Getting rid of lice takes a combination of killing live lice, removing their eggs, and cleaning your immediate environment to prevent reinfestation. Most cases clear up within one to two weeks with the right approach. Here’s a step-by-step breakdown of what actually works.
Confirm It’s Actually Lice
Before you treat anything, make sure you’re dealing with an active infestation. Lice are dark-colored and about the size of a poppy seed. You’ll spot them crawling on the scalp, especially where the hair parts. Their eggs (called nits) are white or yellowish-brown and attach to the hair shaft about a quarter inch from the scalp.
The simplest way to tell nits apart from dandruff: try to flick or pull the speck off the hair. Dandruff slides off easily. Nits don’t. They’re glued to the shaft and resist removal. If you’re only finding nits more than a quarter inch from the scalp with no live lice, you may be looking at an old, already-resolved infestation rather than an active one.
Over-the-Counter Treatments
The most common first step is an OTC lice-killing product containing permethrin or pyrethrins. These are available at any pharmacy without a prescription. You apply the product to damp hair, leave it on for the time specified on the label, then rinse. One important detail: don’t use conditioner or a combination shampoo/conditioner before applying treatment. Conditioner coats the hair and can prevent the active ingredient from reaching the lice.
Here’s the catch. Most OTC products kill live lice but do not kill all the eggs. That means a second treatment 7 to 9 days later is usually necessary to catch any lice that hatched after the first round. Skip that second treatment, and you risk the whole cycle starting over.
When OTC Products Don’t Work
If you’ve followed the directions carefully, done the second treatment, and still see live lice crawling, the lice may be resistant to the active ingredients in standard OTC products. Resistance to permethrin-based treatments has become increasingly common in many parts of the United States. At that point, a prescription treatment is the next step.
Several prescription options work through different mechanisms, which means resistant lice are still vulnerable to them:
- Benzyl alcohol lotion (5%): Kills live lice by suffocating them rather than using a traditional insecticide. Does not kill eggs, so a second treatment is needed.
- Ivermectin lotion (0.5%): Approved for ages six months and older. It kills live lice and, while it doesn’t destroy eggs directly, prevents newly hatched lice from surviving. Often effective with a single application.
- Malathion lotion (0.5%): Kills live lice and some eggs.
- Spinosad suspension (0.9%): Derived from soil bacteria. This one kills both live lice and unhatched eggs, so retreatment is usually not needed.
Wet Combing: The Chemical-Free Option
If you want to avoid chemicals entirely, or if you’re treating a very young child, wet combing is a legitimate standalone method with solid clinical evidence behind it. It takes more time and patience, but it works.
Here’s the process:
- Wash the hair with ordinary shampoo.
- Apply a generous amount of conditioner to make the hair slippery.
- Use a wide-toothed comb first to detangle.
- Switch to a fine-toothed lice comb (metal ones work best). Slot the teeth into the hair at the roots, with the comb lightly touching the scalp, and draw it all the way down to the ends.
- After every single stroke, check the comb and wipe or rinse off any lice you find.
- Work through the entire head section by section.
- Rinse out the conditioner.
The key to making wet combing work is repetition. You need to repeat the full process every 3 days until you’ve had four consecutive sessions with no lice found. That typically takes about two weeks. Miss a session, and you give newly hatched lice time to mature and lay new eggs.
What About Home Remedies?
Mayonnaise, olive oil, coconut oil, and petroleum jelly are all popular “suffocation” remedies that circulate online. The idea is that coating the hair in something thick will smother the lice. There’s limited clinical evidence that this approach reliably works, and none of these methods kill eggs effectively.
Tea tree oil gets a lot of attention, but the research is underwhelming. In a 2011 randomized trial, tea tree oil killed about 45% of lice eggs in lab conditions, compared to 70% for a standard suffocation-type product. Better than nothing, but not a reliable standalone treatment. A 2012 study found better results when tea tree oil was combined with another plant compound called nerolidol, though that was also a lab study, not a real-world test on people’s heads. If you want to try tea tree oil, treat it as a supplement to proven methods, not a replacement.
Cleaning Your Home
Lice cannot survive long without a human host, but they don’t die instantly either. At room temperature (about 74°F), adult lice live 2 to 4 days off a person’s head. Nits can remain alive off the host for up to 10 days. That’s why some household cleanup matters, though you don’t need to fumigate the house or throw anything away.
Focus on items the infested person used in the two days before treatment:
- Machine wash clothing, bedding, and towels in hot water (130°F) and dry on high heat for at least 20 minutes. Temperatures above 125°F for 10 minutes are lethal to both lice and eggs.
- Soak combs and brushes in hot water (at least 130°F) for 5 to 10 minutes.
- Items that can’t be washed, like stuffed animals or decorative pillows, can go in a sealed plastic bag for two weeks. Any lice or nits inside will die.
- Vacuum floors and furniture where the infested person sat or lay. That’s sufficient. You do not need to spray insecticide on furniture or carpets.
Why Treatment Sometimes Fails
The CDC identifies five common reasons lice treatment doesn’t work: misdiagnosis (it wasn’t lice to begin with), using conditioner before treatment, not following the product instructions closely, lice resistance to the medication, and reinfestation from an untreated contact. That last one is a big one that people overlook.
Check everyone in the household and anyone who shares a bed with the infested person. Treat all infested individuals at the same time. If you treat your child on Monday but their sibling isn’t checked until Friday, those five days are enough for lice to move back and forth. The same goes for close friends or classmates who’ve had head-to-head contact. Lice spread almost exclusively through direct hair-to-hair contact, not by jumping or flying (they can’t do either).
After treatment, continue checking for live lice every few days for two to three weeks. Finding a few nits that are firmly attached close to the scalp doesn’t necessarily mean treatment failed, but spotting live, crawling lice does. If that happens, switch to a different treatment method rather than repeating the same one that didn’t work.