Continuing Education Activity

Activated charcoal is a gastrointestinal adsorbent used in the management of acute oral poisoning and overdose. Activated charcoal binds to several drugs and toxins in the gastrointestinal tract, thereby reducing systemic absorption and limiting toxicity. Activated charcoal is most effective when administered soon after ingestion, although later administration may be beneficial in selected cases involving delayed absorption. This activity reviews the pharmacology, indications, contraindications, administration, adverse effects, drug interactions, and monitoring parameters associated with activated charcoal. Particular attention is given to patient selection, timing of administration, dosage, formulation type, airway protection, aspiration risk, and other safety considerations. This activity also highlights the importance of interprofessional collaboration among healthcare professionals to ensure the safe administration of activated charcoal and to optimize clinical outcomes in patients with poisoning.

Objectives:

• Identify the indications for activated charcoal use in patients with acute oral poisoning or overdose.
• Screen patients for contraindications to activated charcoal administration, including impaired airway reflexes, aspiration risk, bowel obstruction, and gastrointestinal perforation.
• Select the appropriate activated charcoal formulation, dose, and route of administration based on patient factors and the ingested toxin.
• Collaborate with interprofessional healthcare providers to monitor treatment response, adverse effects, and the need for additional interventions after activated charcoal administration.

Indications

An oral suspension of activated charcoal may be considered in cases of poisoning when gastrointestinal decontamination is indicated, and the clinician can administer it within 1 hour of ingestion. Contraindications (see below) should be carefully evaluated before initiating activated charcoal treatment.[1][2][3] Although activated charcoal has been shown to significantly reduce the absorption of many ingested toxins when administered within the first hour after ingestion, no studies have demonstrated improvements in patient-oriented outcomes, such as mortality, morbidity, or length of hospital stay, with its use.[4]

Observational trial data in recent years suggest that single-dose activated charcoal (SDAC) may significantly reduce drug absorption and bioavailability under the following circumstances:

• Anticipation of serious toxicity, such as after an acute toxic ingestion of acetaminophen. 
• Toxin ingestion within 1 hour before administration, as reductions in absorption beyond 1 hour are generally unlikely to be clinically meaningful, except in the situations noted below.
• Activated charcoal administration within 4 hours of a large ingestion, ingestion of a delayed-release formulation, or ingestion of a substance with anticholinergic or opioid properties that reduce intestinal motility, in which case activated charcoal may still be beneficial.[5][6]
• The patient is alert and cooperative.
• Airway reflexes are intact, or the airway is protected with an endotracheal tube.
• The ingestion involves a toxin for which there is no specific antidote.
• The ingested toxin is known to be adsorbed by charcoal (see below).

Multiple-dose activated charcoal (MDAC) is often considered in cases of life-threatening ingestion of carbamazepine, dapsone, phenobarbital, phenytoin, quinine, valproic acid, and theophylline.[7][8] Hatanaka K et al. reported 2 cases of lamotrigine overdose treated with multiple doses of activated charcoal. The investigators believed that the activated charcoal treatment shortened the elimination half-life of lamotrigine by reducing enterohepatic recirculation.[9] Störmann S et al. reported a case involving a suicidal patient who ingested a large dose of chloroquine and diazepam.[10] The patient received treatment with activated charcoal, vasopressors, and diazepam and survived.

Maes K et al. reported a case involving a suicidal patient who ingested Digitalis purpurea (Foxglove) leaves.[11] The patient was initially treated with digitoxin-specific Fab fragments. Multiple doses of activated charcoal were then administered to reduce absorption and enterohepatic recirculation of cardiac glycosides, such as digoxin, from Digitalis purpurea leaves in the gastrointestinal tract.[11] Ajjampur and Subramaniam reported a case involving a suicidal patient who ingested a toxic dose of caffeine. The patient was treated with a beta-blocker and activated charcoal and survived.[12] An unlabeled use for activated charcoal is the treatment of inadvertent gluten ingestion by patients with celiac disease. However, there is a lack of clinical evidence to support this use.[13]

Outside of clinical settings, activated charcoal has gained popularity as a food additive, primarily for its distinctive black color in foods and beverages and its purported earthy flavor. In addition, it is also marketed for alleged health benefits, including use as a “cleanse” for generalized corporeal toxins. Although many companies consider activated charcoal generally safe, it is not specifically listed nor recognized under sections 201(s) and 409 of the Federal Food, Drug, and Cosmetic Act [FDA, GRAS]. Furthermore, activated charcoal is not currently approved as a food additive by the US Food and Drug Administration (FDA) under 21 CFR, Part 184 [Inventory of Food Contact Substances Listed in 21 CFR].

The Association of Food and Drug Officials has asked the FDA to review the use of activated charcoal in foods and beverages because of several safety concerns. Individuals who regularly consume products containing activated charcoal may be at risk for reduced effectiveness of routine medications, nutrient deficiencies related to activated charcoal’s binding to vitamins, minerals, and antioxidants, and adverse effects such as constipation. Consumers are often unaware of these risks because there are currently no specific informative requirements addressing these concerns [Association of Food and Drug Officials [2019 Resolution 1: Charcoal aka Activated Carbon Used as a Food or Beverage Ingredient].

