Blisters on the foreskin then possible causes: first, if excessive masturbation or have local contusions, then tension blisters can appear. The combination of bleeding can be manifested as blood blisters, mostly with a relevant medical history, such as irritation or trauma. A single blister can usually be healed by local disinfection with a disinfectant solution and by keeping local irritation down. Secondly, the appearance of a herpes virus infection can appear after the redness of the foreskin. The blisters on the glans are mostly clustered, accompanied by local redness and pain, and after the herpes breaks down, it can appear as erosion with pain. Herpes virus testing is needed to further confirm the diagnosis. Thirdly, if you have a foreskin infection or a sexually transmitted disease, it can lead to local blisters, accompanied by abnormal urination with local swelling and pain. Related pathogenic tests, such as bacteriological tests, mycoplasma, chlamydia and gonococcal tests are needed to rule out.