After the occurrence of mouth ulcers, you cannot use Yunnan Baiyao aerosol or capsules externally, but you can take Yunnan Baiyao capsules orally. Yunnan Baiyao includes many medicines, such as Yunnan Baiyao aerosol, Yunnan Baiyao capsule, etc. If pain occurs, such as back pain, when the skin is not broken, you can use Yunnan Baiyao aerosol externally, which is able to make the pain relief. However, if mouth ulcers occur, Yunnan Baiyao aerosol can not be applied at this time, and Yunnan Baiyao capsule is not recommended, which has no obvious effect on the treatment of mouth ulcers. When mouth ulcers occur, if local bleeding occurs, you can take oral Yunnan Baiyao capsules for treatment, Yunnan Baiyao capsules have the effect of hemostasis, can make the bleeding gradually stop. The drug should be applied under the guidance of a doctor.