Testosterone and Penis Size: How Much Can TRT Increase It?

Testosterone is one of the male sex hormones called androgens which play a significant role in regulating sexual health.

In fact, testosterone is the main factor stimulating the development of reproductive organs in boys and the formation of a penis even before birth.

Testosterone has the most significant effect on penile growth during puberty when T levels and dihydrotestosterone (DHT) reach their peak.

How testosterone increases penis size

Testosterone promotes penile formation and growth since the 8th week of intrauterine development. That’s the period when its production in the developing testicles begins.

At first, T production is stimulated by the placental human chorionic gonadotropin (hCG), while later, the hypothalamus and the pituitary gland take over by producing the gonadotropins – luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

In addition, the enzyme 5-alpha reductase found in peripheral tissue converts T into the more potent DHT, which also plays a significant role in penile growth. Also, as one of the side effects of over-the-counter testosterone usage, women’s clitoris after testosterone treatment can significantly enlarge from 14 mm to 46 mm.

After birth and before puberty, both androgen levels and penile growth remain low. Thus, the size of the penis increases only following whole-body development.

Yet, penile growth does not depend only on testosterone and dihydrotestosterone (DHT). Human growth hormone also influences the normal development of the reproductive system.

After the onset of puberty, androgen levels and penile growth reach their peak, and by the end of this period, the phallus reaches its final length and girth.

Although androgens can no longer stimulate penile growth after puberty, they do play a role in normal erectile function in adults. According to studies, testosterone has a complex effect on erections, and its presence even in extremely low levels is essential for the process.

Can testosterone therapy increase penis size in adults?

Once puberty is completed, penile tissues no longer respond to the growth stimuli by testosterone. Therefore, administering testosterone injections is not effective for penile growth if you are an adult man.

Nevertheless, testosterone therapy is highly effective in restoring average size in boys with micropenis as long as injections are taken before or during early puberty.

For example, one study has reported that testosterone injections increased the average stretched penile length from 15.54 to 37.18 mm in boys younger than 11 years old.

Research reports that topical and oral TRT (testosterone replacement therapy) is also effective in increasing penis size in children. In fact, there is no difference when comparing the benefits of topical to injectable testosterone for penis growth.

Even though TRT may help increase penis size in children, the final penile length of many patients treated for micropenis remains lower than average in adulthood.

Starting early treatment is usually the main factor that leads to better results in final penile length. Furthermore, TRT in childhood might not make your penis bigger beyond its genetically predetermined length and girth.

Evidence in adults with low T and hypogonadism does not report any benefits of testosterone injections for penis size in adults.

Currently, only one study in hypogonadal adults with micropenis has reported an increase in penis length after 6 months of TRT. However, this trial has a tiny sample size, and results are likely unreliable.

What is considered a micropenis?

Micropenis is a relatively rare congenital condition, which affects about 0.015% of all male newborns in the US.

The condition is defined as stretched penile length in newborns under 0.7 inches (2 cm). In adults, micropenis is considered as stretched penile length under 3.6 inches (9.1 cm).

The most common cause is abnormal hypothalamic or pituitary function. In such cases, the penis forms normally thanks to the stimulation of the testicles by maternal hCG. However, the process of penis growth stops after the 14th gestational week.

Can low T stop penile growth during puberty?

Since T levels and thus penile growth are at their peak during puberty, factors that affect testosterone production can have a negative effect on final penis size.

One such factor is childhood obesity. According to research, obese children have lower T levels and penile growth during puberty. The average penile length was 10% shorter than participants with normal body weight.

Yet, these effects occur only if obesity is present during puberty. Penile growth during the prepubertal period does not appear to be influenced by body weight and body fat levels.

How weight loss can make your penis bigger

Losing weight before puberty may be an excellent strategy to increase T levels and improve penile growth during this period of rapid growth.

Weight loss will also be beneficial for your T levels during adulthood if you are overweight or obese. Yet, it will not increase penis size in adults, apart from the purely visual effect of reduced prepubic fat on the penis.

Here’s how testosterone therapy can help you lose weight while increasing muscle mass and decreasing body fat percentage.

How can low T affect penis size in adulthood?

Furthermore, if you develop hypogonadism after the end of puberty, your penis size will likely remain unaffected. Therefore, penile atrophy or reduced penis size is not considered a symptom of hypogonadism.

Unfortunately, some forms of hypogonadism, such as those caused by pituitary problems, may affect the size of your testicles instead and lead to testicular atrophy.

Extremely low levels of testosterone and DHT, such as those achieved during androgen deprivation therapy for prostate cancer, may lead to penile shrinkage. In one trial, 15 months of androgen deprivation therapy reduced the mean stretched penile length from 10.76 cm to 8.05 cm.

Do penis enlargement products work?

The most commonly advertised options include pills, lotions, exercise techniques, and massages. However, these methods do not have any scientific evidence of safety or effectiveness in increasing the size of the penis.

Vacuum pumps are sometimes used to treat erectile dysfunction, but the enlargement effect is temporary and the procedure hides long-term risks.

Preliminary scientific results suggest that stretching via a penile traction device may lead to a small increase in penis size. However, the safety of the procedure is uncertain.

The only proven way to permanently enlarge your penis is to have surgery

Surgical interventions are recommended only when there is a medical condition such as micropenis. Micropenis in adults is defined as a length under 3 inches (7.5 cm).

However, the medical community does not endorse surgeries for purely cosmetic reasons. Such procedures are generally experimental and there is no guarantee of their safety or effectiveness.