Permethrin
Scabicides and pediculicides
Scabicides and pediculicides
A synthetic pyrethroid cream that paralyses the scabies mite. First-line topical treatment for scabies; also used for lice, where resistance is common.
Quick facts
- Group
- Scabicides and pediculicides
- Target
- Voltage-gated sodium channel in the nerve membrane of the mite or louse
- Used for
- Scabies · Head
- Key effects
- Mild · Itching · Rash
- Monitor
- Signs of secondary bacterial infection
- ATC
- P03AC04
No doses: the clinician sets them by the current guideline.
Mechanism of action
Permethrin is a synthetic pyrethroid, related to the natural pyrethrins. It acts on the nerve cell membrane of mites, lice and other arthropods and disturbs the sodium current that controls repolarisation: the channels stay open, repolarisation is delayed, and the parasite is paralysed and dies. Very little crosses human skin, and what is absorbed is quickly split by ester hydrolysis into inactive metabolites.
- Permethrin reaches the nerve membrane of the mite or louse
- Sodium channels stay open; repolarisation is delayed
- The parasite is paralysed and dies
- The little absorbed in people is hydrolysed to inactive metabolites
Indications
- Scabies (Sarcoptes scabiei), including in pregnancy and in infants from two months Scabies →
- Head, body and pubic lice (lotion), where local resistance allows Pediculosis (head, body and pubic lice) →
Adverse effects
Common
- Mild, transient burning or stinging after application
- Itching, redness, numbness or tingling of the skin
- Rash
- Temporary worsening of the itch and redness of scabies
Contraindications
- Hypersensitivity to permethrin, to any synthetic pyrethroid or pyrethrin, or to any component
Key interactions
- Hair conditioner or conditioning shampoo (head-lice lotion)
- Coats the hair and makes the lotion work less well; plain shampoo is used before treatment.
What is monitored
- Live mites 14 days after treatment mean a second application is needed
- Persistent itch alone is rarely treatment failure
- Signs of secondary bacterial infection (pus, crusts, impetigo)
- That all household members and close contacts were treated
Administration and safety
- Cream is massaged into all the skin from the neck to the soles, including skin folds, between fingers and toes and under the nails; in infants and older adults also the scalp, temples and forehead.
- It is left on overnight and then washed off by bathing; it is reapplied to the hands if they are washed during that time.
- Kept away from the eyes, mouth, nose and other mucous membranes; eyes are flushed with water if contaminated.
- Head-lice lotion is applied to towel-dried hair, left on briefly and rinsed over a sink, not in the shower.
Pregnancy and breastfeeding
Very little is absorbed, and it is considered a safe choice for scabies in pregnancy and breastfeeding.
Nursing care
- Check that every household member and close contact is treated on the same day, even without symptoms.
- Teach to wash clothing, towels and bedding hot, or seal unwashable items in a bag for several days.
- Explain that itch may continue for weeks and is not, alone, a reason to re-treat.
- Watch for crusted scabies in immunosuppressed patients: it is highly contagious, and their rooms need careful cleaning.
Pharmacokinetics
- Absorption
- Very little crosses the skin, even in heavy scabies.
- Metabolism
- Rapid ester hydrolysis to inactive metabolites.
- Elimination
- Mainly in urine.
- Onset and duration
- Kills mites during the application; itch can persist for weeks after cure.
Test yourself
Think of the answer, then tap the question to see it.
How does permethrin kill the scabies mite?
It disturbs the nerve sodium channels of the mite, delaying repolarisation, so the mite is paralysed and dies.
Which body areas are often missed when applying permethrin for scabies?
Between the fingers and toes, under the nails, skin folds, the waist and buttocks, and the soles; in infants and older adults also the scalp and face.
Why is permethrin less useful for head lice in many countries?
Resistance in lice (mutations in the sodium channel) has become common.
Connections
← Back to the class: Scabicides and pediculicides
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Permethrin Topical: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - PERMETHRIN cream (DailyMed (U.S. National Library of Medicine), 2026); Scabies: Diagnosis and Treatment with Images (DermNet, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.