1SB-LSD, or 1BS-LSD, also known as 1-(4-(trimethylsilyl)benzoyl)-LSD, is a psychedelic drug of the lysergamide family related to lysergic acid diethylamide (LSD). It is thought to be a prodrug of LSD. The drug was encountered online as a novel designer drug in September 2025. 1SB-LSD has been sold in the form of blotter containing 165üg per tab. It is the derivative of 1Bz-LSD (SYN-L-018) in which there is a 4-trimethylsilyl group on the benzyl ring. 1SB-LSD is not an explicitly controlled substance in the United States or in Canada.