- Metabolite of Lichens
For Patients & Caregivers
How It Works
There is no scientific evidence to support the use of usnic acid for weight loss. Supplements containing usnic acid are associated with severe liver toxicity.
Usnic acid is a compound found in lichens. It has been used as a preservative in moisturizing creams, and as an ingredient in toothpastes, mouthwashes, and deodorants because of its antibacterial properties. Dietary supplements that contain usnic acid are promoted for weight loss but scientific evidence is lacking. The supplements have also been associated with liver toxicity.
- Weight loss This claim is not supported by scientific evidence.
- Antibacterial Usnic acid has been used in moisturizing creams, toothpastes, mouthwashes, and deodorants because of its antibacterial properties.
- Antiviral In one clinical study, an intravaginal formulation of usnic acid and zinc showed favorable results when used as an adjunct to radiosurgery in patients with human genital papillomavirus infection.
- Fever This claim is not backed by scientific studies.
- Pain relief This use is not supported by scientific evidence.
Do Not Take If
For Healthcare Professionals
Usnic acid is a secondary metabolite of lichens. Some species of lichens have been used in traditional medicine for pain relief, fever, and wound healing. Usnic acid is used as a preservative in cosmetic products. It demonstrated antioxidant (1), anti-inflammatory (2), antimicrobial (3) (4), antiproliferative and anticancer (5) (6) (7) (8), and dermal burn healing (9) properties in vitro and in animal models. A clinical study using a formulation of usnic acid and zinc showed effectiveness against genital human papillomavirus infection (10).
Over-the-counter supplements that contain usnic acid have been promoted for weight loss but scientific evidence is lacking (11). Misuse of usnic acid products has been associated with severe hepatotoxicity (12) (13) (14).
Mechanism of Action
Usnic acid has two enantiomers (+)-usnic acid and (-)-usnic acid which are thought to have different biological activities. Studies show that (+)-usnic acid has antimicrobial (3) (4), anti-inflammatory (2), and cytotoxic (5) effects while (-)-usnic acid exhibits anti-protozoan properties (15). Usnic acid can induce oxidative stress and inhibit mitochondrial function in liver cells (16) (17) which may contribute to its hepatotoxicity. However, conflicting data indicate that usnic acid protects gastric cells from drug-induced oxidative damage (1). It may inhibit prostaglandin synthesis (2).
Usnic acid demonstrated antiproliferative effects against breast cancer cells independent of p53 activity (6). In lung cancer cells, usnic acid inhibited cell growth involving G0/G1 phase cell cycle arrest and induced cell death via mitochondrial membrane depolarization and induction of apoptosis (18).
Anticoagulants: Theoretically, usnic acid may have additive effects with anticoagulant medications (14).
Cytochrome P450 3A4 substrates: In animal studies usnic acid induced CYP3A4, and may affect the intracellular concentration of drugs metabolized by this enzyme (20). Clinical relevance is unknown.