Motion Sickness Description Motion sickness, a common problem in travelers by automobile, train, air, and particularly sea, usually causes mild to moderate discomfort but in severe cases can be incapacitating. It affects up to half of children traveling in automobiles or airplanes and almost 100% of boat passengers in very rough seas. Small boats and cars tend to be the most provocative stimulus for motion sickness (1). Motion sickness is more common in women (especially during pregnancy or menstruation), children ages 2 12 years, and persons who have migraine headaches, but little is known about individual susceptibility (2,3). Head position and movement are sensed by the vestibular organs, the semicircular canals (angular acceleration or rotation) and otolith organs (vertical acceleration), in the inner ears. The vestibular organs generate signals that are transmitted to the central nervous system via cranial nerve VIII. Proprioceptors and visual receptors also send signals to the central nervous system about the body s relative position in space, but the vestibular system plays a critical role in the development of motion sickness. The signs and symptoms of motion sickness occur when sensory information about the body s position in, or movement through, space is contradictory or contrary to prior experience (4). Clinical Presentation Classic symptoms of motion sickness include abdominal discomfort, nausea, vomiting, dizziness, pallor, and cold sweats. Delayed stomach emptying and changes in normal gastric rhythm have been associated with stomach symptoms (5). Prevention Travelers who are susceptible to motion sickness can reduce symptoms by minimizing situational triggers and engaging in certain behavioral countermeasures: choose seats with the smoothest ride, usually the front seat of a car, forward cars of a train, center of a boat, and the seats over the wings in an airplane; focus on distant objects or keep eyes closed instead of reading or looking at something inside the vehicle; minimize head movement; and, if necessary, lie supine (1,3,4). Symptoms usually improve substantially within 15 minutes of stopping motion, when stomach motility has returned to normal (5). Travelers with repeated exposure to similar types of motion within a short period of time may develop tolerance or adapt to that motion (1,6). Treatment Medications that may ameliorate symptoms of motion sickness include anticholinergic agents and antihistamines. For the prevention of motion sickness symptoms, medications are available in either oral or transdermal formulations. All oral medications should be taken at least 30 60 minutes before travel to allow adequate absorption time, as absorption may be impaired by the gastric dysmotility caused by motion. Choice of medication is based on trip duration, underlying medical conditions, concerns about sedation, and personal preference (Table 6 1).
Scopolamine, an antimuscarinic agent that blocks cholinergic input from the vestibular organs to the CNS, is available in oral and transdermal preparations. Transdermal scopolamine is appropriate for longer voyages and may lessen severity of symptoms in all common modes of travel. One patch should be applied to the bare area behind the ear at least 4 hours before departure and changed every 3 days as needed. The patch should be applied 8 hours before departure to obtain maximal effect (7). Oral scopolamine is effective for 6 8 hours and can be used for short journeys or for the interval between application of the patch and onset of effectiveness. Transdermal scopolamine is associated with fewer side effects than oral scopolamine (8). The most common side effect is dry mouth, which is experienced by up to two thirds of travelers and is a frequently cited reason for discontinuation of use (9). Other side effects include blurred vision (especially for persons with hyperopia), dilated pupils, reduced visual accommodation, and bradycardia, all of which may appear or worsen 24 hours after patch application and with successive patch uses (7). Scopolamine is less sedating than the antihistamines and has not been shown to adversely affect psychomotor performance (1,7,9).Travelers may have rebound sensitivity to vestibular stimulation following patch removal and may experience withdrawal symptoms of headache, nausea, vomiting, and dizziness (4,7). Antihistamines used for the prevention of motion sickness include oral dimenhydrinate, diphenhydramine, promethazine, meclizine, and cyclizine. Promethazine primarily decreases nausea and may be more effective than other antihistamines, but it is the most sedating medication (8). Meclizine is less sedating and requires only once a day dosing, because its duration of action is up to 24 hours (8). Compared with dimenhydrinate (50 mg) and meclizine (50 mg), promethazine (25 mg) has the greatest adverse impact on psychomotor performance, both in severity and duration of side effects. Dimenhydrinate (100 mg) has also been shown to impair psychomotor performance compared with placebo (9). All antimotion sickness medications can impair alertness and must be used with caution by persons operating vehicles or heavy machinery or engaging in underwater activities. This effect is additive with alcohol and other central nervous system depressants. In addition, because these drugs all have anticholinergic properties, they should be avoided in travelers with narrow angle glaucoma, gastrointestinal obstruction, or urinary retention (e.g., prostatic hypertrophy); they should be used with caution by travelers with cardiovascular, pulmonary, liver or kidney disease. Only dimenhydrinate and diphenhydramine are recommended for use in children. They may cause paradoxical excitation and should not be used in children <2 years of age (8,10). Nonpharmacologic remedies for motion sickness may benefit some persons but have not been proven consistently effective. Ginger has been shown to relieve pregnancyrelated nausea and vomiting, but there is conflicting evidence about its use in motion sickness (11). Differences in sources and preparations of ginger may account for some of the variability. Pressure on the P6 neiguan acupuncture point of the wrist provides relief of nausea in pregnancy and after chemotherapy, but evidence for efficacy in motion sickness is contradictory.
