Priapism — a prolonged, often painful erection lasting more than 4 hours — is the side effect that appears in every ED medication commercial. It sounds dramatic because it is. But the fear of priapism is often disproportionate to the actual risk, and understanding what it involves can replace anxiety with preparedness.
How Common Is It?
Ischemic priapism from PDE5 inhibitors is rare. Population-based studies estimate the incidence at approximately 1–3 per 100,000 patient-years of PDE5 inhibitor use. You are more likely to get a hole-in-one in golf than to experience priapism from properly dosed sildenafil or tadalafil.
The risk is higher with intracavernosal injection therapy (Trimix) — estimated at 1–3% of injections, primarily when doses are being titrated — which is why initial dosing is always done in a urologist's office.
Why 4 Hours Is the Cutoff
The 4-hour threshold isn't arbitrary. Ischemic priapism means blood is trapped in the corpus cavernosum without circulation — it's deoxygenated, acidotic, and slowly damaging the smooth-muscle tissue. Research shows:
- Under 4 hours: Tissue damage is typically minimal and reversible
- 4–12 hours: Progressive smooth-muscle damage begins. Treatment at this stage usually preserves long-term function
- 12–24 hours: Significant tissue necrosis may occur. Long-term erectile function is increasingly at risk
- Beyond 24 hours: Irreversible corporal damage is likely. Penile prosthesis may eventually be needed
What the ER Does
If you present to an emergency department with priapism, the treatment protocol is straightforward:
Step 1: Aspiration. Using a large-bore needle (typically 18-gauge) inserted into the corpus cavernosum, the ER team aspirates (removes) the trapped, deoxygenated blood. This immediately reduces pressure and often resolves the erection.
Step 2: Phenylephrine injection. If aspiration alone doesn't resolve the priapism, phenylephrine (a sympathomimetic vasoconstrictor) is injected directly into the corpus cavernosum. This constricts the smooth muscle and forces blood out. Doses are given every 3–5 minutes until the erection subsides, with blood pressure monitoring.
Step 3: Surgical shunt (rare). If aspiration and phenylephrine fail — extremely uncommon — a surgical shunt procedure creates a drainage channel between the corpus cavernosum and the corpus spongiosum or a vein, allowing trapped blood to escape.
What to Tell the ER
- When the erection started
- What medication you took, the dose, and when you took it
- Whether you used recreational drugs (particularly cocaine or poppers)
- Any history of sickle cell disease or blood disorders
- Whether the erection is painful (ischemic priapism is typically painful; non-ischemic is typically painless)
Don't be embarrassed. ER teams handle priapism regularly and the treatment is time-sensitive. Every minute you spend debating whether to go to the ER is a minute of additional ischemic damage.