Terpenes are a broad class of naturally occurring organic compounds produced by many plants, including cannabis, citrus, pine, and many herbs. Some terpenes, such as limonene, pinene, and linalool, have attracted scientific attention for their potential anti-inflammatory, antimicrobial, and antioxidant properties. These biological activities are relevant to the pathophysiology of acne, which involves inflammation and proliferation of Cutibacterium acnes on the skin.

Several in vitro studies have demonstrated that select terpenes exhibit antibacterial activity against acne-associated bacteria. For example, tea tree oil (rich in the terpene terpinen-4-ol) has shown moderate efficacy in reducing acne lesions in some small human studies, likely due to its antimicrobial and anti-inflammatory effects. Limonene and alpha-pinene have also been reported to inhibit bacterial growth and reduce inflammation in laboratory models. However, most of the evidence is limited to laboratory and animal studies, with few robust, large-scale human trials.

Overall, while there is some scientific rationale and preliminary evidence supporting the use of certain terpenes in acne management, the clinical data are still limited and inconsistent. More rigorous human studies are needed to establish standardized formulations, dosing, safety, and efficacy. Thus, the evidence rating is moderate to low at this time.