Lacing or cutting, in drug culture, refer to the act of using a substance (referred to as the lacing agent or cutting agent) to adulterate substances independent of the reason. The resulting substance is laced or cut.
Some street drugs are commonly laced with other chemicals for various reasons, but it is most commonly done to bulk up the original product or to sell other, cheaper drugs in the place of something more expensive. Individuals sometimes lace their own drugs with another substance to combine or alter the physiological or psychoactive effects.