Borax, or sodium tetraborate, is a naturally occurring mineral salt often found in cleaning products and certain pesticides. It is known for its cleaning and abrasive properties. When dealing with pests, people often wonder if this readily available substance is an effective solution for head lice infestations, or Pediculosis capitis. The question of whether borax kills the parasites and if it is safe for the human scalp determines why health organizations do not recommend it for treating lice.
The Claimed Efficacy Against Lice
The idea that borax can eliminate head lice stems from its known use as an insecticide against household pests like ants and cockroaches. Borax functions primarily as a stomach poison when ingested, disrupting insect digestive systems. It is also a desiccant, drawing moisture out of an insect’s body, leading to dehydration.
However, this mechanism does not translate effectively to human head lice. Lice are blood-sucking parasites that attach firmly to the hair shaft and feed exclusively on the scalp. Unlike crawling insects that ingest the powder, head lice are not exposed to borax in a way that allows for effective systemic poisoning or desiccation.
There is no clinical evidence supporting the use of borax as an effective treatment for human head lice. Treatments not specifically formulated for lice often fail to penetrate the protective shell of the nit (louse egg), allowing the infestation to return once the eggs hatch. The lack of regulatory approval from bodies like the Centers for Disease Control and Prevention (CDC) or the Food and Drug Administration (FDA) confirms borax is not a viable solution.
The Human Toxicity of Borax Exposure
The primary reason borax is not a safe solution is its significant potential for human toxicity, especially when applied directly to the body. While borax is poorly absorbed through intact skin, a lice infestation often leaves the scalp irritated, scratched, or abraded. This damage compromises the skin barrier and increases the rate of absorption into the bloodstream, leading to greater systemic exposure.
The risk of accidental ingestion is high, particularly when treating children. Borax is rapidly absorbed through the gastrointestinal tract if swallowed, with over 90% entering the system. Acute poisoning can manifest with severe gastrointestinal symptoms, including persistent vomiting, nausea, abdominal pain, and diarrhea.
More severe systemic toxicity can lead to kidney damage and central nervous system effects, such as convulsions, lethargy, and headaches. Infants and small children are especially vulnerable due to their smaller body mass and higher surface area to volume ratio, which increases the relative amount of substance absorbed. Additionally, borax dust can cause respiratory irritation if inhaled, a risk when applying any powder-based substance to the hair.
Recommended and Safe Treatment Options
Since borax is neither effective nor safe, individuals should use medically reviewed and approved treatments. Approved treatments fall into two main categories: over-the-counter (OTC) and prescription medications. Health bodies recommend starting with OTC products, known as pediculicides.
OTC options commonly include products containing permethrin or pyrethrins, which are neurotoxic to the lice, paralyzing and killing them. Permethrin is a synthetic compound similar to pyrethrins. While resistance has been observed, these products remain a frontline defense. A second application is often required seven to nine days after the first to kill any lice that hatch from surviving nits.
For persistent infestations or when OTC treatments fail, a healthcare provider may prescribe stronger medications. Prescription options include:
- Benzyl alcohol lotion, which works by suffocating the lice.
- Malathion lotion, an organophosphate that kills both lice and some eggs.
- Spinosad topical suspension.
- Ivermectin lotion.
Both spinosad and ivermectin are effective and approved for use in young children.
Regardless of the chemical treatment chosen, mechanical removal remains a practical and complementary strategy. Using a fine-toothed nit comb on wet hair is highly effective at physically removing lice and nits from the hair shaft. Combining a medically approved product with careful, repetitive combing is the most reliable method for successful eradication.