The Priapus Shot (P-Shot) for Erectile Dysfunction
The Priapus shot (P-shot) is an intracavernosal injection of platelet-rich plasma (PRP) marketed for erectile dysfunction, but current evidence shows only modest, inconsistent benefits with no established role in evidence-based guidelines—it should be considered experimental and not recommended as standard treatment.
What is the P-Shot?
The P-shot involves autologous platelet-rich plasma injections into the penile corpora cavernosa, typically administered as a series of 3 injections spaced 2-4 weeks apart. 1, 2 The theoretical mechanism relies on growth factors within PRP promoting tissue regeneration, angiogenesis, and vasculogenesis in damaged penile tissue. 3, 4
Evidence for Efficacy in Erectile Dysfunction
Limited Clinical Data
The only pilot study specifically evaluating P-shot for vascular ED showed minimal benefit: 15 patients with vascular ED unresponsive to PDE5 inhibitors received 3 PRP injections and achieved a modest 5-point IIEF-EF improvement at 1 month, declining to only 3 points at 6 months (P=0.022). 2
Functional outcomes remained poor: Only 26.7% of patients could maintain erections long enough for intercourse after treatment versus 20% before, a clinically insignificant difference (P=1). 2
The first double-blinded RCT was recently published showing some evidence of efficacy, but systematic reviews conclude that recommendations cannot be made due to scarce evidence and lack of standardized protocols. 1, 3
Quality of Evidence Issues
All studies suffer from critical methodological flaws: Small cohorts, lack of blinding or placebo controls, short follow-up periods, and no standardization of PRP preparation or injection technique. 1, 4
The evidence base remains insufficient: Multiple systematic reviews from 2020-2022 consistently conclude that while PRP may be "promising," no clinical recommendations can be made for ED treatment. 1, 3, 4
Safety Profile
No major complications have been reported in available studies. 1, 2, 4
Minor side effects are uncommon: Mild penile bruising, ecchymosis, and hematomas have been noted in Peyronie's disease studies (where more data exists), with transient hypotension in 2 of 90 patients. 1
The procedure appears safe but lacks long-term safety data. 4, 5
Clinical Context and Recommendations
Established First-Line Treatments Should Be Used Instead
PDE5 inhibitors (sildenafil, tadalafil, vardenafil, avanafil) remain first-line therapy for erectile dysfunction with robust evidence supporting their use. 6
Second-line options include intraurethral alprostadil, intracavernosal injections of vasoactive agents, or vacuum devices—all with substantially more evidence than PRP. 6
When P-Shot Might Be Considered
Only as part of clinical trials with standardized protocols to better understand its potential role. 1
Patients should be counseled that this is experimental therapy with modest effects at best, particularly for vascular ED. 2
The treatment may have slightly better evidence for Peyronie's disease than for ED, though still limited. 5
Critical Pitfalls to Avoid
Do not offer P-shot as a proven alternative to established ED treatments—the evidence does not support this positioning. 1, 2
Avoid commercial marketing claims—the rapid commercial availability has outpaced scientific validation. 3
Do not assume all PRP preparations are equivalent—lack of standardization in preparation methods makes comparing studies impossible. 1, 4
Recognize that any modest improvements may not be clinically meaningful—statistical significance does not equal clinical significance when functional outcomes (ability to have intercourse) remain largely unchanged. 2