Permethrin: Uses, Side Effects & Safety

What it is and what it's used for

Permethrin is a medicine applied to the skin that kills parasites living on or in the skin. It belongs to a group of medicines called pyrethroids, which are related to natural insect-killing substances found in chrysanthemum flowers. Its main use is the treatment of scabies, an intensely itchy skin condition caused by tiny mites that burrow into the skin. It is also used, in a weaker strength, to treat head lice.

In India, permethrin 5% cream is the usual treatment for scabies, while permethrin 1% lotion or shampoo is used for head lice. It is available from pharmacies, and the 5% cream for scabies is generally used on a doctor's or pharmacist's advice, because the diagnosis of scabies needs to be confirmed and close contacts usually need treatment too. Permethrin is not a general skin cream, not a moisturiser, and not a treatment for eczema, fungal infections, or ordinary itching — those conditions need a different diagnosis and treatment.

How it works (simple language)

Scabies mites are microscopic creatures that burrow into the top layer of the skin, where they lay eggs. The body's reaction to the mites and their waste causes the intense itching and rash of scabies. Permethrin is thought to work by attacking the nervous system of the mites and lice, paralysing and killing them, so that they can no longer burrow, feed, or lay eggs.

Because permethrin is applied to the skin, very little of it is normally absorbed into the rest of the body. Itching may not disappear immediately after treatment, even when the mites have been killed, because the skin takes time to heal and the body's allergic reaction to the dead mites settles slowly. This does not necessarily mean the treatment has failed, but if itching is still severe after a few weeks, a doctor should be asked to check again.

Dosage forms available in India (general info only)

In India, permethrin is most commonly available as a 5% cream in tubes for scabies, and as a 1% lotion or shampoo for head lice. Brands vary by pharmacy; well-known Indian examples include Permite cream and Perlice lotion, though availability and brand names change over time. The 5% cream and the 1% lotion are different strengths for different conditions and must not be swapped.

Never decide the dose yourself from this article. Always follow your doctor's prescription or the directions on the pack, and check with your pharmacist if you are unsure — especially for children, where the dose depends on the child's weight and age.

Side effects

Common: Mild itching, burning, stinging, tingling, numbness, or redness of the skin where permethrin is applied, and sometimes mild swelling or a temporary worsening of itching. These effects are usually mild and settle within a few days.

Serious — seek medical care: Seek care if the skin reaction becomes severe, with widespread blistering, swelling, or a rash that keeps spreading, or if you develop signs of a severe allergic reaction such as swelling of the face or lips, difficulty breathing, or a widespread rash. Seek urgent care if permethrin is accidentally swallowed, or if it gets into the eyes and causes ongoing pain, redness, or blurred vision. If scabies sores become painful, oozy, or crusty, or fever develops, this may mean a secondary skin infection that needs medical attention.

Precautions and warnings

• External use only: never swallow permethrin cream or lotion, and do not apply it inside the mouth, nose, or ears.
• Keep away from eyes: avoid contact with the eyes, and if it does get into the eyes, rinse thoroughly with clean water and seek advice if irritation continues.
• Treat close contacts too: scabies spreads through prolonged close skin contact, so family members and others who have had close contact should be checked and, if advised by a doctor, treated at the same time — otherwise the mites can simply be passed back.
• Wash bedding and clothing: as your doctor or pharmacist advises, wash clothes, bed linen, and towels used recently in hot water, since mites can survive for a short time away from the skin.
• Do not use on broken or inflamed skin beyond medical advice: tell your doctor if the skin is badly broken, infected, or very inflamed, and do not apply permethrin to open wounds unless a doctor has told you to.
• Itching may linger: itching and rash can take a few weeks to settle fully after successful scabies treatment. Do not keep reapplying permethrin repeatedly on your own — ask a doctor to check whether another treatment is needed.
• Children and infants need care: use permethrin on children only on a doctor's advice, following the pack directions for the child's age, and keep the tube out of children's reach. Avoid letting young children put treated skin in their mouths.

Interactions (general)

Because very little permethrin is absorbed through the skin, interactions with other medicines taken by mouth are unlikely. However, do not mix permethrin with other creams, lotions, or skin treatments on the same area unless your doctor tells you to, and tell your doctor if you are using any other skin medicine. Always tell your doctor and pharmacist about ALL medicines you take, including herbal and ayurvedic products, and mention any other skin treatments you are using.

Pregnancy and breastfeeding (general guidance)

Permethrin is generally considered low risk in pregnancy and breastfeeding when used as directed on the skin, because so little is absorbed, but you should still consult your doctor first if you are pregnant or breastfeeding. During breastfeeding, do not apply it on or near the nipples, and wash your hands well after use so the baby does not come into contact with the cream. Ask your doctor for guidance if you are pregnant or breastfeeding.

Storage

Store the tube or bottle at room temperature, away from heat, moisture, and direct sunlight — do not keep it in the bathroom. Keep the cap tightly closed and out of the reach of children. Do not use after the expiry date printed on the pack, and discard it once it is empty or expired.

When to see a doctor

See a doctor if the itching or rash has not improved after a few weeks, if it keeps coming back, if other family members develop similar itching, or if the skin becomes painful, oozy, crusty, or swollen. Seek urgent care for signs of a severe allergic reaction, for eye pain or vision changes after accidental contact, or if permethrin has been swallowed. If you are unsure whether the condition is really scabies or lice, see a doctor for a diagnosis before treating, rather than guessing.

FAQs

1. What is permethrin used for?

Permethrin is mainly used to treat scabies, an itchy condition caused by tiny mites burrowing into the skin, and in a weaker 1% strength it is used for head lice. It kills the mites and lice rather than just soothing the itch, so it treats the cause of the problem.

2. Why does the itching continue after treatment?

Itching often continues for a few weeks even after the mites have been killed, because the skin is still healing and the body is still reacting to the mites. This alone does not mean the treatment failed, but if itching is still severe after a few weeks, a doctor should re-examine the skin.

3. Do other family members need treatment for scabies?

Yes, usually. Scabies spreads through prolonged close skin contact, so close contacts should be checked and, if a doctor advises it, treated at the same time. Treating only one person often leads to the infestation coming back.

4. Is permethrin safe for children?

Permethrin is used in children on a doctor's advice, following the pack directions for the child's age. Keep it away from the eyes and mouth, do not let children swallow it, and ask a doctor or pharmacist if you are unsure about using it on a young child.