Priapism is the medical term to describe an erection from Hell: it is prolonged, painfull, and may cause permanent damage to the tissues of the penis (including impotence or even gangrene). Men are advised to listen to the advice in the commercials - errections lasting more than 4 hours should receive immediate medical attention.

Priapism is independent of sexual desire - it is a problem of the blood vessels. A number of medicines and diseases can cause priapism. It is a rare complication of drugs that enhance errections (Viagra, Bois Bande). Although priapism is listed as a potential side effect of Viagra, it appears that long term use of that drug actually improves blood flow and reduces recurrent priapism. Antidepressant medications (SSRIs) have also been linked to this condition, as have drugs that work on the adrenaline receptors. In most cases where a drug leads to priapism, there is an underlying condition brought to the surface by the medicine.

Priapism can be caused by any disease that increases coagulation of the blood and traps blood in the penis; these included sickle cell disease, thrombosis, phlebitis and anti-phospholipid syndrome.

There are two basic types of priapism, and they require different treatments. In low-flow priapism a blockage leads to poor circulation and a risk of oxygen deprivation. In high-flow priapism, more blood is moving through the penis, but the pressure is still high enough to cause tissue damage over time.

This condition is named after the Greek fertility god Priapus; statues from ancient Greece always depict him with a rock-hard erection (some lasting for thousands of years).

Priapism of the clitoris is also possible, but the female variety of prolonged swelling is far less common.

---

Bibliography

PubMed PMID 16756894 Priapism: Diagnosis and Treatment.

PubMed PMID 11939691 Citalopram-induced priapism / Trazodone.

PubMed PMID 16698365 Long-term oral phosphodiesterase 5 inhibitor therapy alleviates recurrent priapism.

PubMed PMID 16709221 Priapism of the Clitoris.

PubMed PMID 12423816 Clitoral priapism: a rare condition presenting as a cause of vulvar pain.