Exogenous testosterone therapy is used by transgender men and non-binary individuals to induce physical changes that align with their gender identity. This gender-affirming hormone therapy (GAHT) involves administering testosterone to achieve circulating levels typical of the male range. The systemic shift affects numerous body systems, including the vocal cords, muscle mass, and fat distribution. Localized changes occur in the vulvovaginal tissues, which respond directly to increased androgen levels and decreased estrogen. This article focuses on the anatomical and physiological shifts in the external and internal genital structures that occur while on testosterone.
Changes to External Genitalia and Sensation
The most consistent alteration to the external genitalia is the growth of the clitoris, commonly referred to as “bottom growth” or clitoral hypertrophy. This change is driven by androgen receptors in the clitoris’s erectile tissue, which shares embryological origins with the penis. Testosterone, and its more potent derivative dihydrotestosterone (DHT), stimulate the growth and enlargement of this tissue, often resulting in an increase in both length and circumference.
The extent of this growth is highly variable, but an increase of 1 to 4 centimeters is frequently observed, with most changes occurring in the first year of treatment. The labia minora may also shrink or thin in response to the hormonal environment. This external shift can lead to altered sensation, including hypersensitivity, particularly during the initial months of therapy. Some people experience a change in the quality of orgasm, which may become more intense or abrupt, and can sometimes be accompanied by discomfort or a tingling sensation.
Internal Anatomical Shifts and Atrophy
The primary effect of high-dose exogenous testosterone on the internal reproductive tract is the suppression of ovarian estrogen production, creating a hypoestrogenic state similar to that experienced during menopause. Since the lining of the vaginal canal and the cervix are highly dependent on estrogen for health, this lack of hormone causes the tissue to thin and lose elasticity, a condition known as vaginal atrophy. The epithelial layers of the vaginal wall shrink, leading to a depleted state where the tissue becomes fragile and more prone to irritation.
Vaginal atrophy can manifest as symptoms including chronic dryness, itching, burning, and micro-tearing or bleeding, especially during sexual activity. Painful intercourse, or dyspareunia, is reported to be high among individuals on testosterone, reaching up to 60% in some studies. The change in the vaginal lining also disrupts the natural ecosystem, altering the vaginal microbiome. Specifically, the population of protective Lactobacillus bacteria decreases, which results in a rise in the vaginal pH and an increased susceptibility to infections like Bacterial Vaginosis (BV) and urinary tract infections (UTIs).
Clinical Management of Tissue Health
Managing the symptoms of vaginal atrophy is a practical necessity for maintaining comfort and tissue integrity, and localized treatments are highly effective. The most common and recommended treatment involves the use of low-dose topical estrogen, which is available in creams, rings, or vaginal tablets. These products are absorbed directly by the vaginal tissue to restore its thickness and elasticity, reversing the atrophic changes. Importantly, the dosage of estrogen used in these localized treatments is so low that it typically does not result in significant systemic absorption, meaning it does not interfere with the masculinizing effects of the systemic testosterone therapy.
Alongside hormone treatment, non-hormonal strategies include the regular use of vaginal moisturizers and lubricants. Moisturizers help to hydrate the tissue for long-term relief, while lubricants reduce friction during sexual activity, minimizing the risk of micro-tears and irritation. Regular medical check-ups, including pelvic exams and Pap smears, remain an ongoing necessity for individuals with a cervix, but atrophy can make these examinations physically uncomfortable. In cases of severe atrophy, a healthcare provider may prescribe a course of topical estrogen for several weeks prior to an attempted exam to improve tissue health and increase comfort.
Pre-Surgical Considerations for Bottom Surgery
For individuals planning gender-affirming bottom surgery, the anatomical changes induced by testosterone play a significant role in surgical preparation and outcomes. The growth of the clitoris, or hypertrophy, is a desirable effect for procedures such as metoidioplasty, where the existing genital tissue is used to construct a small phallus. Surgeons may recommend a period of testosterone use, sometimes one to two years, to maximize this growth before the procedure is performed.
The health and quality of the internal vaginal tissue are also relevant, particularly if a vaginectomy—the surgical removal of the vaginal canal—is planned as part of a phalloplasty or metoidioplasty. While atrophy can be present, maintaining the health of the surrounding tissue is still important to minimize the risk of post-operative complications. Furthermore, certain procedures, like phalloplasty, require pre-operative hair removal in the planned surgical site, which is an important step in preventing complications like hair growth within the newly created urethra. Continuing testosterone therapy is generally considered safe during the perioperative period for most surgeries, as evidence does not suggest a routine need for discontinuation.