In an adult (especially >65) patient, can diazepam be used for travel (motion) sickness, and what dose, contraindications (e.g., COPD, sleep apnea, hepatic impairment, pregnancy, benzodiazepine dependence) and alternative therapies should be considered?

Diazepam for Travel (Motion) Sickness

Diazepam is not recommended as a first-line agent for motion sickness; scopolamine (transdermal patch) and first-generation antihistamines (dimenhydrinate, meclizine) are the evidence-based treatments of choice. 1, 2, 3

Evidence for Diazepam in Motion Sickness

While one small experimental study from 1982 demonstrated that diazepam had antimotion sickness properties comparable to dimenhydrinate when tested in controlled laboratory conditions (rotating chair with head movements), this represents low-quality evidence from a single trial and has not been replicated or validated in clinical practice guidelines. 4

Critically, diazepam is not mentioned in any current motion sickness treatment guidelines or systematic reviews as a recommended agent, despite extensive literature searches covering decades of research. 1, 5, 2, 3

Recommended First-Line Treatments

Scopolamine (Hyoscine)

• Transdermal scopolamine is the most effective first-line pharmacological agent for motion sickness prevention, with moderate-quality evidence showing superiority over placebo. 1, 2, 3
• The patch should be applied several hours before anticipated motion exposure (typically 4-6 hours prior) for optimal effectiveness. 1
• Common side effects include dry mouth, drowsiness, and blurred vision. 2, 3

First-Generation Antihistamines

• Dimenhydrinate and meclizine are effective alternatives with moderate-certainty evidence showing they prevent motion sickness symptoms in approximately 40% of susceptible individuals versus 25% with placebo (RR 1.81,95% CI 1.23-2.66). 5
• These agents are sedating, which is part of their mechanism but also a significant side effect. 1, 5
• Nonsedating antihistamines are NOT effective for motion sickness. 1

Critical Contraindications for Diazepam

Even if one were to consider diazepam off-label, multiple absolute contraindications exist that make it inappropriate for most travelers:

Respiratory Contraindications

• Diazepam is absolutely contraindicated in patients with severe respiratory insufficiency, COPD, or sleep apnea syndrome due to dose-dependent respiratory depression. 6, 7
• The respiratory depressant effect results from depression of the central ventilatory response to hypoxia and hypercapnea. 7

Hepatic Impairment

• Diazepam is contraindicated in severe hepatic insufficiency. 6
• Diazepam has a prolonged half-life (20-120 hours) with active metabolites (desmethyldiazepam with half-life 50-95 hours) that accumulate significantly in hepatic dysfunction. 8
• Clearance is markedly reduced in elderly patients and those with liver disease. 7, 8

Age-Related Concerns (Adults >65)

• The 2019 American Geriatrics Society Beers Criteria strongly recommend avoiding benzodiazepines in older adults due to increased risk of cognitive impairment, delirium, falls, fractures, and motor vehicle accidents. 7
• Benzodiazepine clearance decreases with age, and diazepam's long half-life makes prolonged sedation especially problematic in elderly patients. 8
• Doses should be reduced by ≥20% in patients over 60 years if benzodiazepines must be used. 7

Pregnancy

• Benzodiazepines cross the placenta, and their use during pregnancy requires careful risk-benefit assessment. 8

Dependence Risk

• All benzodiazepines carry substantial risk of physical and psychological dependence, with withdrawal symptoms including seizures, hallucinations, and potentially life-threatening complications upon abrupt cessation. 8
• Diazepam's long half-life and active metabolites increase the risk of accumulation with repeated dosing. 8

Other Contraindications

• Myasthenia gravis (absolute contraindication). 6
• Acute narrow-angle glaucoma (absolute contraindication). 6

Safer Alternative Approach for Motion Sickness

Behavioral Strategies (First-Line, No Contraindications)

• Position yourself in the most stable part of the vehicle (front seat of car, middle of ship, over wings in aircraft). 1
• Watch the true visual horizon and avoid reading or screen use during travel. 1
• Steer the vehicle when possible or tilt your head into turns. 1
• Lie down with eyes closed if symptoms develop. 1
• Minimize other sources of discomfort (avoid heavy meals, alcohol, strong odors before travel). 1

Pharmacological Options (When Behavioral Strategies Insufficient)

1. Scopolamine transdermal patch (apply 4-6 hours before travel) 1, 2, 3
2. Dimenhydrinate 50 mg (take 30-60 minutes before travel; may repeat every 4-6 hours) 5, 4
3. Meclizine 25-50 mg (take 1 hour before travel; lasts 12-24 hours) 5

Agents That Do NOT Work

• Ondansetron (5-HT3 antagonist) is NOT effective for motion sickness. 1
• Ginger root is NOT effective for motion sickness. 1
• Nonsedating antihistamines are NOT effective. 1

Common Pitfalls to Avoid

• Do not prescribe diazepam for motion sickness when evidence-based alternatives (scopolamine, first-generation antihistamines) are available and have superior safety profiles. 1, 5, 2, 3
• Do not use benzodiazepines in elderly patients (>65 years) for motion sickness due to unacceptable fall risk, cognitive impairment, and prolonged sedation from drug accumulation. 7, 8
• Do not prescribe diazepam to patients with any respiratory disease (COPD, sleep apnea) as it is absolutely contraindicated. 6, 7
• Do not combine diazepam with alcohol or opioids due to synergistic respiratory depression and potentially fatal overdose risk. 7, 8
• Do not assume diazepam is "safer" than approved motion sickness medications—it carries significantly more contraindications and adverse effects than scopolamine or antihistamines. 7, 6