The Chinese Pharmacopoeia stipulates that the dosage of comfrey decoction is 5~10g; ‘Appropriate amount for external use, boiled ointment or applied by soaking in vegetable oil. The specific dosage should be adjusted according to the condition and physique, and patients should follow the doctor’s instructions for medication. Comfrey has the efficacy of clearing heat and cooling blood (relieving blood heat by clearing heat), activating blood circulation and detoxification, penetrating rashes and eliminating spots. It is good at clearing heat in the blood, and can promote blood circulation to detoxify and penetrate rashes. It is suitable for the symptoms of blood-heat and toxicity, purple and black spots and rashes, sores and ulcers, impenetrable measles, eczema, and scalded by water and fire. Comfrey is cold and slippery in nature, easy to hurt the spleen and stomach yang qi, so it is used with caution for people with cold spleen and stomach (spleen and stomach weakness and cold) and loose stools. If you need to use the drug, you should choose the drug usage and dosage under the guidance of a doctor, do not blindly self-medication, so as not to cause adverse consequences.