| Antimuscarinic Agents Scopolamine Available in transdermal patch (1.5 mg), tablets (0.4 mg), and intramuscular injection Brands: Scopace, Transderm-scop | Patch: apply to hairless area behind ear at least 4 hrs before travel. Remove or replace with new patch after 72 hrs. Do not cut patch in half. Oral: 0.4-0.8 mg every 8 hrs. Take about 1 hr before travel. IM: 0.3-0.6 mg every 6-8 hrs. | Contraindicated in glaucoma, urinary retention, gastrointestinal (GI) obstruction, ulcerative colitis, myasthenia gravis, hypersensitivity Caution in extreme heat, thyroid, cardiopulmonary, gastroesophageal reflux, liver, or kidney disease, seizure or psychotic disorder, autonomic neuropathy Should not be used in children. | Common: dry mouth/nose/throat, blurred vision, drowsiness Less common: dry skin, contact dermatitis (from patch), palpitations, urinary retention, nausea, vomiting, bloating, constipation, loss of taste, headache, confusion, memory impairment, paradoxical hyperexcitability, insomnia, acute toxic psychosis Withdrawal symptoms after patch removal: nausea, vomiting, headache, dizziness, weakness, bradycardia, hypotension | Additive effects with alcohol and other CNS depressants, anticholinergics, antihistamines, some antidepressants (e.g., tricyclic antidepressants), and other neurologic drugs. Antacids impair absorption of oral scopolamine. Scopolamine may significantly impair GI motility when used with antidiarrheal drugs. Scopolamine impairs absorption of oral medications. Scopolamine may increase risk of GI lesions related to potassium chloride use. | Caution when operating machinery, driving a car, or engaging in underwater sports. Wash hands after patch application to prevent transfer to eye. FDA Pregnancy category C |
| Antihistamines | | Contraindicated in hypersensitivity Caution in glaucoma, urinary retention, GI obstruction, liver or kidney disease, chronic obstructive pulmonary disease (COPD), seizure disorder | Common: drowsiness, anticholinergic symptoms (dry mouth/nose/throat, 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 hyperexcitability, seizures, psychosis, acute dystonic reaction, paresthesias, photosensitivity, anaphylaxis | Additive effects with alcohol and other CNS depressants, anticholinergics, 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 with food or milk to reduce nausea. |
| Dimenhydrinate Available in 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 | Oral: Take at least 30 min before travel. 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 Children <12 yrs: 1.25 mg/kg every 6 hrs, max 300 mg per day | Should not be used in children <2 yr | | May block effectiveness of apomorphine | FDA Pregnancy category B |
| Diphenhydramine Available in oral capsules and tablets (25 mg, 50 mg), elixir (12.5 mg/5 mL), and intramuscular injection (10 or 50 mg/mL) Multiple brands available | Oral: Take at least 30 min before travel. Adults: 10-50 mg every 4-6 hrs Children (6-12 yrs): 12.5-25 mg every 4-6 hrs 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 | Not recommended in infants or neonates | | | FDA Pregnancy category B |
| Promethazine Available in oral tablets (12.5 mg, 25 mg, 50 mg), syrup (6.25 mg/5 mL, 25 mg/5 mL), rectal suppositories, and intramuscular injection. Brands: Phenergan, Promacot | Oral: Take at least 30 min before travel. Adults: 25 mg every 8-12 hrs Contraindicated in children under 2 and not recommended for children <16 yrs (12) | Also caution in sulfa allergy (some formulations contain sulfite), cardiovascular disease, peptic ulcer disease | Pronounced sedation, postural hypotension, skin rash, body temperature dysregulation, extrapyramidal symptoms, delirium, neuroleptic malignant syndrome | May interact with other neurologic drugs. Epinephrine may worsen hypotension when used with antihistamine. | FDA Pregnancy category C |
| Meclizine Available in chewable and nonchewable tablets (12.5 mg, 25 mg, 50 mg) Brands: Antivert (Rx), Bonine (OTC), Dramamine II (OTC), Meclicot (Rx), Medivert (Rx) | Oral: Take 1 hour before travel. Adults: 25-50 mg every 24 hrs Not recommended for children <12 yrs | | | May block effectiveness of apomorphine. | |
| Cyclizine Available in oral tablets (50 mg) Brands: Marezine (OTC) | Oral: Take 30 min before travel Adults: 50 mg every 4-6 hrs, max 200 mg per day Not recommended for children <12 yrs IM: Adults: same as oral dose | Caution in heart failure | | | |