Mechanism of Action

Activated charcoal adsorbs ingested toxins in the gastrointestinal tract, preventing their systemic absorption. Activated charcoal adsorbs toxins only in the dissolved liquid phase via direct contact. Orally administered activated charcoal does not get absorbed through the gastrointestinal tract and remains in its unchanged form within the gut lumen. Ingested toxins may come into contact with activated charcoal if they have not yet been absorbed from the gastrointestinal lumen, or if the toxin is recirculated into the gut lumen via enterohepatic or enteroenteric recirculation through active secretion or passive diffusion.

Activated charcoal adsorption of toxins is based on an equilibrium between the free toxin and the activated charcoal-toxin complex. Desorption of the toxin from activated charcoal may occur. However, in the presence of an adequate dose of activated charcoal, the equilibrium shifts toward the activated charcoal-toxin complex. This attempt to shift the equilibrium in favor of activated charcoal-toxin complexes is the rationale for dosing activated charcoal at a 10:1 activated charcoal-toxin ratio (see below).

Activated charcoal adsorbs toxins most effectively in their nonionized forms. Polar, water-soluble molecules are less likely to be adsorbed. Due to the pharmacodynamics of activated charcoal, it most effectively adsorbs nonpolar, poorly water-soluble organic toxins.[14]

Most ingested toxins will have decreased systemic absorption in the presence of activated charcoal, including acetaminophen, aspirin, barbiturates, tricyclic antidepressants, theophylline, phenytoin, and most inorganic and organic materials.[15][16][17] Notably, activated charcoal does not effectively adsorb alcohols, metals such as iron and lithium, electrolytes such as magnesium, potassium, or sodium, and acids or alkalis due to the polarity of these substances.

Pharmacokinetics

Absorption: Activated charcoal is not absorbed from the gastrointestinal tract.

Elimination: Activated charcoal is excreted in the feces.

Administration

Available Dosage Forms and Strengths

Formulations have been developed to improve the palatability of activated charcoal, which has a gritty texture. Ready-to-use aqueous suspensions are available in 15 g, 25 g, and 50 g formulations, including premixed products containing sorbitol. If activated charcoal is not available in a premixed formulation, a slurry may be prepared by mixing it with a suitable liquid, such as water, cola, or flavored syrup, in a 1:8 ratio. Palatability may be improved by serving the mixture in an opaque cup with a lid and a straw.

Table

Table. Available Activated Charcoal Oral and Reconstituted Suspension Formulations.

Liquid: The suspension should be shaken thoroughly for at least 30 seconds before administration to ensure uniformity.

Powder: The powder should be reconstituted with water using at least 8 mL/g of charcoal, corresponding to an approximate charcoal-to-water ratio of 1:4 to 1:8, and mixed vigorously to form a slurry (eg, 25 grams in approximately 120 mL of water or 50 grams in approximately 240 mL of water).

Storage and stability: Activated charcoal readily adsorbs gases from the environment and should be stored in a tightly sealed container.

Adult and Pediatric Dosages

Clinicians should administer activated charcoal when the ingested toxin is believed to remain within the gastrointestinal tract and when the potential benefit of reducing absorption outweighs the risks of treatment. The optimal dose of activated charcoal has not been established. Activated charcoal may be administered orally or through a nasogastric or orogastric tube. When the amount of ingested toxin is known, experts generally recommend an activated charcoal-to-toxin ratio of 10:1. However, this ratio may be impractical in cases involving large ingested doses of a toxin.[18]

When the amount of toxin ingested is unknown, or when achieving a 10:1 activated charcoal-to-toxin ratio is impractical in large ingestions, SDAC should be administered at 1 g/kg of body weight or according to the following age-based dosing recommendations:

• Adults: 50 to 100 g
• Infants aged 1 and younger: 10 to 25 g
• Children aged 2 to 12: 25 to 50 g
• Children aged 12 or older: Adult dosing should be followed

MDAC refers to the administration of 2 or more sequential doses of activated charcoal to enhance the elimination of an ingested toxin. MDAC appears to reduce ongoing absorption of toxin remaining in the gastrointestinal tract and enhance elimination through enterohepatic or enteroenteric recirculation. Although the quality of clinical data is limited, MDAC is generally considered beneficial for potentially life-threatening ingestions of carbamazepine, dapsone, phenobarbital, quinine, and theophylline.

Dosing strategies for MDAC vary. Initial dosing is generally based on either a 10:1 activated charcoal-to-toxin ratio or 1 g/kg of body weight. Subsequent doses in adults typically range from 0.25 to 0.5 g/kg every 1 to 6 hours. In some cases, activated charcoal has been administered continuously through a nasogastric tube.

A simplified MDAC approach for adult patients includes:

• A loading dose of 25 to 100 g
• Repeat doses of 10 to 25 g every 2 to 4 hours

Due to the variability in proper dosing strategies and indications for MDAC administration, it would be reasonable to consult a regional toxicologist or Poison Control Center before initiating MDAC therapy.

