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Permethrin for scabies and lice

by egpat         23 May 2024

What is this drug, permethrin? Actually, this drug acts as a pesticide or insecticide, and this compound belongs to the chemical category of pyrethroids. These are a group of compounds; among them, permethrin is one of the insecticides that is used by topical route in order to treat scabies, which is caused by itching mites. So permethrin can control the scabies and itching caused by these mites by inhibiting their neuronal excitation, thereby paralyzing the skeletal muscle. Similarly, permethrin can also be used for the treatment of head lice, where it can be applied by lotion to treat these lice.

How to apply for head lice

For the treatment of head lice, the entire hair should be thoroughly washed and dried. During this hair wash, shampoo can be used, but conditioner should not be used, which reduces the effectiveness of permethrin. After a thorough wash and drying of the hair, permethrin lotion can be applied.

Permethrin is also available as a cream, but lotion is preferred for the treatment of head lice. So this lotion should be thoroughly applied to the hair so that it is completely distributed on the entire scalp. At the same time, this lotion should not be applied to other parts of the body in order to eliminate the irritation produced by this drug.

So after thorough distribution of this lotion throughout the scalp, it should be left for 10 minutes, and after that, the permethrin can be thoroughly washed with warm water. So this removes the paralyzed head lice by washing with warm water, but the eggs of the lice may still remain on the scalp as well as the hair.

Finally, a head lice comb can be used to remove any remaining lice as well as nits that are attached to the hair and scalp. So with these four steps, the maximum number of head lice can be removed. However, the success of the treatment depends on other factors.

Whatever accessories are going to be used during this application, such as combs or any plastic appliances, towels, and bed sheets, all should be thoroughly washed with hot water in order to completely eliminate the paralyzed lice, and this permethrin lotion can also be applied after one week if any further symptoms of lice are present on the head.

How to apply for scabies

Similarly, this can be used for the treatment of scabies, where, in step one, the entire body should be thoroughly washed and dried. It can be applied to the skin in the form of cream, which is available at five percent strength.

Now the cream can be applied thoroughly to the entire skin, from head to toe, such that it is uniformly distributed. Then it should be left for at least 8 to 14 hours. After that, it can be thoroughly washed and cleaned so that itching mites can be removed from the body.

The chemical nature of permethrin

Permethrin is a pyrethroid derivative. It has ester functionality attached to a cyclopropane ring. So this is first carbon, second carbon, and third carbon.It has 2,2-dimethyl cyclopropane, which forms an ester. It is a 2,2-dimethylcyclopropan-1-carboxylate derivative.


When permethrin is applied topically, it can produce some local effects, resulting in hypersensitive reactions. Initially, it can cause erythema and pruritus, resulting in increased itching. It can also produce some edema. That's why when this drug is used for the treatment of scabies for the first three weeks, the symptoms may increase due to the local reactions produced by permethrin.

Similarly, when this permethrin is accidentally applied to the eye, it can produce eye irritation. So that's why, when this drug is used, avoid contact with the eye, mouth, nose, and vagina. Permethrin can also produce some difficulty breathing, which is more important for patients with asthma. So this drug should be carefully used in patients with asthma or any respiratory disorders.

Permethrin should be carefully given to pregnant women as well as breastfeeding women, where it may increase toxic reactions. So caution should be taken when it is applied to pregnant women. Similarly, this drug is not indicated for infants under the age of less than two months.

Side effects

Permethrin produces local side effects. It can produce some pruritus, local irritation, erythema, skin rashes, some numbness, and tingling sensations.


Permethrin is available as a lotion, particularly in a one percent solution, and this lotion can be used for the treatment of lice. Similarly, it is also available as a cream at a strength of five percent, and this cream is particularly used for the treatment of scabies.

In this way, permethrin can be used for the treatment of lice as well as scabies, but care should be taken to avoid severe hypersensitive reactions. This drug should not be in contact with the eye, mouth, nose, or vagina. Initially, this drug can increase itching sensations, edema, and local irritation, but after a few weeks of treatment, these symptoms can be reduced.