Priapism is a persistent, often painful erection that occurs without or long after sexual stimulation. The most dangerous type is ischaemic priapism, where blood is trapped in the penis and cannot drain, starving the tissue of oxygen. The longer it lasts, the greater the risk of permanent damage and future erectile dysfunction.
Causes include some medications, erectile dysfunction drugs or injections, certain blood disorders such as sickle cell disease, recreational drugs, alcohol, and sometimes trauma. Men with sickle cell disease are at particular risk and may experience recurrent episodes.
Do not wait to see if it settles. If an erection lasts more than four hours, go to an emergency department or call your local emergency number right away. Treatment is more effective the sooner it is given, so timing genuinely matters.