Recently, I received a letter from a patient who wrote, “I am suffering from impotence, so I listened to a doctor who injected a drug called poppy base into my penis, and got an erection for 4 hours after the first injection and 6 hours after the second injection. Will there be any problems with this injection? Is it harmful to have an erection for too long?” This is a very representative question, and it is necessary to give you a detailed explanation. There are many treatments for ED, one of which is the injection of drugs into the cavernous body of the penis. The drugs available for injection include poppies, phentolamine, prostaglandin E1, etc. This method of intracavernosal injection was once popular, but is now used sparingly because long-term injections can cause problems such as fibrosis of the penile corpus cavernosum and persistent penile erection. When it is needed in certain cases, the dose should be strictly controlled, starting with a small dose and figuring out an effective dose, otherwise it is very likely to cause persistent erection. According to our clinical observation, after the injection of the above drugs into the cavernous body of the penis, the penis can generally be erected for 1~2 hours. If the erection does not subside for more than 4 hours, it should be treated urgently; otherwise, swelling, bruising, or even necrosis and fibrosis occur in the penis. We have encountered several such cases in which persistent erection occurred after penile cavernous body injection in foreign hospitals, and because of the lack of timely treatment, the persistent erection had exceeded 20 hours when referred to our hospital, losing the best time for treatment, and despite the many measures we took, the treatment was not effective and the penis eventually became necrotic and fibrotic. Therefore, we emphasize here that once a persistent erection occurs after intracavernosal injection, it should be treated urgently at a regular hospital as soon as possible. Treatment measures include intracavernosal injection of vasoconstrictive drugs, aspiration of intracavernosal stasis, and even surgical treatment. As long as the treatment is timely, the problem can usually be solved.