Permethrin cream is a topical medication used to treat two parasitic skin infestations: scabies and head lice. It comes in two concentrations, each designed for a different problem. The 5% cream treats scabies, while the 1% lotion treats head lice. Both work by disrupting the nervous system of the parasites, causing paralysis and death at all life stages.
Scabies: The Primary Use
The 5% permethrin cream is the standard first-line treatment for scabies, an intensely itchy skin condition caused by microscopic mites that burrow into the top layer of your skin. These mites lay eggs in tiny tunnels beneath the surface, which is why the cream needs to cover your entire body rather than just the areas that itch.
To treat scabies, you apply a thin layer of cream to all skin from the neck down to the soles of your feet. Every fold and crease matters: between your fingers and toes, around your waist, behind your ears, and along your buttocks. You may need the entire tube to cover your body adequately. For infants (at least 2 months old) and adults over 65, the cream should also go on the scalp, hairline, temples, and forehead. Keep the cream away from your eyebrows and eyelashes.
Leave the cream on for 8 to 14 hours, then wash it off in the shower. Most people apply it before bed and rinse it off the next morning. A second application is typically recommended about one to two weeks later to catch any mites that may have hatched from eggs since the first treatment.
Head Lice Treatment
The 1% permethrin lotion treats head lice infestations. For this use, you shampoo your hair with regular shampoo first, then apply the permethrin lotion to damp hair and scalp. The process is simpler than scabies treatment since it targets only the head rather than the whole body.
How Permethrin Kills Parasites
Permethrin targets voltage-gated sodium channels in the nerve cells of mites and lice. Normally, these channels open briefly to send electrical signals through the parasite’s nervous system, then snap shut. Permethrin forces them to stay open far longer than they should, flooding the nerve cells with sodium ions. This creates uncontrollable hyperexcitability in the nerves, which leads to paralysis and death. The mechanism works on parasites at every stage of development, from eggs to adults.
Importantly, permethrin is far more toxic to insects and mites than to humans. Very little of it absorbs through the skin, which is why it can sit on your body for hours without causing systemic effects.
Side Effects and Post-Treatment Itching
The most common side effects are mild and localized: burning or stinging at the application site, slight redness, and skin dryness. These typically resolve on their own.
One thing that catches people off guard is that itching and rash can persist for two to four weeks after successful treatment. This doesn’t mean the treatment failed. Your immune system is still reacting to the dead mites, their eggs, and their waste products left behind in the skin. The body needs time to clear that debris. If itching is getting worse rather than better after a few weeks, that’s a different situation worth discussing with your provider.
Allergic reactions are rare but possible. Signs include hives, swelling of the face, lips, or throat, and widespread skin rash beyond what you’d expect from the treated condition itself.
Why Cleaning Your Environment Matters
Permethrin cream treats your skin, but mites can survive briefly on clothing, bedding, and soft surfaces. Without proper environmental cleaning, you can re-infest yourself right after treatment. The good news: scabies mites can only survive about three days without a human host, so you don’t need to fumigate your house. You just need to cut off their path back to your skin.
Wash all clothing, towels, and bedding used in the past three days at 60°C (140°F) on a full wash cycle, not a quick one. Items that can’t be washed at that temperature go into a sealed plastic bag and get set aside for at least three days. This includes items people often forget:
- Bathrobes and slippers
- Scarves, gloves, and earmuffs (in winter)
- Phone and laptop cases made of fabric
- Cloth shoes
- Children’s stuffed animals
Vacuum anything made of fabric that can’t go in the washing machine or a sealed bag: sofas, upholstered chairs, carpets, rugs, and even car seats if you’ve sat on them with bare skin. Skip the steam cleaner. If you have a pet with a thick coat, minimize contact and keep them off furniture until three days after treatment. Mites won’t establish an infestation on animals, but fur can temporarily harbor them.
Treatment Failure and Rising Resistance
Permethrin works well for most people, but it doesn’t work for everyone. A large meta-analysis published in the British Journal of Dermatology found that permethrin had a treatment failure rate of about 10.8%, lower than the overall failure rate across all scabies treatments (15.2%). However, the data showed a troubling trend: failure rates have been climbing by roughly 0.58% per year over the past several decades.
The reasons behind rising failure rates aren’t fully understood. True drug resistance in scabies mites has never been formally assessed in clinical studies, so researchers can’t say definitively whether mites are becoming genetically resistant or whether other factors, like incomplete application or skipped environmental cleaning, are driving the numbers up. Interestingly, whether patients received one application or two didn’t make a statistically significant difference in failure rates, suggesting that re-treatment alone may not solve the problem when initial treatment doesn’t work.
If your symptoms are clearly worsening (not just lingering) after completing treatment, your provider may consider alternative medications or investigate whether the diagnosis was correct in the first place.
Safety for Children and During Pregnancy
Permethrin cream should not be used on infants younger than 2 months without a doctor’s guidance. For babies and toddlers who are old enough for treatment, the application area expands to include the scalp and face (avoiding the eyes), since young children are more likely to have mites in those areas.
If you’re pregnant or breastfeeding, the decision to use permethrin involves weighing the benefits of treating an active infestation against potential risks to the baby. This is a conversation to have with your provider, though permethrin is generally considered one of the safer options available for treating scabies during pregnancy because so little is absorbed through the skin.