In traditional Chinese medicine Corydalis (Yan Hu Suo) is a rhizome considered to be the best, just behind opium, in herbal relief of pain. It is said to have between 1-10% the analgesic potency of opium, without any of the addictive side effects. In fact, Corydalis and the opium poppy (Papaver somniferum) belong to the same plant family, the Papaveraceae family.