Can a Man Get an Erection Without Testicles?

Erections are possible without testicles, though they become harder to achieve and maintain over time. The mechanism behind an erection is fundamentally a nerve-and-blood-vessel event, not a hormonal one, which means the basic plumbing still works even after the body’s main testosterone factory is removed. In a small study of castrated men shown erotic visual material, a quarter achieved a functional erection. The reality, though, is more layered than a simple yes or no, because testosterone influences nearly every tissue involved in the process, and its absence gradually reshapes the landscape.

Why Erections Do Not Depend Entirely on Testosterone

An erection begins when the autonomic nervous system signals blood vessels in the penis to relax and fill with blood. Parasympathetic nerves running from the lower spinal cord trigger this relaxation, while sympathetic nerves generally work in the opposite direction, promoting detumescence. Muscles around the base of the penis then contract to help trap the blood inside, creating rigidity.¹ This entire cascade is a vascular and neurological reflex. Testosterone does not flip the switch; nerves and blood flow do.

Animal research has demonstrated this directly. In rats castrated for up to seven weeks, electrical stimulation of the pelvic nerves still produced a rise in pressure inside the erectile tissue, confirming that an androgen-independent component of the erectile response exists.² The erection was weaker and shorter-lived than in intact animals, but it happened. The reflex arc from nerve signal to blood vessel dilation does not require testosterone to fire. It just fires less effectively without it.

What Testosterone Actually Does to the Erectile Process

If testosterone is not the on-switch, what role does it play? A systematic review in a major urology journal concluded that testosterone modulates nearly every component involved in erectile function, from the nerve clusters in the pelvis to the smooth muscle and the lining of blood vessels inside the erectile chambers.³ Think of it less as a light switch and more as the electrical grid that keeps the lights bright and reliable.

One of the most important things testosterone does is maintain levels of nitric oxide, the chemical messenger that tells smooth muscle in the penis to relax and let blood rush in. In castrated rats, researchers observed a gradual decline in the nerve fibers that produce nitric oxide, and the decline tracked with how long the animals had been without testosterone. When testosterone was given back, those nerve fibers recovered and erectile pressure returned to near-normal values.⁴ Separate work confirmed that castrated rats had lower activity of the enzyme that produces nitric oxide and lower concentrations of the downstream signaling molecule that relaxes smooth muscle. Testosterone treatment reversed both deficits.⁵

At the molecular level, the story centers on gene expression. Castrated rats showed lower messenger RNA levels for the neuronal form of the nitric oxide-producing enzyme compared to testosterone-treated castrated rats. When researchers provided a nitric oxide donor drug directly, it boosted erectile pressure in castrated animals but not in testosterone-replete ones, suggesting the castrated animals were specifically deficient in nitric oxide availability.⁶ So testosterone keeps the nitric oxide pipeline well stocked. Without it, the pipeline runs dry over weeks to months, making erections progressively weaker.

Evidence From Men Who Have Lost Their Testicles

The most direct human evidence comes from men treated for prostate cancer, where removing testosterone is a primary strategy to slow the disease. In a survey of 201 men on androgen deprivation therapy (about 70% receiving chemical castration via drugs and 30% having undergone surgical removal of the testicles), 81% reported erectile dysfunction.⁷ That means roughly one in five still had some erectile ability, which is consistent with a broader review of the literature on androgen deprivation and sexual function that found about 20% of patients maintained some degree of libido and erectile capacity.⁸

A smaller but revealing study tested 16 surgically castrated men with visual erotic stimulation and found that four of them, or 25%, achieved a functional erection.⁹ These were men whose testicles had been removed, not men on drugs that suppress testosterone. The fact that any of them responded to visual stimulation alone underscores that the brain-to-penis nerve pathway can drive an erection without gonadal testosterone in the picture.

The Psychological Piece Is Bigger Than You Might Expect

An interesting finding from research on chemical castration complicates the picture further. In one study, erectile deterioration occurred in about 70% of patients on chemical castration, but the researchers concluded this was largely due to lost sexual interest and lost confidence in being able to get an erection, rather than a physical inability to do so.¹⁰ In other words, the brain stopped sending the signal because desire had evaporated, not because the penis could no longer respond.

This makes sense when you consider that testosterone is deeply involved in libido. A man who no longer feels sexual desire rarely encounters situations that test whether his erection hardware still works. The loss of drive can be so thorough that many men on androgen deprivation therapy describe a kind of emotional flatness around sex, which effectively takes erections off the table long before any structural changes in penile tissue would. Separating “can’t get aroused” from “can’t get erect” is difficult in practice, but the evidence suggests both are happening, and the motivational loss often comes first.

The Adrenal Backup Supply

The testicles are not the only organs that produce testosterone. The adrenal glands, which sit on top of the kidneys, also make small amounts. In men who had undergone surgical castration for prostate cancer, researchers measured testosterone levels in blood draining from the adrenal glands and found clear evidence of adrenal testosterone production.¹¹ The adrenals did not ramp up production to compensate for the lost testicles, but they kept making what they had always made. That trickle of adrenal testosterone is far too low to maintain normal male testosterone levels, but it may be one reason some castrated men retain partial erectile function.

Animal research adds a related detail. After surgical castration, the adrenal glands significantly increased their output of DHEA, a precursor hormone that the body can convert into small amounts of testosterone and other androgens.¹² Whether this adrenal compensation is enough to meaningfully support erectile tissue in humans remains unclear, but it likely contributes to the low residual androgen levels seen in castrated men and helps explain why the erectile response does not vanish entirely.

