Dragon's Blood is a highly addictive drug that is exported by Droaam. It is illegal in the Five Nations, but it is nevertheless smuggled into Sharn and other major cities.
Dragon's Blood is not literally the blood of dragons. It derives its name from its power to enhance the innate magical abilities of sorcerers and those with dragonmarks. The nature of the drug is a mystery, it is produced by the hags of Droaam (specifically Sora Katra and Sora Jabra) and uses a component that has yet to be identified; without this component, it is impossible to create.
The drug comes in three varieties at current: black, blue, and red dragon's blood. Each variety is more potent than the last, with black being the most diluted form of the drug, and red being the most concentrated. On top of the strength of the effect of the drug, the risk of overdose also increases as the potency does, every dose of red dragon's blood carries the risk of immediate death for most people. Even so, for some, the potential gain is worth the risk.