[2] Anecdotal reports describe high doses of diphenidine producing "bizarre somatosensory phenomena and transient anterograde amnesia.

[7] The two enantiomers of diphenidine differ greatly in their ability to block the NMDA receptor, with the more potent (S)-enantiomer possessing affinity forty times higher than the (R)-enantiomer.

[12][13] Since 2014 there have been several published reports of diphenidine being sold in combination with other research chemicals, particularly synthetic cannabinoids and stimulants in Japanese herbal incense blends.

[17] A herbal incense sold in the Shizuoka Prefecture under the name "Aladdin Spacial [sic] Edition" was found to contain diphenidine and 5F-AB-PINACA at concentrations of 289 mg/g and 55.5 mg/g, respectively.

[15] Most recently diphenidine consumed in conjunction with three substituted cathinones, three benzodiazepines, and alcohol was implicated in a fatal ingestion of "bath salt" and "liquid aroma" products in Japan.