Permethrin - Uses - Dosages - Side Effects - Precautions

Permethrin: Frequently Asked Questions Answered

What is Permethrin?

Permethrin is a chemical that is used for treating parasites and insects. It is a synthetic substance that damages the nervous system and paralyses the respiratory muscles in insects. It is over a counter treatment for lice infestation. It also kills mites and is the mainline treatment for scabies. It also eggs of these parasites. It is applied topically and strictly for external use only. It is available as a cream and a lotion.

What are the uses of Permethrin?

Permethrin is used in a few of the following ways

  • Treat and prevent head lice in humans
  • Treatment of scabies – contagious skin infection caused by mites
  • Protective against mosquitoes – can be applied on clothes, mosquito nets, etc
  • Used as a disinfectant in some conditions.
  • Insect repellent
  • Used as an Insecticide 

The strength of Permethrin for treating lice is different from scabies. It has many more uses in different applications like agriculture, pets, etc.

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What are the side effects of Permethrin?

The following are a few of the side effects of Permethrin.

  • Itching of skin and scalp
  • Mild skin irritation
  • Numbness and tingling
  • Redness of the skin
  • Rash
  • Temporary stinging or burning
  • Swelling
  • Infection with pus 
  • Difficulty in breathing
  • Stomach pain

These are only a few side effects. Some of these side effects are only temporary. But you experience severe side effects like difficulty breathing, stop the medication immediately and consult the doctor.


Frequently Asked Questions about Permethrin

1. How many times can you use Permethrin cream?

Permethrin kills mites and lice after a single-use. For scabies, apply the lotion on the entire body and wash it off after a few hours. For lice, apply the lotion on wet hair and leave it for 10 minutes. Use a lice comb to remove all the dead lice.

2. Can I use Permethrin every day?

You can use Permethrin one or two times to treat scabies and head lice. If you observe live scabies mites after 14 days of application, you can use it the third time or use a different medication. It does not have a purpose for daily application.

3. What happens if you leave Permethrin cream on too long?

It is always recommended to follow the instructions on the label. It is not advisable to use more than the mentioned amount or leave it longer. If you leave it longer, you may experience itching, burning, redness, swelling, irritation, etc.

4. Is Permethrin harmful to humans?

Permethrin is absorbed into the skin. It is not harmful to humans when used as an external cream or lotion in the recommended dosage. However, if ingested, inhaled, or applied in larger amounts, you may experience side effects.

5. Is Permethrin safer than DEET?

Both DEET and Permethrin are effective insect repellents. DEET is applied to the skin, and Permethrin is applied to the clothes. However, you cannot apply Permethrin directly on the skin as an insect repellent. They are used together for better protection.

6. What is the difference between Permethrin and pyrethrin?

The main difference is that Permethrin is a synthetic chemical substance, and pyrethrin is a natural substance made from chrysanthemums. Permethrin is stable in sunlight and pyrethrin is not. Both can kill insects effectively.

7. How long does Permethrin last?

If you apply Permethrin to clothes, it can last for up to 20 days.

8. Will it rain wash away Permethrin?

No, rain does not wash away Permethrin. But during rain, it remains inactive. It becomes fully active after the rain dries.

9. How to apply Permethrin cream for lice?

First, wash your hair with only shampoo. After rinsing:

  • Apply Permethrin to the wet hair.
  • Cover the scalp and hair completely.
  • Leave it on for 10 minutes and wash it out.
  • Use a lice comb to remove all the dead lice and eggs from the hair.

10. Is Permethrin safe?

Permethrin is safe if you follow all the application directions. It can cause mild irritation. It is absorbed into the blood. Still, it is safe for adults and children over two years old.

11. Is Permethrin safe for pregnancy?

Yes, Permethrin is considered safe in pregnancy. But it is always a good idea to consult your doctor before using any medication during pregnancy. This study has concluded its safety in pregnancy.
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Disclaimer: The information provided herein is accurate, updated and complete as per the best practices of the Company. Please note that this information should not be treated as a replacement for physical medical consultation or advice. We do not guarantee the accuracy and the completeness of the information so provided. The absence of any information and/or warning to any drug shall not be considered and assumed as an implied assurance of the Company. We do not take any responsibility for the consequences arising out of the aforementioned information and strongly recommend you for a physical consultation in case of any queries or doubts.