Scabies: Why New Rashes Appear After Permethrin Treatment

Scabies rash

Hello Doctor, I have been treating scabies for about a month.
For the first two weeks, I applied BB lotion daily but still developed rashes.
Later, the doctor prescribed permethrin, and on the day I applied the medication, I washed my sheets and clothes in a high-temperature dryer for 30 minutes.
However, the night after applying the medication, I developed two new red rashes, and the following night, I had three more new red rashes.
I have heard that permethrin is a very effective insecticide that can even kill insect eggs, so why am I still getting new rashes so soon? The medication can only be reapplied after a week, so what should I do if new rashes keep appearing during this time? Also, I would like to know if the effectiveness of permethrin lasts for a month; otherwise, why do I need to wait a week before the next application? Please help me understand, Doctor.
Thank you!

Wo, 20~29 year old female. Ask Date: 2020/06/14

Dr. Wu Yuxin reply Dermatology

I'm not sure why you're experiencing a rash, as I haven't seen the actual lesions.
Permethrin is generally an insecticide.
For clinical issues, you should consult your attending physician, as they are most familiar with your condition.

Reply Date: 2020/06/14

More Info

Scabies, caused by the Sarcoptes scabiei mite, can be a persistent and frustrating condition to treat. Permethrin is a topical insecticide that is commonly used to treat scabies by killing the mites and their eggs. However, it is not uncommon for patients to experience new rashes or lesions even after treatment with permethrin. There are several reasons why this might occur.

Firstly, it is important to understand that while permethrin is effective at killing the mites, it does not immediately alleviate the symptoms associated with scabies. The itching and rash can persist for several weeks after treatment due to the body's inflammatory response to the mites and their waste products. This means that even after the mites are dead, the skin may still react, leading to the appearance of new rashes or the persistence of existing ones.

Secondly, it is possible that the new rashes you are experiencing are not due to a reinfestation of scabies but rather a result of the skin's reaction to the previous infestation. The immune system may continue to react to the remnants of the mites or their eggs, causing inflammation and new lesions. This is often referred to as post-scabetic pruritus, where itching and rashes continue even after successful treatment.

Another factor to consider is the possibility of reinfestation. If you have close contact with someone who has scabies or if contaminated items (like bedding or clothing) were not adequately treated, there is a risk of getting reinfested. Although you mentioned that you washed and dried your bedding and clothing at high temperatures, it is crucial to ensure that all items that may have come into contact with the mites are treated properly.

Regarding the timing of the next application of permethrin, it is typically recommended to wait one week before reapplying the treatment. This is because the medication needs time to work effectively, and reapplying too soon may not provide additional benefits. The effectiveness of permethrin can last for several days, but it is not guaranteed to last for an entire month. Therefore, if symptoms persist or worsen, it is essential to consult your healthcare provider for further evaluation and potential alternative treatments.

In the meantime, if you are experiencing new rashes, it is advisable to avoid scratching, as this can lead to secondary infections. Over-the-counter antihistamines may help alleviate itching, and topical corticosteroids can reduce inflammation. However, these should be used under the guidance of a healthcare professional.

In summary, the appearance of new rashes after permethrin treatment for scabies can be attributed to several factors, including the body's inflammatory response, potential reinfestation, and the need for time for the skin to heal. If you continue to experience issues, it is crucial to follow up with your healthcare provider for a thorough assessment and tailored treatment plan.

Similar Q&A

Persistent Scabies: Understanding Symptoms and Treatment Challenges

Since mid-November, after being discharged from surgery, I have developed a rash on my body. (I suspect it was during my hospitalization when a nurse helped me tie my hair; she had just changed the bed linens for the patient next door and didn't remove her gloves before comi...

Dr. Wu Yuxin reply Dermatology
Without actually seeing the lesion, it is impossible to make a definitive diagnosis. If it is causing significant distress, please seek medical attention as soon as possible.

Understanding Scabies Symptoms: What to Watch For After Exposure

Hello, doctor. I have a history of contact with a scabies patient. I started using Permethrin cream (BID) the day after the exposure because I was very worried, and occasionally I applied it TID. After 2 to 3 days, I noticed several bite-like lesions on my thighs, and I have abou...

Dr. Wu Yuxin reply Dermatology
Based on the literal description, it is not possible to confirm the condition without actually seeing the lesion. It is recommended to have a physician evaluate it for proper assessment.

Is My Scabies Relapsing? Understanding Symptoms and Treatment

I have been undergoing treatment for scabies for two weeks. Since applying the medication, there have been no new rashes, and my skin only occasionally experiences mild itching. I initially thought I was close to recovery (I have been consistently applying the medication), but in...

Dr. Yang Zhiya reply Dermatology
Scabies can recur, and it is generally assessed by checking for the appearance of new similar rashes in common areas affected by scabies (such as the hands, armpits, elbow creases, abdomen, genitals, and groin) or by evaluating the response after administering scabicidal medicati...

Understanding Scabies: Recurrence, Allergies, and Treatment Options

I previously underwent treatment for scabies and had a week of relief, but it seems I have been reinfested with scabies mites as I am experiencing frequent itching. I would like to ask: 1. How can I determine if this is a recurrence of scabies or an allergic reaction to the dead ...

Dr. Zhang Zhibo reply Dermatology
Hello: The best treatment for scabies is continuous treatment for at least 2-3 weeks. If new rashes appear two weeks after a single treatment, it indicates that there are still remaining mites on the body, and a second treatment is necessary. If there is only itching, it may indi...