Lice eggs (nits) are harder to eliminate than live lice because they’re encased in a protective shell and cemented to the hair shaft with a protein-based glue. Most over-the-counter lice treatments kill adult lice but leave eggs intact, which is why infestations come back. Getting rid of nits requires either a treatment that kills eggs directly, a method that physically removes them, or a combination of both.
Why Lice Eggs Are So Hard to Kill
A lice egg is essentially a tiny armored capsule. The shell protects the developing louse from chemicals that would kill an adult on contact, and the glue anchoring it to the hair is strong enough to survive normal washing and brushing. Nits hatch in about 6 to 9 days, so any treatment that misses the eggs risks a new round of lice within a week or two.
Most common lice products work by attacking the nervous system or breathing of live lice. Permethrin, the active ingredient in many drugstore treatments, paralyzes adult lice but has limited ability to penetrate the egg shell. Ivermectin-based treatments are also not ovicidal, meaning they don’t kill the egg itself. This is why product labels so often instruct you to repeat treatment 7 to 10 days later: they’re banking on catching newly hatched lice before they can lay more eggs.
Treatments That Actually Kill Eggs
A few treatments do have meaningful ovicidal activity. Malathion-based prescription lotions have been shown in multiple studies to kill both live lice and their eggs, making them more effective in a single round than permethrin. The trade-off is that malathion is a stronger chemical, has an unpleasant smell, and is flammable while wet, so it’s typically reserved for cases where milder options have failed.
Topical ivermectin lotion takes an interesting indirect approach. While it doesn’t destroy the egg itself, it paralyzes the mouth muscles of the louse that hatches from the egg, preventing it from feeding. The newly hatched louse dies before it can survive. In clinical trials, about 74% of treated participants were completely lice-free at day 15 after just a single application, compared to roughly 18% in a control group. The convenience of a one-time treatment makes it a practical option, especially for children who resist sitting through repeated sessions.
Heated Air Devices
Controlled heated air is one of the most effective ways to kill lice eggs without any chemicals. A professional device (originally called the LouseBuster, now marketed as AirAllé) blows carefully regulated warm air along the hair shaft and scalp. In research testing multiple hot-air methods, all achieved at least 88% egg mortality, and the purpose-built device reached nearly 100% egg kill. It was actually more effective against eggs than against hatched lice, which is the opposite of most chemical treatments.
These devices are only available at professional lice treatment centers, not for home use, and a session typically costs $100 to $200. But for families dealing with a stubborn or recurring infestation, one visit can end the cycle. A regular home hair dryer does not produce the same results because it doesn’t deliver enough sustained, evenly distributed heat, and using one at high settings risks scalp burns.
Physical Removal With a Nit Comb
Regardless of which treatment you choose, combing out nits with a fine-toothed metal nit comb is the most reliable way to physically remove eggs from hair. The teeth of a proper nit comb are spaced closely enough to catch the tiny eggs as the comb slides down the hair shaft. Plastic combs included with some treatment kits are often too flexible and too widely spaced to do the job well. Look for a rigid metal comb with long, closely spaced teeth.
To comb effectively, work on wet hair with a lubricant, whether that’s regular conditioner, the treatment product itself, or a detangling spray. Section the hair into small segments using clips and comb each section from root to tip, wiping the comb on a white paper towel after every pass so you can see what you’re pulling out. Viable nits look tan or brownish and are found close to the scalp, usually within a quarter inch. White or clear shells farther down the hair shaft are already hatched and empty.
Plan on spending 30 to 60 minutes per session depending on hair length and thickness. Repeat combing every 2 to 3 days for at least two weeks to catch any nits you missed and any that may have hatched between sessions. This timeline covers the full hatching window and then some.
Dimethicone (Silicone-Based Products)
Dimethicone is a silicone oil that coats lice and suffocates them by blocking their ability to regulate water. Because it works physically rather than chemically, lice can’t develop resistance to it the way they have to permethrin and other pesticides. It also makes hair slippery, which loosens the glue holding nits to the hair shaft and makes combing significantly easier.
In a clinical study of 100% dimethicone lotion, about 55% of participants were free of viable eggs after just one day. By day 14, that number climbed to nearly 81%, suggesting that the coating either killed or dislodged most eggs over time. The combination of the product’s viscosity and a fine comb was credited with much of the egg removal success. Dimethicone products are available over the counter in many countries and are well tolerated, even in young children.
What Doesn’t Work on Eggs
Vinegar is the most popular home remedy for loosening nits, based on the idea that acetic acid dissolves the glue attaching eggs to the hair. In practice, studies have found vinegar ineffective against lice eggs. It doesn’t dissolve the glue at the concentrations found in household vinegar, and it doesn’t kill the developing louse inside. Soaking hair in vinegar before combing might make the hair easier to work through, but it won’t do anything a regular conditioner wouldn’t do just as well.
Olive oil, mayonnaise, and petroleum jelly are sometimes recommended as suffocation methods. While they may slow down or kill some adult lice if left on long enough (typically 8 or more hours under a shower cap), they don’t penetrate the egg shell. You’ll still need to comb out every nit manually, and the greasy residue can take several washes to remove. Essential oils like tea tree oil lack consistent evidence of ovicidal activity and can irritate the scalp, especially in children.
Cleaning Your Environment
Lice eggs need the warmth of the human scalp to survive and hatch. Nits that fall off the head onto a pillow or hat are unlikely to hatch at room temperature, and a louse that did hatch away from the scalp would die within hours without a blood meal. That said, basic precautions reduce the small risk of reinfestation.
Wash pillowcases, sheets, hats, and any fabric that touched the head in the past two days using hot water (at least 130°F or 54°C) and dry on high heat for at least 20 minutes. Items that can’t be washed, like stuffed animals or decorative pillows, can be sealed in a plastic bag for two weeks. This exceeds the hatching window and ensures anything alive inside has died. Vacuuming furniture and car seats is reasonable but not critical. Lice don’t live in carpets or jump from surfaces, so there’s no need to deep-clean your entire house.
Putting It All Together
The most effective approach combines a treatment with real ovicidal activity (or one that prevents hatched lice from surviving) with thorough, repeated nit combing. A realistic plan looks like this: apply your chosen treatment on day one, then comb out nits on wet, lubricated hair every two to three days for two full weeks. Check again at the three-week mark to confirm no new lice have appeared. If you’re still finding live lice after a complete round of treatment and combing, the lice may be resistant to the product you used, and switching to a different mechanism of action (for example, from a pesticide to dimethicone or a heated-air treatment) is the logical next step.