Medication Summary
The goal of pharmacological therapy is to prevent motion sickness, or relieve the symptoms of motion sickness, such as nausea.
Anticholinergic agents
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.
Antihistamines
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. [29]
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.
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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. [30] 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. [31]
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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.
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Promethazine (Phenergan) is prescribed for treating nausea or vomiting, motion sickness, and allergic reactions, but causes more sedation than other antihistamines.
Sympathomimetics
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.
Amphetamines
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. [32]
Caffeine
Caffeine has been shown to be of benefit in treating motion sickness only when combined with other pharmacological treatments such as promethazine. [33]
Other medications
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. [34, 35]
Benzodiazepines such as diazepam have been shown to prevent motion sickness but not as well as other options. [36] 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.
Anticholinergic Agents
Class Summary
Alkaloids with anti-cholinergic properties that are used for the prevention of motion sickness rather than acute treatment.
Scopolamine
Scopolamine is most commonly used as a transdermal patch that is applied behind the ear for up to 72 hours, at which point it can be replaced. Transdermal scopolamine is the most effective pharmaceutical for the prevention and treatment of motion sickness. [32, 33] The patch should be applied 4 hours prior to departure. [34]
Oral tablets are also available and should be taken 1 hour prior to departure at their recommended doses. Some experts report the dose can be safely doubled by wearing either two patches or by supplementing the patch with oral scopolamine. [35, 36] Intranasal scopolamine may also work. [37] Scopolamine may also be used in conjunction with antihistamines, although this will increase the chance of the user experiencing side effects.
Piperazine Antihistamines
Class Summary
Long-acting piperazine antihistamines generally cause less sedation than other antihistamines.
Dimenhydrinate
Mixture of 1:1 salt consisting of 8-chlorotheophylline and diphenhydramine. Believed to be useful, particularly in treatment of vertigo. Diminishes vestibular stimulation and depresses labyrinthine function through central anticholinergic effects. However, prolonged treatment may decrease rate of recovery of vestibular injuries.
Meclizine
Decreases excitability of middle ear labyrinth and blocks conduction in middle ear vestibular-cerebellar pathways. These effects are associated with relief of nausea and vomiting.
Cyclizine
Mechanisms of action are not understood. In nausea, and other vertigo symptoms, may have an effect on labyrinthine apparatus, chemoreceptor trigger zone, in addition to central actions.
Sympathomimetics
Class Summary
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.
Ephedrine
One study showed ephedrine used in combination with an antihistamine (chlorphenamine) was effective in treating some symptoms of motion sickness once they have begun and was reported to decrease the sedative effects of the antihistamine. [38]
