What does not work against lice? - briefly
Products without a genuine insecticide—such as standard shampoos, petroleum‑based oils, «vinegar», «mayonnaise» or simple washing—do not eradicate head lice.
What does not work against lice? - in detail
Ineffective approaches to lice control fall into several categories.
Commonly marketed over‑the‑counter products that claim immediate eradication often lack active ingredients proven to kill lice. Products containing only petroleum‑based substances, such as petroleum jelly or baby oil, coat the insects without penetrating their exoskeleton, leaving the infestation unchanged. Alcohol‑based sprays may temporarily immobilise adult lice but do not affect eggs, resulting in rapid reinfestation.
Home‑remedy treatments frequently suggested in popular media also lack scientific support. Rinses made from vinegar, lemon juice, or diluted essential oils do not achieve lethal concentrations for lice or nits. Applying mayonnaise, olive oil, or similar thick substances creates a barrier that hinders combing but does not kill the parasites. Heat‑based methods, including hair dryers set to high temperature or placing the head under a hot lamp, fail because the required temperature to exterminate lice (above 46 °C) cannot be sustained safely on the scalp.
Mechanical removal techniques can be ineffective when applied incorrectly. Using a fine‑toothed lice comb without prior wetting of the hair, or combing only a short segment before discarding the tool, leaves many lice and nits intact. Repeated combing without systematic sectioning and thorough inspection does not guarantee complete elimination.
Insecticidal products designed for other pests, such as ant or roach sprays, do not contain the specific neurotoxic agents required to affect lice physiology and therefore provide no benefit.
Prescription medications may lose efficacy due to resistance development. Permethrin‑based creams, once highly effective, now encounter strains of Pediculus humanus capitis with reduced susceptibility, rendering standard regimens insufficient.
Summary of measures that do not eliminate lice:
- Petroleum jelly, baby oil, and similar occlusive agents
- Alcohol sprays or wipes applied without nit‑targeted action
- Vinegar, lemon juice, and unverified essential‑oil mixtures
- Mayonnaise, olive oil, and other thick food‑grade substances
- Hair‑dryer heat, hot‑lamp exposure, or other non‑controlled heat sources
- Standard shampooing with regular or medicated shampoo alone
- Insecticidal sprays intended for ants, roaches, or flies
- Improper combing techniques lacking thorough sectioning and repeated passes
- Treatments relying on outdated permethrin formulations in regions with documented resistance
Effective lice eradication requires agents proven to kill both adult insects and their eggs, applied according to validated protocols. Any method listed above should be regarded as insufficient for definitive control.