What Happens to Penile Tissue Over Time Without Testosterone

If the hormonal absence persists, the structural consequences in the penis become harder to ignore. Androgen deprivation leads to a loss of smooth muscle in the erectile chambers, increased deposition of fibrous connective tissue, changes in the structure of the nerves running along the top of the penis, and accumulation of fat cells in areas that should contain elastic, blood-trapping tissue.¹³ Smooth muscle is critical because it is what relaxes to allow blood in and then compresses veins to keep blood trapped. When smooth muscle is replaced by collagen and fat, the tissue cannot expand properly, and blood leaks out too easily.

This remodeling helps explain why erections in castrated animals are not just weaker but also shorter. In castrated dogs, erectile pressure reached only about 57% of systolic blood pressure, compared with 80% in intact dogs, and the erections faded faster because venous outflow from the erectile chambers was higher.¹⁴ The tissue could still fill with blood, but it could not hold it. Over time, this structural decay worsens, which is why the question of whether a castrated man can get an erection does not have a fixed answer. It depends on how long ago the testicles were removed, the man’s age, his baseline vascular health, and how much residual androgen his adrenal glands produce.

A related finding from the same animal model showed that the common erectile dysfunction drug class (PDE5 inhibitors like sildenafil or vardenafil) failed to improve erections in castrated animals.¹³ These drugs work by amplifying the nitric oxide signal, but if the underlying nitric oxide supply and smooth muscle architecture are degraded, there is not enough signal left to amplify. This has direct clinical implications for men after orchiectomy who try standard ED medications and find them ineffective.

Treatment Options for Men After Orchiectomy

For men who have lost their testicles to cancer treatment and want to preserve or regain erectile function, the approach depends on the medical situation. If the reason for castration was prostate cancer, testosterone replacement is usually off the table because it could fuel the disease. If the castration happened for another reason, such as testicular cancer with bilateral involvement, testosterone replacement therapy can restore erectile function. In rats, even delayed testosterone replacement after weeks of castration recovered the nerve fibers responsible for nitric oxide production and restored the centrally driven erectile response.¹⁵

In clinical settings, androgen supplementation has been shown to improve nocturnal erections, sexual function, mood, and energy in men with testosterone deficiency.¹⁶ For men with low testosterone who do not respond to PDE5 inhibitors alone, combining testosterone therapy with these drugs has shown promise. Data from placebo-controlled trials suggested that transdermal testosterone improved the response to sildenafil in men with low-normal testosterone levels, though one study showed the benefit was significant only at four weeks, not at twelve.¹⁷ The combination is worth discussing with a doctor, particularly for men whose testosterone levels are borderline rather than absent.¹⁸

When testosterone replacement is not an option and medications do not work, mechanical and surgical interventions remain available. Vacuum erection devices create an erection by drawing blood into the penis with negative pressure and then trapping it with a constriction band. These work regardless of hormonal status because they bypass the nerve-signaling pathway entirely. Inflatable penile prostheses are another option and tend to have higher satisfaction rates than other forms of ED therapy among men who choose them.¹⁹ For a man without testicles who wants reliable erections and cannot use hormones, a prosthesis is often the most dependable route.

Erections After Orchiectomy in Transgender Women

A separate population that sheds light on this question is transgender women who undergo bilateral orchiectomy as part of gender-affirming care. These women are typically already on estrogen-based hormone therapy that suppresses testosterone, and the orchiectomy removes the remaining testicular source. A recent study found that the combination of gender-affirming hormone therapy plus orchiectomy significantly reduced spontaneous erections compared to hormone therapy alone, but did not eliminate erections during sexual arousal or activity.²⁰

For some transgender women, the persistence of erections after orchiectomy is unwanted and distressing. For others, it may be a neutral or even welcome finding. Either way, this data reinforces the core physiological point: the erectile reflex can survive the loss of the testicles and the near-elimination of testosterone, particularly when there is active sexual arousal driving the neural component. The erections tend to be less firm and less frequent, but the capacity persists in at least a meaningful subset of people.

Why PDE5 Inhibitors Often Fail After Castration

One of the more frustrating realities for men who lose erectile function after orchiectomy is that the most commonly prescribed ED pills may not work well for them. As the animal research demonstrated, both surgical and chemical castration reduced erectile pressure during nerve stimulation, and the PDE5 inhibitor vardenafil did not rescue the response in either group.¹³ The researchers concluded that the problem was not primarily about enzyme activity but about structural damage: the smooth muscle loss and connective tissue buildup in the erectile chambers created a vascular leak that no amount of chemical signaling could overcome.

This explains a frustrating clinical pattern where men are prescribed sildenafil or tadalafil after androgen deprivation and find them disappointing. The drugs are designed for a system where the hardware is intact but the signal is weak. After prolonged testosterone deprivation, the hardware itself deteriorates. For men in this situation, the combination approach of restoring testosterone (when medically safe) while also using PDE5 inhibitors addresses both the signal deficit and, over time, the structural one. When testosterone is contraindicated, the conversation shifts to mechanical solutions or prostheses rather than continuing to escalate pill dosages that cannot fix the underlying tissue problem.

The Timeline Matters

How long a man has been without his testicles shapes the answer to this question more than almost any other variable. In the weeks immediately after orchiectomy, the neural reflex is largely intact and some men continue to have erections, particularly in response to strong arousal cues. The rat data showed that erectile pressure declined gradually over the first 30 days post-castration, not all at once.⁴ By seven weeks, an androgen-independent baseline remained but was clearly diminished.²

The encouraging news is that some of this damage appears reversible if testosterone is restored. Even after prolonged deprivation in animal models, testosterone replacement recovered both the nerve fibers and the erectile response, though peripheral recovery lagged behind central improvements.¹⁵ There are limits to this reversibility, and the longer the deprivation lasts, the more fibrous remodeling occurs that may not fully reverse. But the window for recovery is wider than many men assume, and the literature does not support the idea that a few months without testosterone permanently destroys erectile capacity.