Does Gravol (dimenhydrinate) decrease the seizure threshold?

Gravol (Dimenhydrinate) and Seizure Threshold

Yes, Gravol (dimenhydrinate) can decrease seizure threshold and should be used with caution in patients with seizure disorders or those at risk for seizures. 1

Mechanism and Risk

• Dimenhydrinate, like other antihistamines with anticholinergic properties, can lower the seizure threshold when taken in therapeutic doses and poses a greater risk at higher doses 2
• Similar to medications like meperidine, dimenhydrinate has been specifically identified as decreasing seizure threshold in clinical guidelines 3
• The World Journal of Emergency Surgery guidelines specifically contraindicate dimenhydrinate in patients with a history of seizures 1

Clinical Evidence of Seizure Risk

• Case reports document seizures associated with dimenhydrinate use, particularly in vulnerable populations:
  • A 13-month-old child experienced three generalized tonic-clonic seizures after receiving multiple dimenhydrinate suppositories (total 40mg) over two days 4
  • Seizure activity has been documented with both therapeutic and supratherapeutic doses 4, 5

Risk Factors for Dimenhydrinate-Induced Seizures

• Pre-existing seizure disorder or history of seizures 1
• High doses or overdose situations 2
• Pediatric patients may be particularly vulnerable 4
• Concurrent use of other medications that lower seizure threshold 2
• Renal or hepatic impairment that may affect drug clearance 3

Management Recommendations

• Avoid dimenhydrinate in patients with known seizure disorders or history of seizures 1
• If antiemetic therapy is necessary in patients with seizure risk, consider alternative medications with less impact on seizure threshold 3
• For patients requiring dimenhydrinate who have risk factors but no seizure history:
  • Use the lowest effective dose 2
  • Monitor for signs of central nervous system toxicity 5
  • Avoid combining with other medications that lower seizure threshold 2

Other Considerations

• Dimenhydrinate is also associated with other central nervous system effects including drowsiness, which is a common side effect 6
• In cases of abuse or high-dose use, dimenhydrinate can cause euphoria, hallucinations, and other psychiatric symptoms 5
• Withdrawal from chronic high-dose use may require medical management 5

Alternative Antiemetics for Patients with Seizure Risk

• Consider 5-HT3 antagonists (e.g., ondansetron) which have not been associated with significant seizure risk 3
• Dopamine antagonists may be used with caution, though some also carry seizure risk 3

Remember that the seizure risk with dimenhydrinate appears dose-dependent, with higher risk at supratherapeutic doses, but caution is warranted even at standard therapeutic doses in vulnerable patients 4, 2.