Mouth herpes does not heal on its own in 3 days, but it is possible for it to heal in about 5-15 days. 1. Herpes of the mouth is a self-limiting disease and can be categorized into herpes simplex and viral herpes according to the cause of herpes of the mouth. Herpes simplex will heal on its own but is prone to recurrence. Generally speaking, herpes simplex can be cured in about 5 to 7 days. 2. Viral herpes can be cured in about 7 to 15 days if the condition is not serious and the body’s immunity is very good, and there is a possibility of self-healing. If the condition is serious, it can be treated with antiviral drugs such as acyclovir and topical acyclovir cream. If the symptoms of discomfort should consult a doctor in time, so that the diagnosis can be clear, so that the disease can be better faster, but also to avoid the delay of the disease, the use of drugs need to follow the doctor’s instructions.