Are there any "unsafe" herbs?

There are some herbs that are considered unsafe in particular situations:

n Licorice -- This is used for ulcers, as an expectorant and for cancer prevention. It is unsafe for use in people who have cirrhosis, kidney disease and heart disease, as well as in women who are pregnant. To minimize the risk of adverse effects, licorice should be used for no longer than 6 weeks.

n Ephedra -- Ephedra is used as a decongestant and anorexiant (appetite suppressant), as well as for allergies, asthma and depression. It is a component of the herbal phen-fen, and has been associated with increased blood pressure, as well as an increased incidence (frequency) of tremors, seizures, stroke, heart attacks and even death.