Background: Genetic and environmental components may contribute to acne causation.

Objective: We sought to assess the impact of family history, personal habits, dietary factors, and menstrual history on a new diagnosis of moderate to severe acne.

Methods: We conducted a case-control study in dermatologic outpatient clinics in Italy. Cases (205) were consecutive those receiving a new diagnosis of moderate to severe acne. Control subjects (358) were people with no or mild acne, coming for a dermatologic consultation other than for acne.

Results: Moderate to severe acne was strongly associated with a family history of acne in first-degree relatives (odds ratio 3.41, 95% confidence interval 2.31-5.05). The risk was reduced in people with lower body mass index with a more pronounced effect in male compared with female individuals. No association with smoking emerged. The risk increased with increased milk consumption (odds ratio 1.78, 95% confidence interval 1.22-2.59) in those consuming more than 3 portions per week. The association was more marked for skim than for whole milk. Consumption of fish was associated with a protective effect (odds ratio 0.68, 95% confidence interval 0.47-0.99). No association emerged between menstrual variables and acne risk.

Limitations: Some degree of overmatching may arise from choosing dermatologic control subjects and from inclusion of mild acne in the control group.

Conclusions: Family history, body mass index, and diet may influence the risk of moderate to severe acne. The influence of environmental and dietetic factors in acne should be further explored.