How is activated charcoal used clinically?

Adults usually receive 50 to 100 g; children 1 g per kg weight. These rules of thumb assume the typical adsorptivity of 900 m2/g (the availbale preparation at the time). Thus a 1 year old would get 10 g, a two year old 12.5 g,  a three year old 15 g, a four year old 17 g, and a five year old 19 g. If the amount of toxin is accurately known (which is not usually the case), dosing can also be calculated using a 10 to one ratio. For example, an ingestion of 6 g of aspirin would be treated with 60 g of activated charcoal.

For those patients admitted due to serious poisonings, activated charcoal is often given every 4 - 6 hours until the patient stabilizes. This improves the chances that the poison within the gastrointestinal tract will stay bound to charcoal until excreted. It also provides an additional mode of elimination called "intestinal dialysis" - that is, the presence of activated charcoal in the bowel promotes the transfer of toxin from the bloodstream into the charcoal within the bowel for excretion.

Does activated charcoal have any side-effects?

The downside of activated charcoal is practically non-existent. Activated charcoal itself is non-toxic. One cannot overdose on it . Following ingestion of activated charcoal, the mouth and stools are transiently black. Some constipation with multiple doses can occur; actual bowel obstruction is exceedingly uncommon. There have been rare reports of serious complications of charcoal therapy such as aspiration. This is usually seen in charcoal administered by tube in a less than conscious or uncooperative patient without a protected airway. 

What is the problem with the currently available preparations?

Palatability. Despite earnest attempts to improve palatability, all commonly used products (suspensions in the US) are administered as a black gritty liquid bearing a striking resemblance to old crankcase oil. In a small 1987 study by Grbcich et al "Administration of Charcoal in the Home" (an abstract in Vet. Hum. Toxicology 29, 458.), 6 children from 1-5 years of age were given 1 gm/kg of charcoal for ingestions not requiring a visit to the hospital. None took the full amount; one took 50%. "All parents had considerable difficulty getting the child to drink the charcoal and most indicated they would not choose this method of oral decontamination in the event of a future poisoning." There are also problems getting healthcare providers to administer it to children. The charcoal is often spit out, staining everyone and everything in its path. Many techniques have been used to trick the child, with varying degrees of success. One cannot just mix anything with the charcoal to mask its unpleasant characteristics - many substances diminish its effect.  It is fair to say that healthcare providers consider themselves fortunate if the child takes any charcoal.