From the Guidelines
If you're experiencing continuous itching after scabies treatment, this is likely post-scabies syndrome, which can persist for 2-4 weeks after successful treatment. The persistent itching occurs because your body is still reacting to dead mites and their waste products, even though the active infestation has been treated 1. According to the 2015 sexually transmitted diseases treatment guidelines, symptoms or signs persisting for >2 weeks can be attributed to several factors, including treatment failure or faulty application of topical scabicides 1.
Management of Continuous Itching
To manage the continuous itching, consider the following:
- Continue using prescribed medications like permethrin 5% cream as directed by your healthcare provider
- For symptom relief, try antihistamines such as cetirizine (10mg daily) or diphenhydramine (25mg every 6 hours as needed)
- Apply calamine lotion or hydrocortisone 1% cream to itchy areas 2-3 times daily
- Moisturize with fragrance-free lotions after bathing
- Wash all clothing, bedding, and towels in hot water and dry on high heat
- Vacuum your living space thoroughly
Retreatment and Follow-Up
If itching worsens, new burrows appear, or symptoms don't improve after 4 weeks, consult your healthcare provider as you might need retreatment or have a different skin condition 1. Retreatment 2 weeks after the initial treatment regimen can be considered for those persons who are still symptomatic or when live mites are observed, and an alternative regimen is recommended for those persons who do not respond initially to the recommended treatment 1.
From the FDA Drug Label
Patients may experience persistent pruritus after treatment. This is rarely a sign of treatment failure and is not an indication for retreatment. In clinical trials, approximately 75% of patients treated with permethrin cream, 5% who continued to manifest pruritus at 2 weeks had cessation by 4 weeks.
- Continuous itching after scabies treatment with permethrin cream, 5% is a common occurrence and is rarely a sign of treatment failure.
- It is not an indication for retreatment, and in most cases, the itching will stop by 4 weeks after treatment 2, 2.
From the Research
Causes of Continuous Itching after Scabies Treatment
- Post-scabies itch can persist for several weeks to months after successful treatment of scabies 3
- The main manifestation of scabies infection is intense itching, which may persist even after treatment 3
- In rare cases, post-scabies itch can progress into a delusional parasitosis related to scabies 3
Treatment Strategies for Continuous Itching
- Treatment of scabies according to guidelines and additional recommendations should result in effective curing, even in cases thought to be intractable 4
- Topical application of permethrin is the first line therapy for scabies, with other options including systemic ivermectin and topical crotamiton or benzyl benzoate 4
- A combination of permethrin and ivermectin is used to treat otherwise intractable cases and is generally indicated for the treatment of crusted scabies 4
Factors Contributing to Treatment Failure
- Improper application of external agents, failure of repeated treatment with ivermectin, and incomplete decontamination of furnishings and clothes can contribute to treatment failure 4
- Failure to simultaneously treat contact persons and absence of written documents explaining treatment modalities can also lead to treatment failure 4
- Resistance of scabies mites to permethrin has not been directly proven, but there is a rising number of well-documented cases of poor response to this agent 4
Comparison of Treatment Efficacy
- Topical permethrin was equally effective or more effective than crotamiton or benzyl benzoate in treating scabies 5
- Topical permethrin and systemic ivermectin did not differ substantially in efficacy, with single and double administrations of ivermectin being similarly effective 5
- Systemic ivermectin was found to be superior to topical permethrin in trials involving entire populations with a high prevalence of scabies 5