Does Tadalafil Increase Testosterone Levels?

Tadalafil can raise testosterone levels modestly in certain men, but the effect is neither universal nor dramatic. The clearest evidence comes from men who already have low testosterone alongside metabolic problems like obesity and insulin resistance. In healthier men with normal hormone levels, the needle barely moves. What makes the picture interesting is that tadalafil appears to interact with hormone pathways in ways that go beyond simply improving erections, including shifting the balance between testosterone and estrogen and possibly influencing how cells respond to androgens.

What the Clinical Evidence Actually Shows

The strongest signal for a testosterone boost comes from men with erectile dysfunction and metabolic syndrome. In one study of this population, daily tadalafil at 5 mg raised mean total testosterone from about 3.6 to 5.2 ng/mL over three months, a jump of roughly 40 percent. Luteinizing hormone (LH), the pituitary signal that tells the testes to make testosterone, actually decreased during that period, suggesting the testes were producing more testosterone per unit of stimulation rather than being driven harder by the brain.¹ A separate study in a similar group found testosterone climbed from 4.25 to 4.71 ng/mL at three months and 5.11 at six months, confirming the trend persists with continued use.²

A head-to-head comparison of tadalafil and sildenafil found that both drugs increased total testosterone and decreased LH in men with erectile dysfunction, though tadalafil showed a somewhat larger effect.³ These results are consistent across several small trials, but they share an important limitation: the men enrolled typically had low baseline testosterone and metabolic dysfunction. The findings do not necessarily apply to men starting from a normal hormonal baseline.

Why the Effect Looks Different in Healthier Men

When researchers have studied tadalafil in men without metabolic syndrome, the testosterone picture changes. A pilot study tracking men on long-term tadalafil found no significant change in total or free testosterone levels over 12 months. What did change was the ratio of testosterone to estradiol. Estrogen levels dropped, so even though absolute testosterone stayed roughly the same, the hormonal environment shifted in a more androgen-favoring direction.⁴

A safety trial in healthy men specifically looking at reproductive parameters found that tadalafil had no detrimental effect on reproductive hormones at all, meaning no notable increase or decrease.⁵ This is reassuring from a safety standpoint, but it reinforces the point: if your testosterone is already where it should be, tadalafil is unlikely to push it higher in a meaningful way.

The pattern makes biological sense. Men with metabolic syndrome tend to carry excess visceral fat, which actively converts testosterone into estrogen through an enzyme called aromatase. If tadalafil suppresses that conversion, the men with the most active aromatase have the most room for improvement. Men with less body fat and lower aromatase activity simply have less testosterone being lost to conversion in the first place.

How PDE5 Inhibition Interacts with Hormone Production

Tadalafil’s primary job is blocking PDE5, an enzyme that breaks down a signaling molecule called cGMP. In the penis, more cGMP means better blood flow and firmer erections. But PDE5 exists in tissues throughout the body, and cGMP signaling turns out to be relevant to testosterone production in ways researchers are still mapping out.

The cells that manufacture testosterone in the testes, called Leydig cells, use cGMP as part of their internal machinery. Laboratory studies have shown that when PDE5 is blocked and cGMP accumulates, Leydig cells ramp up their production of steroid hormones. This happens through a protein called StAR, which acts as a gatekeeper for cholesterol entering the pathway that ultimately produces testosterone. Higher cGMP levels lead to more StAR activity, which means more raw material enters the production line.⁶ Animal research with sildenafil, a related PDE5 inhibitor, showed that chronic treatment boosted testosterone output from Leydig cells and raised serum testosterone substantially in mice.⁷⁸

Whether this Leydig cell stimulation translates into clinically meaningful testosterone increases in humans is where things get murky. The animal studies use doses and durations that don’t map directly onto the 5 mg daily regimen most men take. The mechanism is real, but it may contribute only a small fraction of the testosterone changes seen in clinical studies, with other pathways doing more of the heavy lifting.

The Aromatase Connection

One of the more intriguing mechanisms involves aromatase, the enzyme that converts testosterone into estradiol. Cell studies have shown that tadalafil can suppress aromatase expression at both the gene and protein level. In human bone-like cells, tadalafil reduced aromatase activity while simultaneously increasing androgen receptor expression and decreasing estrogen receptor expression.⁹ The net effect is a cellular environment that favors androgen signaling over estrogen signaling.

This may partly explain why tadalafil’s testosterone-raising effect is most pronounced in men with metabolic syndrome. Visceral fat is loaded with aromatase, and animal research suggests tadalafil may reduce visceral fat accumulation by improving insulin sensitivity and promoting the conversion of white fat cells (which are metabolically sluggish and aromatase-rich) into brown fat cells (which burn energy and express less aromatase).¹⁰ If tadalafil shrinks the tissue that converts testosterone to estrogen, more testosterone remains in circulation. A review paper has described tadalafil as potentially acting as a “selective modulator of steroid hormone production” across fat, bone, and prostate tissue, though the authors note most of the supporting evidence is still from lab and animal models rather than large clinical trials.¹¹

In non-obese men with mild erectile dysfunction, daily tadalafil improved lean body mass and reduced estradiol, consistent with the aromatase-suppression theory playing out even in men who are not significantly overweight.¹² The estradiol reduction may matter as much as any testosterone increase, because the balance between the two hormones influences sexual function, body composition, and mood more than either level in isolation.

Does Resuming Sexual Activity Itself Raise Testosterone?

