What is the best medication for motion sickness: Scopolamine, Meclizine (Antivert), or Promethazine (Phenergan)?

Scopolamine is the Most Effective Medication for Motion Sickness

Scopolamine is the first-line medication for prevention of motion sickness, being more effective than meclizine (Antivert) or promethazine (Phenergan). 1

Comparison of Effectiveness

• Scopolamine has been shown to be significantly superior to placebo in reducing the incidence and severity of motion sickness by 60-80% 2
• Scopolamine is more effective than oral meclizine and similar to or superior to promethazine in preventing motion sickness 2
• Transdermal scopolamine produces only about half the incidence of drowsiness caused by antihistamines like meclizine 2
• Scopolamine works by blocking acetylcholine, a neurotransmitter in the central nervous system, helping reduce the neural mismatch that causes motion sickness 3

Dosing and Administration

• For motion sickness, apply one scopolamine transdermal patch to the hairless area behind one ear at least 4 hours before the antiemetic effect is required (ideally 6-8 hours before) 4
• The patch delivers approximately 1 mg of scopolamine over 3 days 4
• For faster protection, the patch may be applied 1 hour before travel in combination with oral scopolamine 2
• If therapy is required for longer than 3 days, remove the first patch and apply a new one behind the other ear 4

Side Effects and Precautions

• Common side effects of scopolamine include dry mouth (50-60% of users), drowsiness (up to 20%), and allergic contact dermatitis (10%) 2
• Scopolamine is contraindicated in patients with angle closure glaucoma 4
• Scopolamine can cause neuropsychiatric adverse reactions including cognitive impairment, disorientation, and confusion 4
• Elderly patients may be more sensitive to the neurological and psychiatric effects of scopolamine 4

Alternative Options

Meclizine (Antivert)

• Meclizine is an antihistamine commonly used for motion sickness at doses of 12.5-25 mg three times daily 5
• While effective for some patients, studies show it is less effective than scopolamine 2
• Meclizine has a similar side effect profile to other antihistamines but causes less drowsiness than some alternatives 2

Promethazine (Phenergan)

• Promethazine is a phenothiazine with antihistamine properties used for motion sickness 3
• The usual dose is 12.5 to 25 mg, infused slowly intravenously (25 mg/min) or taken orally 5
• Side effects include hypotension, respiratory depression, neuroleptic malignant syndrome, and extrapyramidal effects 5
• Promethazine has been found effective in alleviating symptoms of severe motion sickness in some studies 6

Special Considerations

• For long journeys (6-12 hours or longer), scopolamine is particularly advantageous to avoid repeated oral doses 2
• Behavioral strategies should also be employed, such as watching the true visual horizon, steering the vehicle when possible, tilting the head into turns, or lying down with eyes closed 1
• Nonsedating antihistamines, ondansetron, and ginger root are not effective in the prevention and treatment of motion sickness 1
• Medications for motion sickness should not be used long-term as they may interfere with central compensation in vestibular conditions 3

Algorithm for Selection

1. For most patients without contraindications: Scopolamine transdermal patch (first-line) 1
2. For patients who cannot use scopolamine (contraindications or side effects): Meclizine 12.5-25 mg three times daily 5
3. For severe cases where rapid onset is needed: Promethazine 12.5-25 mg 5
4. For very long journeys: Scopolamine patch is preferred to avoid repeated dosing 2