Head Lice: How to Spot, Treat & Prevent Them (Even Resistant Lice)

How Lice Spread & How to Spot Them

Lice move by crawling head to head—classrooms, sports huddles, and family cuddles are the transmission hotspots. They are equal-opportunity residents: clean, dirty, long, short, curly, straight hair all host them, and animals are not involved. Off the scalp they die within a day, so bedding and hats play a small role compared to direct contact.

Adult lice run about the size of a sesame seed and are gray-brown; eggs (nits) are pinhead-white, firmly glued to hair shafts near the scalp—classically behind the ears and at the nape. Other clues: an itchy scalp, a fine rash at the neckline, and the unsettling feeling of movement. Because itching can take weeks to develop after first infestation, a wet-comb check catches cases earlier than symptoms do.

Treatment That Works in 2025

The classic first line—a permethrin 1% cream rinse—has lost much of its authority: laboratory surveys have found survival rates above 90% in sampled lice populations. Modern strategy blends methods. Wet combing: coat conditioned hair in sections with a fine detection comb every 3–4 days for two weeks, clearing hatching lice before they mature. Chemicals: oral ivermectin (single dose, repeated at day 7–10), spinosad or benzyl alcohol lotion, and malathion for resistant cases, all under clinician or pharmacist guidance.

• Treat only confirmed live lice—empty nits alone do not justify chemicals.
• Check and treat all household members on the same day; leave pets out of it.
• Comb from scalp to tip, wiping the comb on white paper after each stroke.
• Wash worn headwear and pillowcases in hot water and dry on high; seal other items in a bag for 48 hours.
• Return to school or work after the first effective treatment—'nit-free' exclusion policies are outdated.