Hysteriat is a potent aphrodisiac drug manufactured in the Imperium of Sidhae, and is used mainly for recreational purposes. It is also occasionally used as a tool of torture in the hands of Imperial Judicators by inflicting extreme sexual arousal and then denying the victim release.

The drug greatly increases sexual desire and sensitivity to sexual stimulation, not unlike Frenkish soma, but is not otherwise known to have other mind-altering effects. Unlike soma, however, hysteriat is known to be highly-addictive - or rather, the effects of hysteriat rather than the substance itself cause heavy addiction. According to Serena Romana, who uses the substance on Zinoviya Marilova on several occasions in Access Violation, the addicts begin to crave nothing but more hysteriat-adled sex, neglecting even their basic needs like eating, sleeping or hydrating themselves, and eventually die of exhaustion and dehydration.

Hysteriat is described as an amber-coloured liquid and primarily applied intravenously by means of an auto-injector or syringe. It is also capable of being absorbed through the skin to somewhat lesser effect, as indicated by Alain using topically-applied hysteriat to seduce Sophie Bu in Blood Debt. The drug's legal status in the Imperium is never stated, though it is probably manufactured and distributed legally in limited quantities as a luxury commodity. Hysteriat is said to be very expensive, at least by ghetto-dwelling human standards - according to Mildred Boughton in Access Violation, nobody in Bayit Gadol ghetto can afford it, even her, a powerful gang boss, only having heard of it's existence.

Known users include Serena Romana, who uses hysteriat both for recreational and interrogation purposes in Access Violation, and Alain, who uses the substance recreationally in both Access Violation and Blood Debt on several occasions. Alain is mentioned to always carry several vials of hysteriat with him, stashed in the wrist-brace pouches normally reserved for plasma grenades for his Enforcers, and seems to use the drug to enhance the sexual experience of his numerous scores, though it is not known if he also uses the drug on himself.

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