Hydrogen Peroxide Toxicity

Etiology

When exposed to skin, dilute hydrogen peroxide - as is found in most households, can act as an irritant, and symptoms are generally mild. Symptoms are more significant when exposed to mucous membranes but are still mild. Ophthalmic exposure can be very painful and may cause local injury to the cornea or conjunctiva. Similarly, ingestion of dilute hydrogen peroxide also usually results in milder symptoms and generally presents with possible injury to the mucous membranes, abdominal pain, nausea, and vomiting. Toxicity from ingestion usually results from the release of oxygen gas when hydrogen peroxide comes into contact with catalase found in tissues.[2][7] 

More concentrated hydrogen peroxide solutions, often found in industrial strength solutions, cause significantly more severe damage with all types of exposures. As a concentrated solution, hydrogen peroxide is classified as caustic and can cause significant chemical burns. Ingestion of concentrated hydrogen peroxide may also cause burns to the mouth, throat, and esophagus, as with ingestion of other caustics. However, it will also release significant amounts of oxygen gas when exposed to the enzyme catalase, which is present in living tissue.[7][8][9] 

This gas is released both in the GI tract and in the bloodstream as hydrogen peroxide passes easily through biological membranes and crosses into nearby blood vessels. If introduced into the bloodstream directly, it releases oxygen gas and can cause significant air emboli, including possible cerebral emboli.[8][9][10][11]

Inhalation of hydrogen peroxide may cause severe issues due to tissue injury and airway irritation leading to potential airway compromise.[2] Finally, concentrated hydrogen peroxide may be cytotoxic due to lipid peroxidation.[3]

Epidemiology

Hydrogen peroxide poisoning tends to be bimodal, as most household chemical ingestions are. Toxicity occurs in both young children and adults. Young children tend to be exposed accidentally to household concentrations of hydrogen peroxide.

Adults tend to have more severe exposures either due to intentional ingestion of higher quantities or accidental exposure to higher concentrations in an occupational setting. Toxicity in children is less likely to cause significant mortality or morbidity than in adults as it is often lower concentration solutions, often accidental, and more likely to be a less dangerous mode of exposure (i.e., topical). However, toxicity occurs at a much lower volume due to smaller patient sizes.[12][13]

History and Physical

The patient’s presentation is going to depend on the type of exposure. Most topical exposures to dilute hydrogen peroxide have very mild symptoms and resolve quickly with just decontamination. Therefore, many will be unlikely to seek medical care. Higher concentration exposures may present with topical chemical burns, which can be severe. These most likely occur in occupational settings to adults who work in industrial settings, including paper and fabric industries, foam rubber, and rocket fuel.[2]

Ophthalmic exposures will present with tearing, conjunctival injection, and pain. Depending on underlying damage, they may have some vision loss, which may be temporary or permanent.[2]

Accidental ingestions will mostly occur in young children and present with nausea and vomiting. If a large amount of hydrogen peroxide is ingested, the patient may also present with altered mental status as the hydrogen peroxide may cross into the bloodstream and cause air embolization.[2]

Intentional ingestions are most likely to present in adults with either involve higher concentrations or larger amounts. They are also less likely to present early after the ingestion and therefore are more likely to have more severe symptoms such as gaseous distention, abdominal pain, nausea, vomiting, and symptoms of air emboli such as altered mental status, neurological changes, or hypotension. Gastrointestinal bleeding, secondary to the burning of the mucosa, air emboli, subsequent necrosis, or rupture from the rapid distension of the gastrointestinal tract, can also occur. Endoscopy is often required to evaluate and treat these ingestions fully.[8][9]

Occasionally, patients may present after direct introduction to the bloodstream. This can occur with aggressive irrigation of wounds, accidental IV administration, irrigation of surgical wounds, or similar situations. These patients will present with symptoms of air emboli or local gas production such as subcutaneous air, pain, and swelling as well as possible local tissue injury due to topical exposure or wound beds.[3][14]

Another unusual presentation is exposure to mucous membranes, such as during enemas or intraoperative irrigations. Some of these may also occur in the nasal or oral mucosa in inhalation injuries, ingestions, or gargling. Inhalation will also cause difficulty breathing and may lead to severe respiratory distress. Patients will likely present with wheezing, drooling, and/or stridor and may have subglottal narrowing on x-ray imaging.[2][15][16]

Evaluation

The history of any patient presenting with exposure should include what they were exposed to and the route. For hydrogen peroxide, the concentration, route of exposure, and location should be determined. This can help guide the physical exam and further evaluation. Ask about their symptoms, such as nausea, vomiting, difficulty breathing, or pain. It is also essential to ask about the timing of the exposure and potential co-ingestions or other exposures.[2]

The physical exam should begin with a close examination for soft tissue injury at the exposure site. This would include erythema of the skin, a whitish discoloration, and ulcers in the mouth. This would also include any evidence of airway compromise, including stridor, drooling, abnormal breath sounds, or swelling of the oropharynx or nasopharynx. A physical exam must also include searching for evidence of gas formation, such as subcutaneous emphysema or abdominal distention. A thorough neurologic exam should be performed due to the risk of air emboli.[2][12]

No specific levels are indicated for hydrogen peroxide toxicity itself. However, clinicians should consider obtaining lab work related to potential complications, such as a complete blood count for significant hematemesis, a metabolic panel, and cardiac enzymes to evaluate for e ischemia. You must also consider co-ingestions as accidental and intentional exposures may be at higher risk for exposure to other potentially toxic chemicals.[17][18]

Imaging should be performed if there is any concern for air embolization and should focus on the area of concern. CT scans or MRIs should be performed for neurological changes. This would include CT or MRI of the head and/or spine as any of these areas may be affected.[11][19][20] 

Imaging the chest with either X-ray or CT should also be performed for any concerns for mediastinal air or other air emboli, including air in the cardiac ventricles. Consider imaging of the abdomen or pelvis to evaluate inappropriate amounts of air in the GI tract or other potential air emboli, such as air in the portal system.[4]

Treatment / Management

Treatment depends heavily on the type of exposure and concentration of the solution. There is no antidote for hydrogen peroxide, and dialysis is ineffective. Dilute hydrogen peroxide is much less likely to cause significant symptoms, and many of these exposures may be safely observed at home. Ingestion of large amounts of dilute hydrogen peroxide may cause significant symptoms to bring patients to the emergency department. These may also be generally managed with symptomatic management.

