A medicinal plant with analgesic (painkilling) and anti-inflammatory magic properties. It contains allantoin and rosmarinic acid that are probably responsible for its soothing power. It's often used in the field of sports for treating bruises or sprains.
The questionable side of comfrey (that prevented us from giving it a goodie rating) is that it also contains pyrrolizidine alkaloids (PA). That guy has some proven toxic effect so for example in Germany the permissibale dose of PA is 100 μg/day and if the dose is between 10-100 μg/day the treatment is limited to 4-6 weeks per year.
But do not panic: most probably your skincare product does not contain anywhere near that dose. For example, a German sport-ointment to treat ankle sprains contains only 0.35 μg/g PA, so even with four uses per day, the dose is way below 10 μg/g. The same is probably true for your skincare product.
Show me some proof
- Phytomedicine, Volume 11 (6) - Sep 20, 2004, Efficacy and tolerance of a comfrey root extract (Extr. Rad. Symphyti) in the treatment of ankle distorsions: results of a multicenter, randomized, placebo-controlled, double-blind study