Swallowing hydrogen peroxide (H2O2) is harmful, and the severity of the danger depends directly on the concentration ingested. H2O2 is a simple chemical compound used widely as an oxidizer and antiseptic. It is highly reactive within the body, decomposing rapidly and causing damage to internal tissues. Risks range from mild gastrointestinal irritation to life-threatening complications, depending on whether a person swallows a common household dilution or a concentrated industrial solution.
Understanding Different Hydrogen Peroxide Strengths
Consumers most frequently encounter hydrogen peroxide in a dilute 3% solution, which is commonly sold in brown bottles for use as a first-aid antiseptic. This low concentration is also sometimes used in teeth whitening products or as a mild household disinfectant. Solutions used for hair bleach are slightly stronger, typically ranging between 6% and 10%.
The higher concentrations found in industrial, cosmetic, or specialized applications pose a much greater health risk. “Food grade” hydrogen peroxide, despite its misleading name, is often sold at 35% concentration and is extremely dangerous if ingested undiluted. The potential for serious harm increases dramatically as the percentage of H2O2 rises, shifting the substance from a mild irritant to a corrosive poison.
How Ingestion Harms the Body
Ingestion causes injury through two primary and distinct mechanisms within the digestive tract. First, the compound acts as a powerful oxidizing agent, directly causing corrosive chemical burns to the tissues it contacts. This oxidative damage can severely injure the mucous membranes lining the mouth, esophagus, and stomach.
The second, and often more dangerous, mechanism involves the rapid release of oxygen gas. Hydrogen peroxide instantly reacts with the enzyme catalase, which is abundant in human tissues, splitting the H2O2 molecule into water and a large volume of oxygen gas. For example, one milliliter of the common 3% household solution can liberate about ten milliliters of oxygen gas upon contact with tissue.
This rapid gas production causes significant internal pressure and foaming, leading to acute gastric distension, or stomach swelling. If the ingested solution is highly concentrated, the sheer volume of gas released can potentially cause the stomach wall to rupture. Oxygen bubbles can also be forced into the small blood vessels of the stomach lining, leading to a gas embolism. This condition occurs when gas bubbles travel through the bloodstream, potentially blocking blood flow to organs like the brain or heart, resulting in severe neurological damage or cardiac arrest.
Recognizing Symptoms and Seeking Medical Help
The symptoms following hydrogen peroxide ingestion can be immediate and alarming, particularly with higher concentrations. Observable signs include severe vomiting, abdominal pain, and stomach swelling due to the buildup of oxygen gas. A person may also experience difficulty breathing, chest pain, and chemical burns around the mouth or throat.
The immediate priority following any ingestion of hydrogen peroxide is to call the national Poison Help Hotline at 1-800-222-1222 or contact emergency medical services. Do not try to induce vomiting, as this can expose the esophagus to the corrosive chemical a second time, worsening the injury. For small ingestions of household 3% solution, a few sips of water or milk may be advised by Poison Control to help dilute the substance.
Any suspected ingestion of concentrated solutions, or if the individual displays symptoms like difficulty breathing or confusion, requires immediate professional medical evaluation. Imaging studies may be necessary to check for gas bubbles in the bloodstream, a complication that requires specialized treatment to resolve. Prompt medical attention is necessary to monitor for potential internal burns and the development of a gas embolism.