Having an erection all day long is considered abnormal. Generally, if the penis stays erect for more than 4 hours, it is an abnormal erection. The danger of abnormal erection is relatively large, it may lead to continuous engorgement of the penis, and may even lead to penile necrosis, so this situation needs to be taken seriously. It is advisable to go to the hospital for examination and treatment in time. If you are diagnosed with abnormal penile erection, you need to take means to change the erection of the penis. You can use cold water to stimulate, and if the erection does not dissipate with cold water, you can bleed the penis and glans to reduce the degree of erection.