How can lice on the head be poisoned? - briefly
Apply a pediculicide with permethrin, pyrethrin, or malathion, which interferes with the louse’s nervous system and causes swift mortality. For resistant cases, oral ivermectin can be prescribed to deliver systemic toxicity to the parasites.
How can lice on the head be poisoned? - in detail
Effective eradication of head‑lice infestations relies on substances that rapidly disrupt the insect’s nervous system, respiration, or cuticle integrity. The most common categories include neurotoxic insecticides, respiratory inhibitors, and physical agents that cause desiccation.
Neurotoxic compounds act on acetylcholine receptors or voltage‑gated sodium channels, causing uncontrolled nerve firing and paralysis. Examples:
- Permethrin (0.5 % cream rinse) – synthetic pyrethroid that prolongs sodium channel opening.
- Pyrethrins combined with piperonyl‑butoxide – natural pyrethrins enhanced by a synergist that blocks metabolic detoxification.
- Spinosad (0.9 % lotion) – derived from bacterial fermentation, interferes with nicotinic acetylcholine receptors.
Respiratory inhibitors impair the lice’s tracheal system, leading to asphyxiation. Common agents:
- Malathion (0.5 % lotion) – organophosphate that inhibits acetylcholinesterase, indirectly affecting respiration.
- Carbaryl (0.6 % shampoo) – carbamate that blocks cholinesterase activity, causing respiratory failure.
Desiccating agents damage the exoskeleton, causing rapid water loss:
- Dimethicone (silicone‑based oil) – coats the cuticle, blocks spiracles, and dehydrates the insect.
- Ivermectin (0.5 % lotion) – binds to glutamate‑gated chloride channels, leading to paralysis and eventual dehydration.
Application guidelines:
- Apply the product to dry hair, ensuring full coverage of the scalp and all strands.
- Leave the preparation on the scalp for the manufacturer‑specified duration (typically 10–15 minutes).
- Rinse thoroughly with warm water.
- Repeat treatment after 7–10 days to target newly hatched nymphs.
- Comb wet hair with a fine‑toothed nit comb to remove dead insects and eggs.
Safety considerations:
- Verify absence of skin lesions or allergic reactions before use.
- Avoid contact with eyes; rinse immediately if exposure occurs.
- Use protective gloves if handling concentrated formulations.
- Store products out of reach of children and pets.
Resistance management:
- Alternate between substances with different modes of action (e.g., pyrethroid followed by dimethicone) to reduce selection pressure.
- Monitor treatment efficacy; persistent infestation may indicate resistant lice, requiring prescription‑only options such as oral ivermectin.
Proper execution of these chemical strategies, combined with mechanical removal, provides a comprehensive approach to eliminating head‑lice populations.