Ipecac

Ipecac is a purple-tinted drug in liquid form which, when ingested, causes severe gastric distress in humans. Ipacac is easy to conceal, and appears to dissolve very quickly in room-temperature liquids.

Ipecac was used by Doctor Julian Bashir to poison a drink in a holosuite program in Quark's on Deep Space 9, part of an elaborate ruse staged by station personnel to defeat a jack-in-the-box subroutine planted in the "Vic's lounge" holoprogram by its creator, Felix. (DS9: "Badda-Bing, Badda-Bang")

In present-day medicine, ipecac (often called "syrup of ipecac") is used to induce vomiting.