Abstract: A topical composition for treating or preventing acne vulgaris which comprises at least one saturated or unsaturated chain alcohol having 18 carbon atoms represented by formula (1): ##STR1## wherein a dotted line represents either the presence or the absence of a double bond as an active ingredient, makes it possible to inhibit proliferation of Propionibacterium acnes, which causes acne vulgaris, or kill the bacterium to effectively treat or prevent acne vulgaris. The compound represented by formula (1) can be easily synthesized and has an extremely low toxicity. Furthermore, it exerts an excellent antibacterial effect on Propionibacterium acnes even when used at a relatively low concentration. Thus it can be used only in a small amount , which ensures a high safety.

Abstract: An acne vulgaris treating and preventing topica, which comprises, as an active ingredient, at least one compound selected from the group consisting of caryophyllene, cedrene, longifolene and thujopsene. The topica exhibits sufficient inhibitory activity on proliferation of Propionibacterium acnes, a pathogenic bacterium causing acne vulgaris, at a small therapeutic dose without causing skin irritation.

Abstract: An acaricidal composition is disclosed, comprising one or more compounds selected from among methyl cinnamate, ethyl cinnamate, n-propyl cinnamate, isopropyl cinnamate, n-butyl cinnamate, isobutyl cinnamate, isoamyl cinnamate, n-hexyl cinnamate, allyl cinnamate, cinnamyl acetate, cinnamyl propionate, cinnamyl n-butyrate, cinnamyl isobutyrate, p-cresyl acetate, p-cresyl butyrate, p-cresyl isobutyrate, p-methylbenzyl propionate, .beta.-phenoxyethyl alcohol, phenoxyethyl acetate, phenoxyethyl propionate, phenoxyethyl n-butyrate, phenoxyethyl isobutyrate, methyl phenylacetate, ethyl phenylacetate, dibenzyl ether, heliotropin, methyl diphenyl ether and 2-methyl-1-methylbicyclo[2.2.1]hept-5-en-2-yl)-1-penten-3-ol as an active ingredient.