Drug-induced yawning: a review of the French pharmacovigilance database

To review the reports with 'yawning' as an adverse drug reaction (ADR) reported into the French Pharmacovigilance Database.

All the observations with 'yawning' reported in the French Pharmacovigilance Database until December 2004 were reviewed. We recorded drug(s) involved, characteristics of patients (age, sex and underlying disease) and of ADR (seriousness, delay in occurrence, evolution, imputability).

Twenty-eight reports were recorded between 1985 and December 2004. The sex ratio of the patients included in these reports was 1.5 and the mean age was 46.2 (2-78) years. Thirty-eight drugs were involved, mainly serotoninergic agents (serotonin reuptake inhibitors [12]), dopaminergic agents (levodopa [3], dopamine agonists [3], monoamine oxidase B inhibitor [1]), opioids (morphine [1], methadone [1], buprenorphine [1], dextromethorphan [1]), benzodiazepines (4) and sodium channel inhibitors (lidocaine [2], flecainide [1]). Four ADRs were rated 'serious' (leading to hospitalisation). Patient outcome was usually favourable after drug withdrawal.

Despite its necessary methodological drawbacks (mainly under-reporting), this study reveals that several drugs may induce yawning in humans. Our work also indicates that stimulation of central dopamine or serotonin receptors elicits yawning in humans. This study underlines the role of several drugs in yawning and shows that this ADR is not systematically listed in the summary product characteristic even when it can be explained by the pharmacodynamic properties of the drugs.