Long-Lasting Cognitive and Physical Impairment After Recreational Use of the Semisynthetic Cannabinoid Hexahydrocannabinonyl (HHC-C9): A Case Report.

Background and Clinical Significance: The recreational use of semisynthetic cannabinoids (SSCs) is increasing, and SSCs account for more than 40% of all new substances reported at the European level. Although designed to mimic the effects of tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis, evidence suggests that certain SSCs may elicit stronger, prolonged and unintended pharmacological effects. SSCs are easily accessible, particularly via online retailers, but in some countries, SSCs are also sold in convenience stores or specialty stores selling legal low-THC or cannabidiol (CBD) products. Often, SSCs are sold as "legal highs" and are found in various forms, including herbal mixtures (spice), vape products, and edibles such as cookies and candies, specifically targeting young users, including children. The products are frequently mislabeled and sold as souvenirs or aromatic potpourri to bypass regulations. Case Presentation: We present a case of a male in his early forties who was admitted to the Emergency Department due to noticeable deficits in alertness and responsiveness after recreational ingestion of two cannabis cookies labeled to contain 40 mg "CC9" and a bite of a gummy with unknown contents. The patient experienced vomiting and visual problems, and suffered from nine days of cognitive and physical impairment. HHC-C9, a novel SSC, was detected in blood through forensic toxicological analysis. Conclusions: Recreational use of HHC-C9 can cause vomiting, visual disturbances, and drowsiness, potentially requiring hospital treatment. Potency, clinical effects, and toxicity of SSCs can vary significantly, and in combination with easy accessibility, SSCs pose a potential risk of intoxication to unaware consumers.