Specific Patient Populations

Renal impairment: Activated charcoal does not need dose adjustments in renal impairment, as it is not absorbed into the system.

Pediatric patients: Guidance from the American Academy of Clinical Toxicology (AACT) indicates that activated charcoal should not be used routinely and is generally most appropriate when administered within 1 hour of ingestion. Current evidence does not clearly demonstrate improved clinical outcomes when it is administered later. When used, an activated charcoal-to-drug ratio of approximately 10:1 is suggested. In pediatric patients with an unknown amount ingested, dosing is typically 1 to 2 g/kg. The initial dose may be combined with a cathartic agent, such as sorbitol, to improve palatability and gastrointestinal transit. However, cathartics should not be included with repeated doses because of the risk of fluid and electrolyte disturbance.[19]

Pregnancy and breastfeeding considerations: As activated charcoal is not systemically absorbed, fetal and infant exposure during pregnancy and lactation is expected to be negligible. In general, decisions regarding antidotal therapy should prioritize maternal health and prognosis. When clearly indicated, activated charcoal and other antidotal treatments should not be withheld during pregnancy because of concerns about potential teratogenic risk.[20]

Adverse Effects

Pulmonary aspiration and resulting aspiration pneumonitis are the most concerning risks associated with the administration of activated charcoal. Aspiration from emesis and misplaced nasogastric tubes for activated charcoal administration can lead to severe respiratory compromise and even death. Therefore, an adequate airway assessment must occur before activated charcoal administration. In patients with a depressed level of consciousness, providers must consider the risk-to-benefit ratio of intubation for airway protection and the therapeutic benefits of activated charcoal. Emesis is more common with rapid administration of activated charcoal, and the risk of emesis increases when sorbitol is added. Patients should be monitored for mental status changes and continued airway protection if emesis occurs. 

Although emesis is a common adverse effect, more significant gastrointestinal complications such as bowel obstructions have been reported after the administration of activated charcoal. Patients with preexisting motility disorders, those receiving opioids or antimuscarinic drugs, and those treated with MDAC might be at greater risk. However, the likelihood of a more significant gastrointestinal complication following SDAC therapy is low.[4]

Drug-Drug Interactions

Activated charcoal may reduce the absorption and therapeutic effect of coadministered medications, including propranolol, rifampin, phenobarbital, and other orally administered agents. Routine use of sorbitol or other cathartics in combination with activated charcoal is not advised.

Contraindications

The manufacturer does not list any formal contraindications for activated charcoal use. However, a 2005 position statement from the AACT identifies the following contraindications and relative contraindications:

• Patients with an unprotected airway, such as those with a depressed level of consciousness, and without endotracheal intubation.
• Situations in which activated charcoal may increase the risk or severity of aspiration, such as ingestion of hydrocarbons with high aspiration potential.
• Conditions associated with a high risk of gastrointestinal perforation or hemorrhage, including certain medical conditions or recent gastrointestinal surgery.
• Circumstances in which endoscopy is likely to be required, because activated charcoal may obscure endoscopic visualization.
• Presence of an intestinal obstruction.
• Ingestion of substances that are not meaningfully adsorbed by activated charcoal, including metals, acids, alkalis, electrolytes, and alcohols.

MDAC is relatively contraindicated when decreased gastrointestinal motility is expected, such as after ingestion of opioids or anticholinergic agents. If MDAC is used in these patients, close monitoring is required for obstruction and aspiration.

Monitoring

As activated charcoal remains inactive in the gastrointestinal tract, no therapeutic index for systemic absorption is applicable.

Toxicity

No significant toxicity from activated charcoal is expected as it is not absorbed systemically; however, adverse effects from its administration, such as emesis, aspiration, and bowel obstruction, may occur.

Enhancing Healthcare Team Outcomes

Activated charcoal is commonly used in emergency departments for the treatment of toxic ingestions. When administered soon after ingestion, it can significantly reduce the absorption of many drugs and toxins. However, evidence demonstrating improvement in patient-oriented outcomes remains limited, and activated charcoal administration carries potential risks, including aspiration and gastrointestinal complications. Healthcare professionals in the emergency department, including nurses, pharmacists, and physicians, should understand the appropriate indications, timing, dosing, and risks associated with the use of activated charcoal. Because activated charcoal is also marketed in health food stores for various unregulated purposes, patients should be educated about the potential risks associated with its unregulated use.[4][21]

Clinicians considering the use of activated charcoal should consult a clinical pharmacist, toxicologist, or Poison Control Center when there is uncertainty regarding its appropriateness. These resources can also provide guidance on dosing and administration. Nurses are responsible for administering activated charcoal, monitoring for adverse effects, and assessing the effectiveness of the intervention. Clear communication among healthcare team members and documentation of interventions and patient responses are essential. An effective interprofessional approach can help optimize outcomes in patients with toxic ingestions.

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Disclosure: Alan Taylor declares no relevant financial relationships with ineligible companies.

Disclosure: Michael Galuska declares no relevant financial relationships with ineligible companies.

Disclosure: Preeti Patel declares no relevant financial relationships with ineligible companies.