Caregivers can consider a nasogastric tube to drain the stomach if the patient presents early enough. This may also help decompress the GI tract and make the patient more comfortable. Nausea and vomiting are the most common presenting symptoms with these types of exposures, and emesis will often be foamy.[12]  (B2)

As with other topical exposures, the first treatment will be decontamination. Remove any clothing soaked with hydrogen peroxide. Rinse the area with copious amounts of water or normal saline. If a patient presents after ophthalmic exposure, be sure to remove contact lenses if present. Proceed with irrigation with copious amounts of normal saline.[2] Evaluate for corneal injury using fluorescein and slit lamp if available. Close follow-up with ophthalmology after injury should be encouraged for further treatment of any corneal injury. Treatment for corneal injury is similar to other corneal or conjunctival injuries.[21](B3)

If exposure involves more concentrated solutions, initial treatment remains decontamination -- if possible. However, symptoms are more likely to be more severe, and patients may require more significant interventions. Early intubation is necessary if there is any concern for airway compromise, as tissue damage is likely to progress and progress rapidly.[22][23]

Patients with signs or symptoms of significant air emboli need to obtain relevant imaging quickly. If there is air in the mediastinum or heart, or the patient is hypotensive, and there is suspicion o significant air emboli, place patients in the Trendelenburg position to help prevent blockage of the right ventricular outflow tract by intravascular gas.[24] (B3)

Clinicians should consider hyperbaric therapy in symptomatic patients with evidence of air emboli.[4][8][25][26] In very severe cases, patients may require central line placement to allow for the removal of air from the major blood vessels or right ventricle.[24](B3)

Differential Diagnosis

Differential diagnoses also depend on the type of exposure. Less significant ingestions may present with abdominal pain, nausea, and vomiting and appear similar to gastroenteritis, pancreatitis, other toxic ingestions, or other more common causes of gastric upset.[12]

Inhalation injuries may present with mild to severe respiratory distress or dyspnea. They may present similarly to asthma exacerbations, other types of inhalation injuries, respiratory infections, or anaphylactic or other allergic reactions.[15][16]

More significant ingestions or exposure directly into the bloodstream from injection or aggressive wound irrigation may present with altered mental status, coma, hypoxia, and hypotension. The differential diagnosis in these cases may be broad if no other history is available. Fortunately, the evaluation for patients presenting with these severe symptoms will likely include imaging or lab work that would lead to the diagnosis of hydrogen peroxide toxicity, presuming the treating provider is aware of the risks and presentation of such exposures.[27][28]

Prognosis

Prognosis depends on the type of exposure and concentration of the solution. Topical and ophthalmic exposures are likely to have a very good prognosis, regardless of the concentration.[13][21] However, more concentrated solutions may cause chemical burns, and the recovery from these burns depends on the depth of tissue injury, the location of the injury, and the surface area involved. There may be associated complications, including increased mortality and morbidity if tissue injury covers a large surface area or involves a joint. Corneal scarring may also occur if the eye is involved and significant corneal injury occurs.[21]

Inhalation injuries often present with mild symptoms, but more severe injuries require early intervention. Again, the prognosis is quite good if presenting with only mild symptoms. The prognosis remains fair to good if the patient presents with more severe symptoms and early intervention is taken.[16] However, chronic exposure may lead to chronic interstitial lung disease or other chronic lung diseases.[29]

Ingestions have an extremely variable prognosis depending on the concentration of the solution and the amount ingested. The prognosis for ingestion of relatively small amounts of a dilute solution is extremely good, and these patients can be safely observed at home.[13] 

Ingestion of larger amounts of dilute hydrogen peroxide or small amounts of more concentrated hydrogen peroxide can have a much poorer prognosis, especially if air embolization has occurred. Even small amounts of concentrated hydrogen peroxide can be lethal in certain situations. For example, a 2-year-old boy presented after accidental ingestion of about 120 to 180 mL of 35% hydrogen peroxide. An antemortem chest X-ray revealed air in the mediastinum and the entire right ventricle. He presented in extremis and unfortunately did not survive.[24] 

Another fatal ingestion involved a 2-year-old female who accidentally ingested "2 sips" of 35% hydrogen peroxide while visiting a dairy farm. On autopsy, she was found to have diffuse alveolar damage, erosion of the trachea, and gaseous distention of mucosal membranes in the gastrointestinal and respiratory tract.[30]

Complications

Topical injuries will likely heal with no permanent damage. However, if there are severe chemical burns, the patient should be treated as any other burn patient. They will also be at risk for any of the complications seen in other burn patients, such as scarring, dehydration due to fluid losses, and infections. Ophthalmic injuries may cause severe burns and lead to temporary or permanent vision loss.[21]

Ingestion can lead to scarring of the esophagus or throat, which may lead to strictures and other similar complications.[31][32] If the hydrogen peroxide was absorbed or directly introduced into the bloodstream, air emboli might have formed and caused tissue necrosis. This can lead to various effects depending on where the emboli occurred. The patient may have permanent neurological damage or even death. There have been cases of multiple cerebral emboli that have led to severe and permanent disability, as seen in strokes.[33][34]