Phellodendron Bark may cause black stools, but most often resolves when the medication is discontinued. Huangbai is a Chinese herb with a yellow-brown or yellow-brown appearance, a bitter taste, cold nature, and belongs to the kidney and bladder meridians. Its effects are clearing heat and drying dampness (removing heat and drying dampness), laxing fire and removing vapor, and detoxifying and healing sores. It can be used to treat wet sores, night sweating (abnormal sweating after going to sleep and stopping sweating after waking up) seminal emission, etc. Generally, black stools may appear after taking it, but it can be relieved after stopping the medicine. If the patient in the emergence of black stool, after stopping the drug did not see relief, and accompanied by abdominal pain, perianal discomfort and other symptoms, consider rectal polyps, hemorrhoids and other causes, to the hospital in a timely manner to timely diagnosis, identify the cause of the disease. Phellodendron Bark should be taken under the guidance of a doctor, avoid taking medication privately, allergies, spleen and stomach cold (spleen and stomach weakness and cold) of the population to prohibit the use of. Daily attention should be paid to regular observation, keep the perianal environment clean, eat more fiber-rich food, etc..