Penile Botox has reached social media, but the science is rather more complicated than the name suggests
Botulinum toxin has already travelled from foreheads to armpits, jaws and scrotums. Its latest destination is the penis, where treatments marketed as “BoCox” promise everything from a more relaxed flaccid appearance to stronger erections.
There is some genuine research behind it. There is also a generous helping of marketing.
The quick answer
BoCox may help certain men with erectile dysfunction that has not responded to established treatments. Separate, much smaller research suggests it might reduce penile retraction, allowing the flaccid penis to hang more naturally.
BoCox may help certain men with erectile dysfunction that has not responded to established treatments. Separate, much smaller research suggests it might reduce penile retraction, allowing the flaccid penis to hang more naturally.
It has not been shown to permanently enlarge the penis, and evidence that it increases erect length is lacking. It remains an off-label, non-standardised treatment without enough evidence for the European Association of Urology to recommend it in routine clinical practice (EAU, 2026).
What is it?
BoCox is a commercial nickname rather than one clearly defined procedure.
Some providers use it to describe botulinum toxin injected into the erectile tissue of the penis to investigate erectile dysfunction. Others use it for injections targeting penile retraction and flaccid appearance.
That distinction matters. Treating erectile function and trying to create a more relaxed flaccid hang are different objectives involving different tissues.
It is also different from Scrotox, where botulinum toxin is administered to the scrotal area.
How does it work?
When the penis is flaccid, smooth muscle within the erectile tissue remains relatively contracted. During an erection, that muscle relaxes, arteries widen and the erectile chambers fill with blood.
Botulinum toxin may reduce the release of norepinephrine, one of the chemical signals encouraging contraction. Think of it as easing a partially applied handbrake. It cannot manufacture a bigger vehicle, but it might allow the existing machinery to move more freely.
When targeting retraction, the theory is that relaxing the dartos tissue reduces the tendency of the penis to pull tightly towards the body.
What does the evidence actually show?
A 2009 pilot study treated ten men who were dissatisfied with pronounced flaccid penile retraction but had normal erect lengths. Seven reported improvement. However, the average objectively measured increase in ordinary flaccid length was only 2.5 mm. There was no improvement in stretched or erect length, and the effect had disappeared by six months (Shaeer et al., 2009).
Research into erectile dysfunction is more substantial. Two randomised trials studied men whose erectile dysfunction had not responded adequately to tablets such as sildenafil or tadalafil, and in some cases conventional penile injections.
One trial involving 176 men found that both 50-unit and 100-unit onabotulinumtoxinA groups improved compared with saline placebo. Around 40% achieved a clinically meaningful improvement, with the higher dose appearing to last longer (El-Shaer et al., 2021).
A 2025 systematic review found two randomised trials and four retrospective studies. Across the two trials, botulinum toxin improved the SHIM erectile-function score by an average of 4.35 points over placebo at 12 weeks. The review described the results as promising but stressed the limited number of studies, varying protocols and need for better long-term evidence (Pang, 2025).
What are the risks, limitations or unanswered questions?
Reported study complications have mostly been uncommon and local, including penile pain, bruising and prolonged erections. One case of priapism was reported in the 2025 review.
That does not establish long-term safety. Researchers still need to determine the most appropriate toxin, dose, technique, treatment interval and patient group.
Penile treatment is not included among the UK-licensed indications for BOTOX. It is therefore off-label. Off-label treatment is not automatically improper, but it places greater responsibility on the practitioner to justify it, explain the uncertainty and provide appropriate monitoring (MHRA, 2014).
What should clients know or ask?
Ask:
What exactly is the treatment intended to improve?
Is the injection targeting erectile dysfunction or flaccid retraction?
Is it off-label, and has that been clearly explained?
What evidence supports the dose and technique being proposed?
Who has assessed the possible cause of erectile dysfunction?
What happens if prolonged erection, infection or another complication occurs?
Any new erectile difficulty should be properly assessed. It can sometimes be associated with cardiovascular, hormonal, neurological, psychological or medication-related factors. A catchy treatment name should not replace a diagnosis.
What should practitioners learn?
Practitioners should not treat “BoCox” as though it were simply Scrotox moved a few centimetres north.
The available studies involve specific products, doses, anatomy and patient groups. Botulinum-toxin units are not interchangeable between brands (AbbVie, 2026).
Safe provision would require an appropriate treatment, evidence-based justification, specific off-label consent, relevant anatomical competence, confirmed insurance, documented follow-up and a credible complication plan, including management of priapism.
Frequently asked questions
Does BoCox permanently enlarge the penis?
No. There is no good evidence that it creates permanent increases in penile length or girth.
Can BoCox make the flaccid penis look longer?
Possibly, by reducing retraction. The only direct pilot study involved ten men and found a modest average improvement under ordinary conditions.
Can BoCox improve erections?
Early trials suggest it may help some men with difficult-to-treat erectile dysfunction. It is not established as a routine alternative to properly assessed first-line treatments.
Is BoCox the same as Scrotox?
No. Scrotox involves the scrotal area. BoCox involves penile tissue and may be intended to address either erectile function or penile retraction.
Is BoCox licensed in the UK?
Botulinum toxin products are licensed for several conditions, but penile retraction and erectile dysfunction are not listed indications. This use is off-label.
My honest opinion
I find the research genuinely interesting, particularly for men with erectile dysfunction who have exhausted established options. However, that is very different from selling it to healthy men as an enlargement treatment.
For flaccid retraction, ten participants and an average improvement of 2.5 mm are enough to justify further research, not extravagant promises. For erectile dysfunction, the evidence is stronger but still insufficiently developed for routine recommendation.
I will continue watching the research, but at the moment, the name is doing rather more heavy lifting than the evidence.
Written by Injector Rick, founder and aesthetic practitioner at BONAVADA Aesthetics in Worthing.
The science is interesting, but for now, keep your expectations strictly flaccid.
References
AbbVie (2026) BOTOX 100 Allergan Units: Summary of Product Characteristics. Electronic Medicines Compendium.https://www.medicines.org.uk/emc/product/859/smpc
Accessed 10 August 2026
El-Shaer, W., Ghanem, H., Diab, T., Abo-Taleb, A. and Kandeel, W. (2021) Intra-cavernous injection of BOTOX® (50 and 100 Units) for treatment of vasculogenic erectile dysfunction: randomized controlled trial. Andrology, 9(4), 1166 1175.https://doi.org/10.1111/andr.13010
Accessed 10 August 2026
European Association of Urology (2026) Management of Erectile Dysfunction. EAU Guidelines on Sexual and Reproductive Health.https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/management-of-erectile-dysfunction
Accessed 10 August 2026
Medicines and Healthcare products Regulatory Agency (2014) Off-label or unlicensed use of medicines: prescribers’ responsibilities. GOV.UK.https://www.gov.uk/drug-safety-update/off-label-or-unlicensed-use-of-medicines-prescribers-responsibilities
Accessed 10 August 2026
Pang, K.H. (2025) The effectiveness and safety of intracavernosal botulinum toxin injections in the management of erectile dysfunction: a systematic review and meta-analysis of clinical studies. Sexual Medicine, 13(2), qfaf034.https://doi.org/10.1093/sexmed/qfaf034
Accessed 10 August 2026
Shaeer, O., Shaeer, K. and Shaeer, A. (2009) Botulinum toxin A (Botox) for relieving penile retraction. Journal of Sexual Medicine, 6(10), 2788–2794.https://doi.org/10.1111/j.1743-6109.2009.01434.x
Accessed 10 August 2026