Activated charcoal

What activated charcoal is

Activated charcoal is carbon with a porous structure and a very large internal surface. As a medicine it is called medicinal charcoal; the Kohle-Compretten approved in Germany contain 250 mg per tablet and, according to the prescribing information, are not pharmacy-only. As a food supplement and in drinks, activated charcoal is mostly sold with the promise of “detoxifying” the body.

In the BK-Score, human evidence stands at 6 out of 10 points. This axis rates the state of knowledge, not the substance: the binding effect has been measured in many controlled studies, whereas the clinical benefit in poisoning rests mostly on low-quality studies. The detox use with which activated charcoal is sold in the lifestyle sector has not been studied.

How it works

According to the prescribing information, medicinal charcoal adsorbs dissolved particles from liquids and gases as well as bacteria, bacterial toxins and other toxic substances on its porous surface. What is bound can no longer pass into the blood; the stool turns black in the process.

How strong the effect is depends on timing and amount. In the meta-analysis by Jürgens 2009, the reduction in drug absorption was greater the more charcoal was given relative to the drug (rho = 0.69), and it also depended on properties of the active substance. Not every substance binds: acids and alkalis, alcohols, organic solvents, inorganic salts and metals are captured poorly or not at all (Zellner 2019).

What the studies show

Drug binding: Jürgens 2009

Jürgens and colleagues pooled 64 controlled studies in healthy volunteers who received activated charcoal within 6 hours of a medicine. When given within 0 to 5 minutes, drug absorption fell by a median of 88.4 percent (p < 0.00001); when given up to 4 hours later, still by 27.4 percent. The charcoal was most effective immediately after ingestion and in large amounts.

Poisoning: systematic review by Hoegberg 2021

On behalf of the American, European and Asia-Pacific toxicology societies, Hoegberg and colleagues evaluated the literature up to the end of 2019: 296 human studies, 118 animal studies and 145 laboratory studies. 83 percent were of low or very low quality according to GRADE. The better studies mainly examined paracetamol, phenobarbital, carbamazepine, cardiac glycosides, ethanol, iron, salicylates, theophylline, tricyclic antidepressants and valproate. The review found no study on the best dosage. Many studies reported a benefit even when given after more than one hour; overall, the data were inconsistent.

Gout: Guo 2026

In a double-blind study with 348 gout patients, Guo and colleagues compared febuxostat 40 mg, febuxostat 20 mg alone and febuxostat 20 mg together with 4.5 or 7.2 g activated charcoal over 24 weeks. The primary endpoint, the proportion with uric acid below 360 µmol/l, was not reached more often with the combination. The combination did, however, reduce the number of gout attacks compared with both febuxostat groups, prolonged the time to the first attack and lowered LDL cholesterol. Adverse events were similarly frequent in all groups.

Detox in healthy people

We did not find a controlled study in Europe PMC that tests activated charcoal as a daily detox agent in healthy people. The available data concern specific situations: a known ingestion of a toxin, acute diarrhea, bloating after eating or individual conditions such as gout.

Where the data stop

• Everyday detox. For regular intake by healthy people there are neither efficacy nor long-term data. What the charcoal binds in the gut of a healthy person with daily intake has not been studied.
• Clinical benefit in poisoning. Binding is well measured; the effect on course and survival rests mostly on low-quality studies. According to Zellner 2019, there is no internationally valid guideline; administration is weighed case by case with the poison control center.
• Diarrhea. We did not find a more recent randomized trial on medicinal charcoal in acute diarrhea; its use relies on the marketing authorization under medicines law.
• Gout. There is a single study from China, and its primary endpoint, uric acid, was missed.

Status, approval and legal

Medicinal charcoal is approved as a medicine in Germany, for example as Kohle-Compretten 250 mg for acute diarrhea and for preventing absorption in oral poisoning; according to the prescribing information (as of April 2025), it is not pharmacy-only. For diarrhea, the prescribing information specifies 2 to 4 tablets 3 to 5 times daily for adults and adolescents aged 14 and over, until the stool normalizes. If treatment is unsuccessful after about 3 days, other measures are needed.

As a food, activated charcoal may be advertised with the authorized claim on bloating if a serving contains 1 g and the note on intake before and after the meal is included (Regulation 432/2012). The EU list contains no authorized claim on detoxification.

Safety

For diarrhea in the recommended amounts, no side effects are known according to the prescribing information; after very high doses in poisoning, constipation and bowel obstruction can occur in individual cases. Contraindications are febrile diarrhea and poisoning with strong acids or alkalis, because the charcoal obstructs endoscopy there. In emergency treatment, impaired consciousness without a secured airway is the most important contraindication, because the charcoal can be inhaled (Zellner 2019). According to the prescribing information, medicinal charcoal may be used during pregnancy and breastfeeding.

For everyday life, the binding of medicines matters most. According to the prescribing information, medicinal charcoal should not be given at the same time as other medicines, because their effect may be reduced. Anyone taking long-term medication should clarify the time interval with a pharmacy or a physician. In the BK-Score, safety stands at 7 out of 10 points; this axis measures how well safety has been studied, not how safe the substance is. This text is information and does not replace medical advice.

Sources

• Zellner T et al., Dtsch Arztebl Int 2019 – review on the treatment of poisoning with activated charcoal
• Hoegberg LCG et al., Clin Toxicol 2021 – systematic review, 296 human studies on toxin removal with activated charcoal
• Jürgens G et al., Clin Pharmacol Ther 2009 – meta-analysis, 64 controlled studies on drug binding in volunteers
• Guo K et al., Am J Med 2026 – double-blind study, 348 patients with gout
• Prescribing information Kohle-Compretten 250 mg tablets, Klinge Pharma, as of April 2025
• EFSA 2011 – assessment of the health claim on activated charcoal and excessive flatulence (EFSA Journal 2011;9(4):2049)
• Regulation (EU) No 432/2012 – list of permitted health claims made on foods