Cell proliferant, stimulates quick healing of strains and slow-healing wounds (for external use only) when used internally, comfrey is potentially harmful: there are reports of liver toxicity. some preparations contain significant levels of alcohol ; they should be used with caution. Monitor patients for abdominal distention, nausea, abdominal pain, and elevated liver function test results. Limit use to 4-6 wk/yr to prevent exposure to large amounts of toxic alkaloids