Nix Lice Killing Creme Rinse is a single-application treatment you leave on damp hair for 10 minutes, then rinse out. The active ingredient kills live lice on contact, but getting the full effect depends on how you prep the hair beforehand, how thoroughly you apply it, and whether you follow up with proper combing in the days after. Here’s exactly how to do each step.
Prep Your Hair the Right Way
What you put on your hair before Nix matters more than most people realize. Wash with a plain shampoo that does not contain conditioner. No 2-in-1 shampoos, no standalone conditioners. Conditioner leaves a coating on the hair shaft that interferes with how the treatment binds to the hair, and the CDC lists it as one of the top reasons lice treatment fails.
After shampooing, rinse thoroughly with water and towel dry so the hair is damp but not dripping wet. You want enough moisture for the product to spread easily, but not so much water that it dilutes the treatment.
How to Apply Nix Step by Step
Shake the bottle well before opening it. Then apply the creme rinse in this order:
- Start behind the ears and at the nape of the neck. These are the warmest spots on the scalp and where lice tend to concentrate. Getting product here first ensures the heaviest populations get treated immediately.
- Work outward until hair and scalp are completely saturated. Don’t skim on coverage. Every strand from root to tip needs to be coated. For thick or long hair, you may need the entire bottle.
- Protect the eyes. Hold a washcloth or towel against the forehead to keep the product from dripping down. If it does get into the eyes, flush immediately with water.
Leave Nix on for exactly 10 minutes. No longer. Set a timer. When the time is up, rinse thoroughly with warm water, then towel dry and gently comb out any tangles.
Using the Nit Comb After Treatment
Nix kills live lice, but it won’t remove the eggs (nits) glued to individual hair strands. Those need to come out manually with the fine-toothed comb included in the box. This step is not optional if you want to avoid a reinfestation.
Separate the hair into small sections, roughly the width of the comb. Starting at the scalp, pull the comb slowly all the way to the tip of the hair. Comb each section several times before clipping it back and moving to the next one. Keep a spray bottle handy to re-dampen sections as you work. After each pass, wipe the comb on a paper towel or rinse it in a bowl of water to remove any nits or debris you’ve collected.
For short hair that’s hard to section, comb all the hair to the right, then to the left, then from back to front. Repeat this pattern several times.
The combing doesn’t end on day one. Plan to inspect and comb through the hair every other day for two full weeks. This catches any nits you missed the first time and any new eggs that may have been laid before the remaining lice died.
When to Apply a Second Treatment
Check the hair seven days after the first application. If you see any live, crawling lice at that point, apply a second treatment using the same steps: plain shampoo, towel dry, saturate, wait 10 minutes, rinse. The seven-day window matters because lice eggs hatch in roughly that timeframe. A second treatment catches any newly hatched lice before they’re old enough to lay eggs of their own.
If you don’t see any live lice at the seven-day check, you likely don’t need a second application. Continue combing every other day through the two-week mark to be sure.
Cleaning Your Home After Treatment
Lice can survive briefly on fabric and furniture, so treating the hair alone isn’t enough. On the same day you apply Nix, wash all bedding, towels, and recently worn clothing in hot water. Research on laundering and lice found that water needs to reach at least 50°C (about 122°F) to reliably kill both lice and their eggs. Most home washing machines set to a “hot” cycle meet or exceed that temperature. Running items through a dryer on high heat also works.
For items you can’t wash, like stuffed animals, decorative pillows, or headphones, seal them in a plastic bag for two weeks. Lice can’t survive more than a day or two without a human host, so this waiting period starves out anything living on the item. Vacuum upholstered furniture, car seats, and carpet where the infested person has been sitting or lying down.
Who Can Use Nix Safely
Nix Creme Rinse (1% permethrin) is approved for adults and children ages 2 and older. For children under 2, a doctor needs to determine whether it’s appropriate and at what dose. If you have a ragweed allergy or sensitivity to chrysanthemums, mention this before using the product, since permethrin is derived from a related plant compound. Anyone with severe scalp inflammation, such as open sores or an active skin condition, should also check with a healthcare provider first, as the product can worsen irritation on broken skin.
What to Do If Nix Doesn’t Work
Permethrin resistance in lice has been growing for years. The product still works in many cases, but populations of lice in some regions carry genetic mutations that make them less susceptible to permethrin. If you’ve followed every step correctly, used no conditioner, applied a second treatment at the seven-day mark, and still see live lice crawling, resistance is the likely explanation.
At that point, you’ll want to switch to a different type of treatment rather than repeating Nix a third time. Prescription options work through different mechanisms that resistant lice haven’t adapted to. Your doctor or pharmacist can recommend an alternative based on what’s available in your area. In the meantime, consistent nit combing every other day remains one of the most effective tools regardless of which product you use, since no louse can develop resistance to being physically removed.