although cinnarizine is not licensed by the FDA in the United States, several studies report cinnarizine as the most effective antihistamine with the fewest side effects. 
Dimenhydrinate (Dramamine, Gravol, Driminate), Meclizine (Bonine, Bonamine, Antivert, Postafen, and Sea Legs), and Cyclizine ( Marezine, Bonine For Kids, Cyclivert) are long-acting piperazine antihistamines and generally cause less sedation than other antihistamines.
Promethazine (Phenergan) is prescribed for treating nausea or vomiting, motion sickness, and allergic reactions, but causes more sedation than other antihistamines.
Sympathomimetics, while have shown some effectiveness in preventing and treating motion sickness, are most commonly used to counteract the sedation of other motion sickness treatments. They have not been shown to be superior to other medications. Due to concerns regarding their addictive potential, they are not as often prescribed.
While having been shown to have some efficacy in preventing motion sickness, these are a controlled substance with a high abuse potential, and therefore should be prescribed with caution. 
Caffeine has been shown to be of benefit in treating motion sickness only when combined with other pharmacological treatments such as promethazine. 
Antiemetics are taken to relieve nausea, but have not been shown to prevent motion sickness.
Ondansetron is the most often recommended antiemetic but has been shown to be a poor treatment choice for motion sickness. [29, 30]
Benzodiazepines such as diazepam have been shown to prevent motion sickness but not as well as other options.  This fact, along with its sedation properties, make it a poor choice. However, for resistant and severe cases, especially for patients with incapacitating motion sickness, a benzodiazepine, if used safely, may be the most humane option.