TABLE 6 1. Antimotion Sickness Medications MEDICATI EFFEC Common: dry and mouth/nose/thr other CNS oat, blurred depressants, Contraindicat vision, anticholinergic ed in drowsiness s, glaucoma, antihistamines, urinary some retention, antidepressants Patch: apply gastrointestin Less common: (e.g., tricyclic to hairless al (GI) dry skin, antidepressants area behind obstruction, contact Caution ), and other ear at least 4 ulcerative dermatitis when Antimuscarin neurologic hrs before colitis, (from patch), operating ic Agents drugs. travel. myasthenia palpitations, machinery, Remove or gravis, urinary driving a replace with hypersensitivi retention, car, or new patch ty nausea, engaging in Scopolamine Antacids after 72 hrs. vomiting, underwater impair Do not cut bloating, sports. absorption of patch in constipation, transdermal oral half. Caution in loss of taste, patch (1.5 scopolamine. extreme heat, headache, mg), tablets thyroid, confusion, Wash hands (0.4 mg), and Scopolamine cardiopulmon memory after patch intramuscular may Oral: 0.4 0.8 ary, impairment, application injection significantly mg every 8 gastroesophag paradoxical to prevent impair GI hrs. Take eal reflux, hyperexcitabili transfer to Brands: motility when about 1 hr liver, or ty, insomnia, eye. Scopace, used with before kidney acute toxic Transderm antidiarrheal travel. disease, psychosis FDA scop drugs. seizure or Pregnancy IM: 0.3 0.6 psychotic Withdrawal category C Scopolamine mg every 6 disorder, symptoms impairs 8 hrs. autonomic after patch absorption of neuropathy Should not be used in children. removal: nausea, vomiting, headache, dizziness, weakness, bradycardia, hypotension Additive effects with alcohol oral medications. Scopolamine may increase risk of GI lesions related to potassium chloride use.
MEDICATI Antihistamin es Dimenhydrina te Contraindicat ed in hypersensitivi ty Caution in glaucoma, urinary retention, GI obstruction, liver kidney disease, chronic obstructive pulmonary disease (COPD), seizure disorder or Oral: Take Should not be at least 30 used in min before children <2 yr EFFEC Common: drowsiness, anticholinergic symptoms (dry mouth/nose/thr oat, blurred vision, urinary retention), thick respiratory secretions Less common: dizziness, weakness, hypotension or hypertension, cardiac arrhythmia, wheezing, sweating, nausea, vomiting, bloating, diarrhea, constipation, jaundice, anorexia, headache, confusion, tinnitus, paradoxical hyperexcitabili ty, seizures, psychosis, acute dystonic reaction, paresthesias, photosensitivit y, anaphylaxis Additive effects with alcohol and other CNS depressants, anticholinergic s, some antidepressants (e.g., tricyclic antidepressants ) and use of more than one antihistamine. Antihistamine effects may be potentiated by monamine oxidase inhibitors. Antacids may impair absorption of antihistamines. Caution when operating machinery, driving a car, or engaging in underwater sports Take food milk reduce nausea. with or to May block FDA effectiveness Pregnancy of category B apomorphine
MEDICATI travel. EFFEC chewable and nonchewable tablets (50 mg), syrup (12.5 mg/ 5 ml), rectal suppositories, and intramuscular injection (50 mg/ml). Brands: Calm X, Dramamine, Triptone Adults: 50 100 mg every 4 6 hrs, max 400 mg per day Children (6 12 yrs): 25 50 mg every 6 8 hrs, max 150 mg per day Children (2 6 yrs): 12.5 25 mg every 6 8 hrs, max 75 mg per day Rectal: Children (8 12 yrs): 25 50 mg every 8 12 hrs Children (6 8 yrs): 12.5 25 mg every 8 12 hrs IM: Adults: same as oral dose Diphenhydra mine Children <12 yrs: 1.25 mg/kg every 6 hrs, max 300 mg per day Oral: Take Not at least 30 recommended min before in infants or FDA Pregnancy category B
MEDICATI travel. neonates EFFEC oral capsules and tablets (25 mg, 50 mg), elixir (12.5 mg/5 ml), and intramuscular injection (10 or 50 mg/ml) Adults: 10 50 mg every 4 6 hrs Children (6 12 yrs): 12.5 25 mg every 4 6 hrs Multiple brands available Children (<6 yrs): 6.25 12.5 mg every 4 6 hrs IM: Adults: start 10 mg, may increase up to 50 mg, every 2 3 hrs, max 400 mg per day Children: 1 1.5 mg/kg every 6 hrs, max 300 mg per day Oral: Take at least 30 Promethazine Also caution min before in sulfa travel. allergy (some formulations oral tablets Adults: 25 contain (12.5 mg, 25 mg every 8 sulfite), mg, 50 mg), 12 hrs cardiovascula syrup (6.25 r disease, mg/5 ml, 25 Contraindica peptic ulcer mg/5 rectal ml), ted children in disease Pronounced sedation, postural hypotension, skin rash, body temperature dysregulation, extrapyramidal symptoms, delirium, neuroleptic malignant May with neurologic drugs. Epinephrine interact other may worsen hypotension when used with antihistamine. FDA Pregnancy category C
MEDICATI suppositories, and intramuscular injection. Brands: Phenergan, Promacot Meclizine under 2 and not recommende d for children <16 yrs (12) EFFEC syndrome chewable and nonchewable tablets (12.5 mg, 25 mg, 50 mg) Oral: Take 1 hour before travel. Adults: 25 50 mg every 24 hrs Brands: Not Antivert (Rx), recommende Bonine d for (OTC), children <12 Dramamine II yrs (OTC), Meclicot (Rx), Medivert (Rx) Oral: Take 30 min before travel May block effectiveness of apomorphine. Cyclizine Adults: 50 mg every 4 6 hrs, max 200 mg per day Caution in oral tablets heart failure (50 mg) Not recommende Brands: d for Marezine (OTC) children <12 yrs IM: Adults: same as oral dose
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