Permethrin comes in three main forms, each with different concentrations and instructions: a 5% cream for scabies, a 1% lotion for head lice, and a 0.5% spray for treating clothing and gear against ticks and mosquitoes. How you use it depends entirely on what you’re treating. Here’s a clear walkthrough for each.
Using Permethrin 5% Cream for Scabies
The 5% cream is a prescription product designed to kill scabies mites burrowed into the skin. An average adult needs about 30 grams (one full tube) for a single application. If you’re a larger person or treating multiple household members, make sure you have enough before you start.
Apply the cream to every area of your body from the neck down. That means between your fingers, under your nails, on the soles of your feet, behind your ears, and in skin folds you might normally skip. Scabies mites favor warm, hidden areas, so thorough coverage matters more than a thick layer. For infants and young children, the scalp, hairline, and forehead are typically included as well.
Leave the cream on for 8 to 14 hours. Most people apply it before bed and wash it off in the morning, which makes the timing straightforward. Use lukewarm water to rinse. You can resume normal bathing afterward.
One important detail: itching often continues for one to two weeks after successful treatment. This is a reaction to the dead mites still in your skin, not a sign the treatment failed. If you see live mites 14 days or more after your first application, apply a second round using the same process.
Using Permethrin 1% Lotion for Head Lice
The 1% lotion is available over the counter for head lice. Start by washing your hair with regular shampoo (no conditioner) and towel-drying it so it’s damp but not dripping. Apply the lotion to cover all of the hair and scalp, paying extra attention behind the ears and at the nape of the neck where lice tend to cluster. Leave it on for 10 minutes, then rinse thoroughly with warm water.
After rinsing, comb through with a fine-toothed nit comb to remove dead lice and eggs. This step is tedious but significantly improves results, since the lotion kills live lice more reliably than it destroys eggs.
Check your hair again seven days later. If you still see live lice, repeat the full process. The second treatment targets any lice that hatched from surviving eggs after the first round.
Permethrin Resistance in Lice
Permethrin’s effectiveness against head lice has dropped significantly over the past few decades. In the 1980s, cure rates were close to 100%. Today, in some populations, they’ve fallen as low as 25%. The genetic mutation that makes lice resistant is found in roughly 97% of lice in the United States, which means permethrin may not work well depending on where you live. If you’ve tried permethrin twice without success, the lice are likely resistant, and you’ll need a different approach. Your pharmacist or doctor can recommend alternatives that work through different mechanisms.
Treating Clothing and Gear With Permethrin Spray
The 0.5% spray is designed for fabrics, not skin. It’s used to repel and kill ticks, mosquitoes, and other biting insects on clothing, shoes, tents, backpacks, and other outdoor gear. This is especially popular among hikers, hunters, and anyone spending time in tick-heavy areas.
Lay your clothing flat outdoors or in a well-ventilated area. Spray each side evenly until the fabric is damp but not soaked, then let it dry completely before wearing. Drying time varies by product, so check the label. Once dry, the treatment is bound to the fabric fibers and provides protection through multiple wash cycles. Again, the exact number of washes depends on the specific product, so the label is your guide.
You can also buy clothing that comes pre-treated with permethrin from several outdoor brands. These factory-treated items generally last longer than DIY spray applications.
Cleaning Your Home During Treatment
Whether you’re treating scabies or lice, the bugs can survive on bedding, towels, and recently worn clothes. On the same day you apply permethrin, wash all bedding, towels, and clothing you’ve used in the past few days in hot water and run them through a hot dryer. Temperatures above 122°F (50°C) sustained for 10 minutes kill both mites and their eggs.
Items that can’t be washed (stuffed animals, decorative pillows, dry-clean-only clothes) can be sealed in a plastic bag for several days. Scabies mites can’t survive more than two to three days without a human host, and lice die within a similar window. Vacuum upholstered furniture and carpets, then dispose of the vacuum bag.
Permethrin and Cats
Permethrin is highly toxic to cats. Their livers lack the enzyme pathway that dogs and humans use to break down the compound, so even small exposures can cause it to accumulate and affect the nervous system. The ASPCA’s Animal Poison Control Center lists permethrin as one of the most common causes of cat poisoning, and most cases happen when owners accidentally apply a dog flea product to a cat or when a cat grooms a recently treated dog.
If you have cats at home, take precautions. After applying permethrin cream to your skin, keep treated areas covered or avoid close contact with your cat until you’ve washed the cream off. If you’re spraying clothing, do it in a separate room and make sure the fabric is fully dry before your cat can access it. Store all permethrin products where cats can’t reach them, and never use permethrin-based flea treatments on cats, even in small amounts.
What to Expect After Application
Mild burning, stinging, or tingling at the application site is common and typically fades within a few hours. Some temporary redness or numbness in the skin is also normal. These reactions happen because permethrin interacts with nerve fibers in the skin before being broken down by your body.
For scabies, the post-treatment itch can be genuinely frustrating because it feels identical to the original infestation. Cool compresses and over-the-counter anti-itch creams can help bridge that one-to-two-week window while your skin calms down. The key marker is the 14-day check: if you’re still seeing live mites at that point, retreat. If not, the treatment worked and the itch will resolve on its own.
For lice, check at the seven-day mark. Finding a few dead lice or empty egg casings (nits) stuck to hair shafts is normal and doesn’t mean the treatment failed. You’re looking specifically for live, moving lice. If you find them, repeat the process.