Scabies is an intensely itchy parasitic infection of the skin caused by the Sarcoptes scabiei mite. It is a common public health problem with an estimated global prevalence of 300 million cases. Serious adverse effects have been reported for some drugs used to treat scabies.
To evaluate topical and systemic drugs for treating scabies.
In June 2010, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2010, Issue 2), MEDLINE, EMBASE, LILACS, and INDMED. In August 2010, we also searched the grey literature and sources for registered trials. We also checked the reference lists of retrieved studies.
Randomized controlled trials of drug treatments for scabies.
Data collection and analysis
Two authors independently assessed trial quality and extracted data. Results were presented as risk ratios with 95% confidence intervals and data combined where appropriate.
Twenty-two small trials involving 2676 people were included. One trial was placebo controlled, 18 compared two or more drug treatments, three compared treatment regimens, and one compared different drug vehicles.
Fewer treatment failures occurred by day seven with oral ivermectin compared with placebo in one small trial (55 participants). Topical permethrin appeared more effective than oral ivermectin (140 participants, 2 trials), topical crotamiton (194 participants, 2 trials), and topical lindane (753 participants, 5 trials). Permethrin also appeared more effective in reducing itch persistence than either crotamiton (94 participants, 1 trial) or lindane (490 participants, 2 trials). No difference was detected between permethrin (a synthetic pyrethroid) and a natural pyrethrin-based topical treatment (40 participants, 1 trial), and between permethrin and benzyl benzoate (53 participants, 1 trial), however both these trials were small.
No significant difference was detected in the number of treatment failures between crotamiton and lindane (100 participants, 1 trial), lindane and sulfur (68 participants, 1 trial), benzyl benzoate and sulfur (158 participants, 1 trial), and benzyl benzoate and natural synergized pyrethrins (240 participants, 1 trial); all were topical treatments. No trials of malathion were identified.
No serious adverse events were reported. A number of trials reported skin reactions in participants randomized to topical treatments. There were occasional reports of headache, abdominal pain, diarrhoea, vomiting, and hypotension.
Topical permethrin appears to be the most effective treatment for scabies. Ivermectin appears to be an effective oral treatment. More research is needed on the effectiveness of malathion, particularly when compared to permethrin, and on the management of scabies in an institutional setting and at a community level.
Plain language summary
Scabies is a parasitic infection of the skin. It occurs throughout the world, but is particularly problematic in areas of poor sanitation, overcrowding, and social disruption, and is endemic in many resource-poor countries. The global prevalence of scabies is estimated at 300 million cases, but the level of infection varies between countries and communities. The female mite burrows into the skin to lay eggs which then hatch out and multiply. The infection can spread from person to person via direct skin contact, including sexual contact. It causes intense itching with eruptions on the skin. Various drugs have been developed to treat scabies, and herbal and traditional medicines are also used. The review of trials attempted to cover all these. The authors identified 22 small trials involving 2676 people, with 19 of the trials taking place in resource-poor countries. Permethrin appeared to be the most effective topical treatment for scabies, and ivermectin appeared to be an effective oral treatment. However, ivermectin is unlicensed for this indication in many countries. Adverse events such as rash, vomiting, and abdominal pain were reported, but the trials were too small to properly assess serious but rare potential adverse effects. No trials of herbal or traditional medicines were identified for inclusion.
Strong, M.; Johnstone, P. Interventions for treating scabies. Cochrane Database of Systematic Reviews (2007) (Issue 3) Art. No.: CD000320. [DOI: 10.1002/14651858.CD000320.pub2]