Some patients and doctors swear by the healing power of herbs and other plants, but their chemical complexity makes them notoriously difficult to study.

Some headway is being made, however, as WSJ's In The Lab column reports. New research suggests a four-herb combination long used in traditional Chinese medicine helps curb some side effects of chemotherapy.

Another example of an herbal treatment breaking into the halls of Western medicine is that of ingenol mebutate, a skin cream that is extracted and purified from the dried Euphorbia peplus plant, commonly known as petty spurge. The cream gets rid of precancerous skin lesions and prevents their recurrence, according to recent research published in the New England Journal of Medicine.

Denmark-based LEO Pharma produces the cream, which was approved in January by the FDA, under the brand name Picato.

The plant itself was used as a home remedy for skin conditions in Australia, says Mark Lebwohl, first author on the study and chairman of the dermatology department at the Mount Sinai School of Medicine. It grows everywhere, "including the sidewalks of Manhattan," he tells the Health blog.