This is a confounding factor that rarely gets enough attention in discussions of tadalafil and testosterone. Research has shown that men who become sexually inactive due to erectile dysfunction experience a drop in testosterone that reverses once sexual activity resumes, regardless of which treatment restored function. In one study, men who regained normal sexual activity after various impotence therapies saw dramatic increases in both total and free testosterone, while men whose treatments failed showed no hormonal change.¹³

This creates an attribution problem in tadalafil studies. If a man starts taking tadalafil, his erections improve, he resumes regular sexual activity, and his testosterone goes up, how much of that hormonal change came from the drug’s pharmacology and how much from the behavioral shift? Most of the clinical trials reporting testosterone increases with tadalafil did not control for changes in sexual frequency. The honest answer is probably “both,” but we cannot cleanly separate the contributions. If you are considering tadalafil specifically to raise your testosterone, keep in mind that part of any benefit may come from what the drug enables you to do rather than from the molecule itself.

What Tadalafil Does at the Receptor Level

Blood testosterone levels are only part of the hormonal story. Equally important is how strongly cells respond to whatever testosterone is circulating. In vitro experiments have found that tadalafil increases the expression of androgen receptors in muscle cells, with exposure to tadalafil roughly tripling androgen receptor mRNA and boosting the expression of myogenin, a protein involved in muscle cell development.¹² If these cell-culture findings translate to living tissue, tadalafil could amplify the effect of existing testosterone without necessarily increasing its concentration in the blood.

This might help explain why some men report feeling benefits from tadalafil that go beyond erections, like improved energy or body composition, even when their blood testosterone levels remain unchanged. The evidence here is still early-stage and mostly from lab experiments rather than controlled human trials, so it would be premature to treat tadalafil as a functional androgen booster. But the receptor data adds a layer to the conversation that simple blood tests miss.

When Tadalafil Is Combined with Testosterone Therapy

For men with genuinely low testosterone, the clinical question is often not whether tadalafil raises testosterone but whether adding it to testosterone replacement therapy (TRT) produces better results than either treatment alone. Several studies have tested this combination, and the answer is consistently yes for sexual function.

Testosterone regulates the production of nitric oxide synthase, the enzyme that starts the chain of events tadalafil depends on. Men with very low testosterone often respond poorly to PDE5 inhibitors alone because there isn’t enough nitric oxide being produced for the drug to amplify.¹⁴ A study of men who had previously failed to respond to PDE5 inhibitors found that adding testosterone supplementation and then reintroducing tadalafil produced meaningful improvements in erectile function, especially in men whose testosterone had been severely depleted.¹⁵

A trial using injectable testosterone plus daily tadalafil found sustained improvements in erectile function that persisted even after treatment stopped, suggesting the combination may have lasting effects on the underlying physiology rather than just masking symptoms.¹⁶ A crossover study confirmed that the vast majority of men preferred the combination of testosterone replacement and tadalafil over either treatment alone.¹⁷

There is a practical takeaway here: if you have low testosterone and tadalafil alone is not working well for erectile dysfunction, the evidence supports discussing combination therapy with your doctor. The relationship runs both ways. Testosterone makes tadalafil work better, and tadalafil may modestly support testosterone levels as part of a broader treatment strategy. A pooled analysis of clinical trials found that men with low testosterone had a significantly smaller improvement in erectile function scores on tadalafil compared to men with normal testosterone, reinforcing that the drug’s effectiveness depends partly on hormonal context.¹⁸

Fertility and Reproductive Safety

Men concerned about testosterone sometimes worry that any drug affecting hormones might impair fertility. With tadalafil, the evidence is reassuring. A placebo-controlled study in men aged 45 to 75 found no significant differences in sperm concentration, motility, morphology, or total sperm count between tadalafil and placebo groups over six months of daily use.¹⁹ An earlier safety trial confirmed that tadalafil had no adverse effects on spermatogenesis or reproductive hormones.⁵

This stands in contrast to exogenous testosterone therapy, which suppresses sperm production and can cause infertility during use. If you are a man trying to maintain or improve testosterone levels while preserving fertility, the fact that tadalafil nudges hormones without shutting down the body’s own production system is a meaningful distinction. Tadalafil does not replace testosterone replacement therapy for men with clinically diagnosed hypogonadism, but for men with borderline levels and metabolic issues, it offers a milder intervention that does not carry the fertility trade-off.

Who Is Most Likely to See a Testosterone Effect

Pulling together the evidence, the men most likely to experience a meaningful testosterone increase from tadalafil share a cluster of characteristics: they carry excess visceral fat, have features of metabolic syndrome like insulin resistance or elevated triglycerides, and start with testosterone levels in the low or borderline range. The more aromatase activity your body has, and the more testosterone is being lost to conversion, the more room tadalafil has to work by suppressing that conversion and possibly by stimulating Leydig cell output directly.

Men who are lean, metabolically healthy, and have normal baseline testosterone should not expect tadalafil to push their levels notably higher. They may still benefit from the shift in the testosterone-to-estrogen ratio, and they might see improvements in lean mass and endothelial function, but their blood testosterone number on a lab report is unlikely to change enough to matter. The drug remains excellent for its approved purpose in these men, but it is not a backdoor testosterone booster for someone whose hormones are already in a healthy range.

One lingering question is whether the doses studied, almost always 5 mg daily, represent the threshold for hormonal effects or whether higher doses would produce different results. No published trials have systematically compared tadalafil doses for their testosterone impact. The on-demand doses sometimes prescribed for sexual activity (10 or 20 mg taken as needed) would not produce the sustained PDE5 inhibition that the aromatase and Leydig cell mechanisms likely require, so daily dosing appears to be a prerequisite for any hormonal benefit.