Tadalafil can modestly increase testosterone levels, though it’s not a testosterone therapy and wasn’t designed for that purpose. Several clinical studies show measurable rises in total testosterone during daily tadalafil use, with the effect appearing stronger than with similar medications like sildenafil. The increase stays within normal physiological range and likely results from multiple overlapping mechanisms rather than a single direct hormonal action.
What the Clinical Data Shows
In a study of men with metabolic syndrome taking 5 mg of tadalafil daily, mean testosterone values rose from 3.6 to 5.2 ng/mL, a meaningful jump accompanied by significant changes in luteinizing hormone (LH), the pituitary signal that tells the testes to produce testosterone. A separate trial comparing tadalafil and sildenafil found that both drugs increased total testosterone, but tadalafil produced a larger effect. Men on tadalafil also saw their LH levels drop, which suggests the body’s hormonal feedback system was responding to the higher testosterone by dialing back its production signal.
A 12-month study tracked testosterone, free testosterone, and estradiol in men taking tadalafil long term. Total testosterone nudged upward (from about 411 to 434 ng/dL) and free testosterone moved slightly higher as well, though neither change reached statistical significance on its own. What did change significantly was estradiol: it dropped from 19.9 to 16.6 ng/dL. That shift improved the testosterone-to-estradiol ratio from 26.3 to 32.6, meaning the hormonal balance tilted toward a more favorable profile even without a dramatic testosterone spike.
How Tadalafil Influences Hormone Balance
Tadalafil works by blocking an enzyme called PDE5, which breaks down a signaling molecule (cyclic GMP) that relaxes blood vessels. That’s the mechanism behind its effect on erections. But PDE5 inhibitors don’t interact with just one enzyme. Lab research on mouse Leydig cells, the testicular cells responsible for making testosterone, found that tadalafil also cross-interacts with PDE8A and PDE8B enzymes. These enzymes regulate a second signaling molecule (cyclic AMP) that plays a direct role in steroid production. When tadalafil interferes with those enzymes, it supports the intracellular signals that drive testosterone synthesis in response to LH stimulation.
The estradiol reduction seen in long-term studies points to another possible mechanism. Researchers have hypothesized that chronic tadalafil exposure may partially inhibit aromatase, the enzyme that converts testosterone into estrogen. Less conversion means more testosterone stays as testosterone, which would explain why the testosterone-to-estradiol ratio improves even when raw testosterone numbers don’t climb dramatically. A separate study found that daily tadalafil improved lean body mass in non-obese men, and the improvement correlated inversely with estradiol levels and positively with insulin sensitivity, both factors that support healthier testosterone production.
The Sexual Activity Feedback Loop
There’s a chicken-and-egg element to these findings. Sexual activity itself influences testosterone. Lack of sexual activity is associated with lower testosterone levels, and restoring regular sexual function can nudge testosterone upward. Tadalafil’s long half-life (it stays active in the body for up to 36 hours) gives it an edge here. In one comparative trial, men on tadalafil averaged 6.9 sexual encounters per month compared to 4.9 for those on sildenafil. That higher frequency of intercourse could independently contribute to the larger testosterone increases seen with tadalafil.
There may also be a direct brain-level effect. Nitric oxide, the molecule that tadalafil amplifies, stimulates gonadotropin-releasing hormone in the hypothalamus, the upstream signal that triggers the entire testosterone production chain. Whether the hormonal changes are driven more by restored sexual activity or by direct pharmacological effects on the brain and testes remains an open question. Both pathways likely contribute.
How This Compares to Actual Testosterone Therapy
The testosterone increases from tadalafil are real but modest. They tend to bring levels from the low-normal range into the mid-normal range, not from clinically low to high. For men with genuine testosterone deficiency (typically below 300 ng/dL), tadalafil alone is unlikely to be sufficient. The American Urological Association notes that men with both erectile dysfunction and testosterone deficiency should know that PDE5 inhibitors like tadalafil may work better when combined with testosterone therapy, suggesting the two treatments complement each other rather than substitute for one another.
The men who seem to benefit most from tadalafil’s hormonal effects are those with borderline-low testosterone, metabolic syndrome, or mild erectile issues where the hormonal shift from improved blood flow, reduced estradiol, and restored sexual activity can tip the balance. If your testosterone is solidly in the normal range, you’re unlikely to see a meaningful further increase. If it’s severely low, you’ll likely need direct hormone treatment.
What to Realistically Expect
Daily low-dose tadalafil (typically 5 mg) appears to offer a mild testosterone-supportive effect through several converging mechanisms: possible enhancement of Leydig cell signaling, reduced conversion of testosterone to estrogen, improved insulin sensitivity, increased lean mass, and a behavioral feedback loop from more frequent sexual activity. These effects build over weeks to months of consistent use, not overnight. The 12-month estradiol study showed progressive changes that accumulated over the full year.
The lean body mass improvements seen in one study reversed within two months of stopping tadalafil, suggesting that whatever metabolic and hormonal benefits the drug provides depend on continued use. This isn’t a permanent hormonal reset. It’s an ongoing physiological support that, for some men, creates a more favorable environment for natural testosterone production.