What are the medications for treating motion sickness?

Medications for Motion Sickness

Transdermal scopolamine is the first-line medication for prevention of motion sickness and should be applied behind the ear at least 4-6 hours before anticipated motion exposure. 1, 2

First-Line Medications

Scopolamine

• Transdermal delivery system (patch):
  • Contains 1.5mg scopolamine programmed to deliver 0.5mg over 3 days
  • Apply to hairless area behind ear at least 4-6 hours before anticipated motion (ideally 8-12 hours for maximum effectiveness)
  • Provides protection for up to 72 hours
  • Achieves protective plasma concentration (50 pg/mL) after 6 hours
  • Most effective 8-12 hours after application 1, 3
  • For faster protection, can combine with oral scopolamine (0.3 or 0.6mg) 3

First-Generation Antihistamines

• Dimenhydrinate:

  • Effective for prevention of motion sickness symptoms
  • Higher sedation rate compared to scopolamine (approximately 66% vs 44% for placebo) 4

• Cinnarizine:

  • Effective for prevention of motion sickness under natural conditions
  • Moderate sedation profile 4, 5

• Meclizine:

  • Similar adverse effect profile to scopolamine
  • Less effective than scopolamine but better tolerated than some other antihistamines 3

Second-Line Options

Combination Therapies

• Promethazine plus ephedrine:
  • Similar efficacy to scopolamine 3
  • Useful when first-line agents are ineffective or contraindicated

Ineffective Medications

• Nonsedating (second-generation) antihistamines
• Ondansetron
• Ginger root 2

Medication Selection Algorithm

1. For journeys lasting >6 hours:

   • Transdermal scopolamine (apply 4-8 hours before travel)

2. For shorter journeys or when scopolamine is contraindicated:

   • First-generation antihistamines (dimenhydrinate, cinnarizine, or meclizine)

3. For rapid onset of protection:

   • Combination of transdermal scopolamine with oral scopolamine (0.3-0.6mg)

4. For patients with contraindications to both scopolamine and antihistamines:

   • Consider non-pharmacological strategies (positioning, visual fixation, behavioral techniques)

Common Side Effects and Management

Scopolamine

• Common: Dry mouth (50-60%), drowsiness (up to 20%), allergic contact dermatitis (10%)
• Less common: Transient vision impairment, difficulty urinating, headache
• Management: Low-dose pyridostigmine can prevent cycloplegia but not mydriasis 3

Antihistamines

• Common: Sedation (higher than scopolamine), cognitive impairment
• Less common: Blurred vision, dry mouth
• Management: Take at bedtime if traveling overnight to minimize impact of sedation

Special Populations

Pregnant Women

• Metoclopramide may be used under supervision for associated nausea 6
• Scopolamine and antihistamines generally not recommended during pregnancy

Breastfeeding Women

• Consider interruption of breastfeeding when using scopolamine or antihistamines 1

Important Considerations

• Behavioral strategies should complement pharmacological approaches:

  • Position in the most stable part of the vehicle
  • Watch the true visual horizon
  • Lie down with eyes closed when possible
  • Minimize other sources of physical or emotional discomfort 2

• Early self-diagnosis and preventive treatment are critical for effectiveness

• Habituation through repeated exposure remains the most effective non-pharmacological approach 7, 5

Motion sickness medications primarily work by addressing the sensory conflict between vestibular, visual, and proprioceptive systems that causes symptoms. Transdermal scopolamine offers the best balance of efficacy and side effect profile, particularly for longer journeys.