Ivermectin Mite Work

April 4, 2014

Ivermectin Mite Work

  1. Mark V. Dahl, MD

Topical ivermectin 1% cream was effective for clearing papulopustular rosacea, and its antiparasitic action may be why.

  1. Mark V. Dahl, MD

Studies of papulopustular rosacea patients show increased incidence of demodex mite infestation, and when present, mite density in the follicles is increased compared with controls. The Demodex folliculorum mite lives head-down in the follicle, where it feeds on sebum, shed skin cells, and other co-inhabitants of the infested follicle. A causal relationship of demodex to papules, pustules, and other skin manifestations of rosacea has not been proved. Ivermectin kills some parasites, so investigators studied whether topical ivermectin might reduce rosacea papules and pustules in two phase III, multicenter, randomized, double-blind, parallel-group, vehicle-controlled studies with identical protocols.

A total of 683 patients with moderate-to-severe facial rosacea and 15 to 70 inflammatory papules and pustules were randomized to apply either ivermectin cream 1% or vehicle cream to the face at bedtime for 12 weeks. Results were similar in both trials. About 40% of ivermectin cream users were “clear or almost clear” after 12 weeks, versus about 15% of users of vehicle alone (P<0.001). By week 12, the median percentage decrease from baseline in the number of inflammatory papules was greater with ivermectin (76% and 75%) than with vehicle (50% in both studies; P<0.001). The percentage of patients who self-rated their improvement as excellent or good was greater with ivermectin than with vehicle (69% and 66% vs. 39% and 34%, respectively; P<0.001). There were no severe adverse effects.


Ivermectin 1% cream seems to be safe and effective for papulopustular rosacea. The study was not designed to correlate efficacy with mite infestation or density, so we do not know if all responders had infestations before treatment. Ivermectin's mechanism of action suggests that demodex mites might cause papules and pustules, but ivermectin has anti-inflammatory actions as well as antiparasitic ones, down-regulating both interleukin-1b and tumor necrosis factor-α.

Editor Disclosures at Time of Publication

  • Disclosures for Mark V. Dahl, MD at time of publication Consultant / Advisory board Genentech; Makucell, Inc.; Mayo Clinic Equity Elorac, Inc.; Johnson & Johnson; Pfizer Speaker's bureau Los Angeles Dermatological Society; University of Southern California Editorial boards UpToDate


Reader Comments (1)

JEFFERSON DICKEY Physician, Internal Medicine

Why was the vehicle so effective?

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