Benefits

We found one systematic review (search date 1997) that examined four trials. In each case a single application of treatment was given unless stated otherwise. One study (150 adults and children) compared 5% permethrin cream with 10% crotamiton cream (a non-insecticide) and 1% lindane lotion.8 It used clinical features as the measure of success. The results showed that permethrin was slightly, but not significantly, more likely to cure (49/50 (98%) people with permethrin versus 44/50 (88%) with crotamiton; relative risk (RR) 1-11, 95% confidence intervals (CI) 1-0-1-2). The same study also found permethrin to be significantly more effective than lindane: permethri n cured 49/50 (98% ) whereas lindane cured only 12/50 (24%) people (RR 4-08: CI 2-5-6-7).8 A single randomised controlled trial (RCT) comparing 5% permethrin cream with 10% crotamiton cream evaluated cure by elimination of parasites.9 It found permethrin to be more effective after 14 and 28 days. After 14 days 33/47 (70%) of people in the permethrin group and 41/47 (87%) in the crotamiton group still had lesions. At this point 10 people in the crotamiton group were withdrawn from the study because their infestation was exacerbated. However, after 28 days 42/47 (89%) people in the permethrin group were free from parasites compared with 28/47 (60%) in the crotamiton group (RR 1-5, CI 1-2-1-9).9 This study also recorded patients' subjective reports on the persistence of pruritus, which was found to be closely related to effectiveness of the treatments.

Two trials compared the effect of 5% permethrin cream with that of 1% lindane lotion. A small study (46 people) found fewer people improved 14 days after using permethrin (13/23 (57%) versus lindane 20/23 (87%); P<0-02), but a significantly better rate of cure, by parasitological examination, for permethrin at 28 days (21/23 versus 15/23; P<0-025, RR 1-4, CI 1-0-1-9).10 A larger trial (467 people) did not identify parasites but recorded a significant decrease in the number of lesions persisting in both groups after 14 ± 3 days. At 28 ± 7 days success rates were 181/199 (91%) after using 5% permethrin cream, compared with 176/205 (86%) after using 1% lindane lotion (P = 0-18, RR 1-06, CI 0-9-1-1).11 At final assessment, significantly fewer of the permethrin group (27/194 (14%)) had persistent itch compared with 49/197 (25%) of the lindane group (P= 0-007).11

The systematic review identified no RCTs comparing 0-5% malathion, in either aqueous or alcohol vehicles, with other treatments. Case series and one quasi-randomised trial suggest that it is effective, with a cure rate of over 80% at 4 weeks.12-14

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