Medication for Sea Sickness
Transdermal scopolamine is the most effective medication for preventing sea sickness, providing a 75% reduction in motion-induced nausea and vomiting when applied 4-16 hours before travel. 1
First-Line Recommendation: Transdermal Scopolamine
Apply the scopolamine transdermal patch to the hairless area behind one ear 4-16 hours before anticipated motion exposure. 1 The patch delivers approximately 1 mg of scopolamine over 3 days, with peak plasma concentrations reached within 24 hours of application. 1
Clinical Efficacy
- In studies conducted at sea with 195 adult subjects, transdermal scopolamine demonstrated a 75% reduction in motion-induced nausea and vomiting. 1
- A 3-day sailing study showed protection rates of 74%, 73%, and 39% on successive days, with no significant side effects compared to placebo. 2
- When compared directly to oral dimenhydrinate and placebo at sea, transdermal scopolamine was significantly more effective (p = 0.0001) than placebo. 3
Administration Details
- Only wear one patch at a time; do not cut the patch. 1
- Apply to clean, dry, hairless skin behind the ear. 1
- Wash hands thoroughly with soap and water immediately after handling to avoid accidental eye contact. 1
- If the patch becomes displaced, discard it and apply a new one behind the other ear. 1
- After removal, fold the used patch in half (sticky sides together) and dispose in household trash away from children and pets. 1
Side Effects
- Minimal dry mouth, drowsiness, and blurred vision were reported with transdermal scopolamine. 3
- The patch acts centrally by blocking cholinergic transmission from vestibular nuclei to higher CNS centers. 1
Alternative: First-Generation Antihistamines
If scopolamine is contraindicated or unavailable, first-generation antihistamines (cinnarizine or dimenhydrinate) are probably effective alternatives, preventing symptoms in approximately 40% of susceptible individuals compared to 25% with placebo. 4
Antihistamine Options
- Cinnarizine, dimenhydrinate, cyclizine, or meclozine can be used for prevention. 5, 4
- A comparative study of seven agents found that cinnarizine, cinnarizine with domperidone, cyclizine, dimenhydrinate with caffeine, and meclozine with caffeine all showed similar efficacy (4.1-10.2% experienced vomiting; 16.4-23.5% experienced malaise). 5
- Scopolamine transdermal system was slightly less effective in this head-to-head comparison and caused more visual problems. 5
Important Caveat
- Antihistamines may be more likely to cause sedation compared to placebo (66% vs 44%), which could impair performance during sailing. 4
- They may result in little or no difference in blurred vision (14% vs 12.5%) or impaired cognition (29% vs 33%) compared to placebo. 4
What NOT to Use
Ondansetron (a 5-HT3 blocker) is not effective for sea sickness prevention. 6 A double-blind study of 16 volunteers at sea found no statistically significant reduction in seasickness symptoms with ondansetron 8 mg compared to placebo (Wiker score 2.69 vs 2.81). 6 The mechanism of nausea in motion sickness appears different from toxin-induced nausea, where 5-HT3 blockers are effective. 6
Practical Algorithm
For most adults planning sea travel: Apply transdermal scopolamine patch 4-16 hours before departure. 1
If scopolamine is contraindicated (e.g., glaucoma, urinary retention) or causes intolerable side effects: Use first-generation antihistamines such as dimenhydrinate or meclozine starting 1-2 hours before travel. 5, 4
Avoid ondansetron as it has not demonstrated efficacy for motion sickness. 6
Monitor for side effects: Wash hands after patch application to prevent accidental eye contamination, which can cause pupil dilation and visual disturbances. 1