Usnea (Old Man's Beard)
Usnea spp. — also: Old man's beard, Beard lichen
Genuine lab-level antimicrobial activity (usnic acid); human evidence is lacking and internal safety is a real concern.
A lichen used across Europe, China, and the Americas as a wound dressing and for respiratory/urinary infections.
Topical antimicrobial; traditional internal use for respiratory and urinary infections.
Usnic acid has documented antibacterial activity in vitro; double-extraction is traditional (water + alcohol).
- Topical antimicrobial for minor wounds
- Traditional respiratory/urinary use
In vitro antibacterial data (usnic acid); no solid human trials.
- No human efficacy data
- Internal safety unclear
- Liver toxicity (concentrated/internal)
- Contact allergy
- Pregnant people; anyone with liver concerns; long-term internal users
Usnic acid has been linked to LIVER TOXICITY in concentrated supplement form (notably weight-loss products); allergy/contact dermatitis.
Avoid combining with other liver-stressing substances.
Avoid in pregnancy and with any liver condition.
Slow-growing lichen — harvest only fallen material sustainably; identify carefully (stretchy white inner cord is the test).
A real antimicrobial of the lichen world — best respected as a topical; internal usnic acid carries genuine liver-toxicity reports.