Removing lice takes a combination of killing live lice, eliminating their eggs, and repeating the process to catch newly hatched nymphs before they can reproduce. Most infestations clear up within two weeks with consistent treatment. The key is understanding the lice life cycle and timing your efforts around it, because no single treatment kills every louse and every egg in one pass.
Confirm It’s Actually Lice
Before you start treatment, make sure you’re dealing with lice and not dandruff. The easiest test: try to flick the white speck off the hair strand. Dandruff slides right off or falls onto your shoulders when you shake your head. Lice eggs (called nits) are glued to the hair shaft and won’t budge without deliberate effort. You’ll find nits within a few millimeters of the scalp, because the eggs need warmth and proximity to a blood supply to survive. Dandruff flakes can appear anywhere on the head or hair.
Nits are tiny, oval-shaped, and clear to yellowish-white. Adult lice are about the size of a sesame seed, grayish-white, and move quickly through dry hair. If you’re having trouble spotting them, wet the hair and apply conditioner first. Moisture temporarily immobilizes lice, making them much easier to find.
Why Timing Matters: The Lice Life Cycle
Lice eggs hatch in 7 to 12 days. Once hatched, a nymph becomes a reproducing adult in about seven more days. That means you have roughly a one-week window after hatching to kill new lice before they start laying eggs of their own. This is why every effective treatment plan involves at least two rounds: the first kills live lice, and the second catches nymphs that hatched from surviving eggs.
Over-the-Counter Treatments
The two most common drugstore options are permethrin-based products and pyrethrin-based products. Pyrethrins are derived from chrysanthemum flowers and work by attacking the lice’s nervous system while being extremely low in toxicity to humans. Permethrin is a synthetic version that works similarly but also leaves a residue on the hair designed to kill nymphs as they hatch from eggs that survived the first treatment. Both are widely available as shampoos or cream rinses.
Here’s the problem: lice have developed significant resistance to these products. A large meta-analysis of global studies found that resistance to permethrin and related chemicals was about 33% before 2004, jumped to 68% between 2005 and 2015, and reached 82% after 2015. In the United States specifically, one study found that 98.3% of lice sampled carried a gene for resistance to these treatments. So if you use a standard drugstore product and it doesn’t seem to work after the full two-treatment cycle, resistance is the most likely explanation, not user error.
How to Apply OTC Treatments
Follow the product directions carefully, but the general process is straightforward. Apply the product to the hair (some require wet hair, others dry), leave it on for the specified time, then rinse. Most products recommend a second application 7 to 9 days later to kill any nymphs that hatched after the first treatment. Do not skip the second treatment, even if you don’t see any live lice. Eggs you can’t see may still be incubating.
Prescription Options
If over-the-counter treatments fail, prescription options work through different mechanisms that resistant lice haven’t adapted to. Spinosad is applied to dry hair and is approved for anyone six months and older. Ivermectin lotion is also applied to dry hair, left on for 10 minutes, then rinsed. Both are single-application treatments, which makes them simpler to use than OTC products that require a second round. Your doctor or pharmacist can help you choose based on age and preference.
Wet Combing: The Non-Chemical Approach
Wet combing is the most effective drug-free method and also works well alongside chemical treatments. You’ll need a fine-toothed lice comb (metal ones with closely spaced teeth work best), regular shampoo, and a generous amount of hair conditioner.
Start by shampooing and rinsing the hair. Then apply a thick layer of conditioner. The shampoo carries moisture to the hair roots where lice live, and the conditioner immobilizes them so they can’t scurry away from the comb. Section the hair and comb through each section from root to tip, wiping the comb on a paper towel after every pass to check for lice and nits.
The proven schedule for wet combing is sessions on days 1, 5, 9, and 13. Here’s the logic: each session removes all the hatched lice currently on the head, but it leaves behind eggs that haven’t hatched yet. Since eggs take a maximum of 10 days to hatch, any louse that hatches as late as day 10 will be caught and removed during the day 13 session, before it can mature and reproduce. If you skip a session or stop early, you risk letting a nymph reach adulthood and restart the cycle.
Dealing With Resistant “Super Lice”
If you’ve completed a full course of OTC treatment (both applications, properly timed) and still find live lice crawling on the scalp, you’re likely dealing with resistant lice. At this point, your best options are:
- Switch to a prescription treatment that uses a different mechanism than pyrethrins or permethrin
- Commit to the wet combing schedule as your primary method, since combing physically removes lice regardless of drug resistance
- Combine both approaches for the most thorough results
Do not simply repeat the same OTC product a third or fourth time. If the lice are genetically resistant, additional applications won’t change the outcome.
What About Home Remedies?
Olive oil, mayonnaise, coconut oil, and petroleum jelly are often suggested as suffocation treatments. The idea is that coating the hair in a thick, oily substance will block the lice’s ability to breathe. In practice, there’s limited clinical evidence that plain olive oil or mayonnaise reliably kills lice. Lice can survive for hours with their breathing pores closed, and getting thick substances fully removed from the hair afterward is its own challenge.
One study did find that a specially processed (ozonated) olive oil lotion cured all patients after one week of treatment, outperforming permethrin. But ozonated olive oil has dramatically different chemical properties than the bottle in your kitchen. The ozonation process increased its acidity 60-fold and its peroxide content 200-fold. Regular olive oil from the pantry is not a substitute.
If you want to try an oil-based approach, it’s most useful as a way to slow lice down for combing rather than as a standalone kill method. Apply the oil, comb thoroughly with a lice comb, and follow the four-session wet combing schedule.
Cleaning Your Home
The good news is that lice are not hardy survivors off the human head. Adult lice die within two days without a blood meal. Nits that fall off the scalp can’t hatch and typically die within a week without body heat to keep them warm. This means you don’t need to deep-clean or fumigate your entire house.
Focus on items that had direct contact with the infested person’s head in the past two days. Wash pillowcases, sheets, hats, scarves, and recently worn clothes in water that’s at least 50°C (122°F), or run them through a dryer cycle. Research on machine laundering found that either a water temperature of 50°C or higher, or a standard dryer cycle, is sufficient to kill both lice and their eggs. Items that can’t be washed (stuffed animals, decorative pillows) can be sealed in a plastic bag for two weeks to ensure any lice or nits die off naturally.
Vacuum upholstered furniture and car seats the infested person used recently. Skip the lice sprays for furniture. They contain pesticides you don’t need in your living space, and lice on surfaces are already dying without a host.
Preventing Reinfestation
Lice spread almost exclusively through direct head-to-head contact. They can’t jump or fly. Sharing combs, brushes, hats, or hair accessories carries some risk, but far less than people assume, because lice off the scalp are already weakened and dying.
Check all household members if one person is infested. Lice often spread through a family before anyone notices symptoms, since itching can take weeks to develop in a first-time infestation. Treat everyone who has live lice at the same time to prevent passing them back and forth. People without live lice or nits don’t need treatment.