Head lice infestation, medically known as pediculosis capitis, is a common problem that primarily affects children but can spread easily within households. Head lice are small, wingless insects that live on the human scalp and feed on blood. When faced with an outbreak, many people search for quick, inexpensive solutions, leading to the popular but unproven use of household products. This trend often includes applying mouthwash to the hair and scalp as a do-it-yourself treatment.
Does Mouthwash Kill Head Lice?
Mouthwash is not a reliable or recommended method for eliminating head lice or their eggs (nits). The belief that it works stems from ingredients like alcohol and essential oils (eucalyptol, menthol, and thymol), which have antiseptic properties. Some people theorize that the high alcohol content (up to 27% in certain brands) might suffocate or poison the live adult lice.
However, even if mouthwash kills some adult lice, its effect on nits is minimal. Nits are protected by a hard, waxy shell that resists penetration by most topical liquids. The eggs remain viable, continuing to hatch days later and leading to a renewed infestation. Successful treatment requires eliminating both the live insects and the unhatched nits.
The oils in mouthwash may temporarily loosen the cement-like substance that glues nits to the hair shaft, making mechanical removal slightly easier. This is often the actual mechanism behind any perceived success, rather than the mouthwash actively killing the parasites. Relying on this method alone is highly ineffective because it fails to address the entire life cycle of the head louse.
Safety Concerns of Using Mouthwash for Lice
Applying mouthwash to the scalp carries significant safety risks because it is not formulated for use on the skin. The high concentration of alcohol is highly irritating to the sensitive scalp. Leaving it on for extended periods can cause severe contact dermatitis, burning, or chemical irritation.
If the scalp is scratched or compromised from itching, the alcohol can cause intense pain or chemical burns. Accidental exposure to the eyes is a major concern, potentially causing severe irritation or damage. Furthermore, mouthwashes with high alcohol content are flammable, presenting a serious fire hazard if an electrical heat source, such as a blow dryer, is used.
The potential for systemic absorption is another factor, particularly in children. Prolonged contact increases the risk of these substances entering the bloodstream. Using a product for an unapproved purpose introduces preventable health complications.
Recommended Treatments for Head Lice
Effective treatment for head lice involves using approved products and combining them with thorough manual removal. There are two primary categories of effective treatments: over-the-counter (OTC) and prescription medications.
OTC products typically contain insecticides derived from pyrethrins or their synthetic counterpart, permethrin. Pyrethrins, which come from the chrysanthemum flower, and permethrin work by disrupting the nervous system of the lice, leading to paralysis and death. Because these products do not reliably kill all nits, a second application is generally required seven to ten days later to eliminate newly hatched lice before they can lay new eggs.
For cases where lice have become resistant to OTC treatments, a healthcare provider can prescribe stronger medications. Prescription options include benzyl alcohol lotion, which works by asphyxiating the live lice, and malathion, an organophosphate that is pediculicidal and partially ovicidal. Ivermectin and spinosad are also available as topical lotions and are often effective as a single-application treatment, with some formulations not requiring nit-combing.
Regardless of the chemical treatment chosen, mechanical removal with a fine-toothed nit comb is a necessary component of eradication. The wet-combing method involves applying hair conditioner to wet hair to immobilize the lice. The hair is then methodically combed from root to tip in small sections to physically remove both the lice and the nits. This process should be repeated every few days for several weeks to ensure all newly hatched lice are removed before they mature.