Failure of activated charcoal to reduce the release of gases produced by the colonic flora

Am J Gastroenterol. 1999 Jan;94(1):208-12. doi: 10.1111/j.1572-0241.1999.00798.x.


Objective: Activated charcoal is used to treat excessive volume or malodor of intestinal gas. Our previous studies demonstrated that activated charcoal failed to bind appreciable quantities of the volumetrically important gut gases. However, the odor of feces and flatus derives primarily from trace quantities of sulfur-containing gases, primarily H2S and methanethiol, which should avidly bind to activated charcoal. The goal of this study was to determine if ingestion of activated charcoal reduces the fecal release of sulfur gases.

Methods: Five healthy human volunteers ingested 0.52 g of activated charcoal four times daily for 1 wk and the fecal liberation of intestinal gases was measured before and after the activated charcoal treatment. In an effort to explain the in vivo results, additional in vitro studies were performed to compare the binding capacity of charcoal to the sulfur gas released by feces.

Results: Ingestion of activated charcoal produced no significant reduction in the fecal release of any of the sulfur-containing gases, nor was total fecal gas release or abdominal symptoms significantly influenced. In vitro studies suggested that the failure of ingested charcoal to reduce liberation of sulfur gases probably is explained by the saturation of charcoal binding sites during passage through the gut.

Conclusion: Commonly employed doses of activated charcoal do not appreciably influence the liberation of fecal gases.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bacteria / metabolism*
  • Charcoal / pharmacology*
  • Colon / microbiology*
  • Feces / chemistry*
  • Female
  • Flatulence / physiopathology
  • Gases / analysis*
  • Humans
  • Hydrogen Sulfide / analysis
  • In Vitro Techniques
  • Male
  • Middle Aged
  • Sulfhydryl Compounds / analysis
  • Sulfides / analysis*


  • Gases
  • Sulfhydryl Compounds
  • Sulfides
  • Charcoal
  • methylmercaptan
  • dimethyl sulfide
  • Hydrogen Sulfide