The use of hydrogen peroxide as a nasal spray is controversial. Some alternative medicine practitioners recommend its use; however, traditional medical texts argue against exposing mucous membranes to hydrogen peroxide. According to Princeton University, hydrogen peroxide or H2O2 is "a viscous liquid with strong oxidizing properties; a powerful bleaching agent; also used in aqueous solutions as a mild disinfectant and in strong concentrations as an oxidant in rocket fuels." Hydrogen peroxide is known to be a caustic chemica, and its caustic character increases with concentration.
Dilute, or 3 percent Hydrogen peroxide is available for home use. Concentrations of 3 to 10 percent or higher are used for industrial purposes. In the home hydrogen peroxide is used for external purposes such as washing out blood stains, as a disinfectant, deodorant or hair bleaching agent. It is sometimes used to clean superficial skin scrapes and bruises. At a concentration of 3 to 5 percent, hydrogen peroxide is mildly irritating to the skin and mucous membranes. Concentrations of 10 percent, which is common for hair bleaching, is caustic to skin and mucous membranes.
Any fluid or mist sprayed into the nose, which anatomically is a part of the upper respiratory tract, can be aspirated into the lungs. Aspiration of oral secretions can cause aspiration pneumonia. Nasal irrigation with a dilute substance with caustic potential such as hydrogen peroxide can likewise cause an aspiration scenario, causing lower airway damage. Problems such as a deviated nasal septum may add to this risk. Risk increases with the volume of hydrogen peroxide being used to irrigate the nose, and increased frequency of use.
The Agency for Toxic Substances and Disease Registry or ATSDR states: "Inhalation of vapors, mists, or aerosols from concentrated solutions of hydrogen peroxide can cause significant morbidity." Clinical manifestations of respiratory exposure to concentrated hydrogen peroxide are upper airway irritation, inflammation of nasal membranes, hoarseness, burning sensation or tightness in the chest. Respiratory exposure to high concentrations of hydrogen peroxide can cause severe mucosal congestion of the trachea and bronchi followed by accumulation of fluid in the lungs.
Hydrogen peroxide interacts with the enzyme catalase, releasing water and oxygen. The release of water and hydrogen constitutes the decomposition of hydrogen peroxide. 1 cc of 3 percent hydrogen peroxide releases 10 ml of oxygen. If the rate of oxygen release exceeds the maximum solubility in the blood, venous embolism occurs. It is conceivable that chronic use of 3 percent hydrogen peroxide for nasal irrigation can yield a risk of chronic aspiration, and resultant venous embolism. Chronic lung exposure can cause partial or complete collapse of the lung.
Substances used to irrigate nasal passages can also be swallowed. Oral ingestion of 3 percent hydrogen peroxide can result in gastric irritation, gastric distention, and vomiting. Higher concentrations can result in burning of all exposed tissues. Children may be particularly vulnerable to adverse effects of nasal irrigation with hydrogen peroxide because of their airways have smaller diameters.