evidence: Activated charcoal, or activated carbon, is an amorphous form of carbon prepared from incomplete combustion of carbonaceous organic matter. It is activated by an oxidizing gas flow at high temperature passed over its surface to make a fine network of pores, producing a material with large surface area and high affinity for various substances. It is used as a gastric decontaminant and emergency medication to treat poisonings following excessive oral ingestion of certain medications or poisons by absorbing most drugs and toxins. However its effects is rendered poor on some compounds including strong acids or bases, methanol and substances with limited absorptive capacity (including iron, lithium, arsenic). It works by binding to the poison in the gastric contents in a reversible fashion thus may be adminstered together with a cathartic to reduce the small intestine transit time. The clinical applications of activated charcoal occured in the early 1800's. While this management for acute poisoning is considered fairly invasive, it is on the World Health Organization's List of Essential Medicines that includes the most important medications needed in a basic health system.