A bunch of small blisters under your nose could be trauma, herpes simplex. 1.Trauma. External forces, such as burns and scalds, cause a bunch of small blisters under the nose. The blisters caused by external forces are usually larger, with thinner walls and clear-colored liquid inside. 2. Herpes simplex. Infected by herpes simplex virus, viral herpes may appear under the nose, mainly manifested as localized erythema, pimples, irritating blisters, and there is a significant tingling sensation when touching with hands. Most patients with blisters under the nose are considered to be related to herpes virus infection. It is recommended to go to the dermatology department of the hospital, under the guidance of the doctor to give acyclovir and other antiviral ointment topical application, can help improve.