Background: Contact dermatitis by cosmetics is due to both irritation and delayed type hypersensitivity, which manifests various conditions including acneiform eruptions. Cosmetics are nowadays extensively tested for the comedogenicity, so they are infrequent cause of acneiform eruptions. Meanwhile, the incidence of the high oil concentration products (ex. water-in-oil emulsions)-induced acneiform eruptions seems to be increasing. Objectives: To review the clinical findings of acneiform eruptions caused by oil-type cosmetics and acne vulgaris. Methods: We evaluated 20 patients who were diagnosed as oil-type cosmetics-induced acneiform eruptions (Contact folliculitis group, CF group). As a control, 20 acne patients were included. The CF group stopped the oil-type products, and both groups were treated with minocycline. Underlying skin disorders, oil-type cosmetics used by patients, the treatment periods and the investigator’s global assessment (IGA) etc. were evaluated. Results: A total of forty patients (mean age 29.0 ± 11) were analyzed. In the CF group, the average time taken to “almost clear” was 21.4 days. It was shorter than that of the control group (p < 0.05). The average of IGA score was decreased from 2.97 to 0.46 at 2W later visit. The number of comedons and inflammatory papules were also decreased (p < 0.05). Conclusion: Acneiform eruptions, a low grade irritant contact folliculitis, caused by oil-type cosmetics can be improved within a short time only if the patients stop using the causative oil products. To check the patient’s daily care products is important to avoid unnecessary over-treatment misdiagnosing the transient irritant contact folliculitis as chronic acne vulgaris.