Permethrin: What It Is, How It Works, and What It Treats

When you hear permethrin, a synthetic chemical used to kill mites and lice on the skin and clothing. Also known as a topical insecticide, it’s one of the most trusted treatments for scabies and head lice — especially when other options fail. Unlike oral meds, permethrin works right where it’s applied. No need to swallow it. No system-wide side effects. Just direct action on the pests hiding in your skin or hair.

It’s not just for people. Permethrin is also used on clothing, bed linens, and even mosquito nets to repel or kill insects. That’s why travelers and outdoor workers often carry permethrin-treated gear. The chemical sticks to fabric and stays active for weeks. For scabies, you rub it on your whole body from the neck down, leave it on for 8–14 hours, then wash it off. For lice, you apply it to dry hair, wait 10 minutes, then rinse. Simple. No magic. Just science.

But permethrin isn’t a cure-all. It doesn’t work on fleas, ticks, or bed bugs the same way. And it won’t kill eggs unless you repeat the treatment. That’s why some people need a second round. Also, it’s not for babies under 2 months. Pregnant women should check with a doctor first. Some folks report mild burning or itching after use — usually temporary. But if your skin gets red, swollen, or blistered, stop using it. That’s not normal.

People often mix up permethrin with pyrethrin, which comes from chrysanthemum flowers. Permethrin is man-made, stronger, and lasts longer. That’s why it’s in most over-the-counter lice shampoos and prescription scabies creams. It’s also the go-to for public health programs in places where scabies spreads fast — schools, nursing homes, shelters.

You’ll find permethrin in creams, lotions, sprays, and even impregnated fabrics. But not all products are equal. The concentration matters. A 5% cream is for scabies. A 1% lotion is for lice. Using the wrong one won’t help — and could irritate your skin. Always read the label. Don’t guess.

There’s also a growing concern about resistance. In some areas, lice are starting to shrug off permethrin. That’s why doctors now sometimes recommend alternatives like ivermectin or malathion. But for most people, permethrin still works. Fast. Cheap. Effective.

And yes, it’s safe when used right. But keep it away from eyes, mouth, and open wounds. Wash your hands after applying. Don’t use it on pets unless it’s labeled for animals — dog permethrin can kill cats. That’s a real danger.

What you’ll find below are real stories and practical guides from people who’ve used permethrin — and lived to tell about it. From how to spot scabies before it spreads, to what to do when the itching won’t quit, to how to clean your house so it doesn’t come back. No fluff. No theory. Just what works.