Usnic acid

Purported Benefits, Side Effects & More
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This information describes the common uses of Usnic acid, how it works, and its possible side effects.
Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.

What is it?

There is no scientific evidence on usnic acid for weight loss, and supplements containing it have been 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.

What are the potential uses and benefits?

  • 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 small study, an intravaginal formulation of usnic acid and zinc showed favorable results when used along with radiosurgery for HPV infection.
  • Fever
    This claim is not backed by scientific studies.
  • Pain relief
    This use is not supported by scientific evidence.

What are the side effects?

  • Usnic acid can cause liver damage when used in high doses.
  • Allergic reactions have been reported with topical use.

What else do I need to know?

Patient Warnings:

Weight loss supplements containing usnic acid are associated with severe liver toxicity.

Do Not Take if:

You are taking anticoagulants: Theoretically, usnic acid may have additive effects with anticoagulant medications.
You are taking CYP450 3A4 substrate drugs: Animal studies suggest usnic acid can decrease the effects of such drugs. Clinical relevance is not known.