Since all tested imidazoles which suppress testosterone production have as a common feature a phenylated side chain of the imidazole molecule, this indicates a structure/activity relationship for the effects observed. In vitro studies with mouse Leydig cells demonstrated a direct reversible inhibition of testosterone biosynthesis by ketoconazole. Testosterone therapy suppresses sperm production, sometimes to zero, within months. This guide breaks down exactly when therapy helps, how it’s diagnosed, the safest treatments, and how to monitor results with confidence. In vivo perfusion of canine testes with ketoconazole inhibited the stimulation of testosterone production by human chorionic gonadotropin in a dose-dependent manner. Can ketoconazole shampoo be used to treat fungal infections on other parts of the body? Due to its efficacy at reducing systemic androgen levels, ketoconazole has been used with some success as a treatment for androgen-dependent prostate cancer. These findings indicate a delayed effect of ketoconazole on the synthesis of testosterone, although its blood levels are decreased to nearly zero. A single oral dose of 400 mg ketoconazole, a broad-spectrum antifungal drug, administered orally to 5 young men induced a drop in serum and saliva testosterone into the range of hypogonadism, while LH, FSH and prolactin levels remained unchanged. They can monitor for any potential side effects and ensure the continued effectiveness of the treatment, as well as discuss the potential for the ketoconazole shampoo to lower testosterone. Ketoconazole, an imidazole anti-fungal agent, has often produced features of androgen deficiency including decreased libido, gynecomastia, impotence, oligospermia, and decreased testosterone levels, in men being treated for chronic mycotic infections. Oral ketoconazole has been used clinically as a steroidogenesis inhibitor in men, women, and children at dosages of 200 to 1,200 mg/day. This effect is thought to be quite weak however, even with high oral doses of ketoconazole. It produces this effect through inhibition of 17α-hydroxylase and 17,20-lyase, which are involved in the synthesis and degradation of steroids, including the precursors of testosterone. As an antiandrogen, ketoconazole operates through at least two mechanisms of action. Resistance to ketoconazole has been observed in a number of clinical fungal isolates, including Candida albicans. Lower doses of fluconazole and itraconazole are required to kill fungi compared to ketoconazole, as they have been found to have a greater affinity for fungal cell membranes. Other uses include treatment of excessive male-patterned hair growth in women and Cushing's syndrome. Applied to the skin it is used for fungal skin infections such as tinea, cutaneous candidiasis, pityriasis versicolor, dandruff, and seborrheic dermatitis. In these patients the estradiol-testosterone ratio was persistently increased. The bound and free percentages of both hormones were not significantly altered. Ketoconazole, an antifungal drug, causes gynecomastia in some patients. It also inhibits androgen and glucocorticoid synthesis. Thus the link to other proteins binding androgens might be possible. 24 hours after treatment, however, the response of plasma testosterone to hCG was diminished. The diminution of testosterone synthesis could be significant as further therapeutic trials may use larger doses or more than once-daily administration. Most clinicians aim for mid‑normal total testosterone (often ~400–700 ng/dL), individualized to symptom control and side effects. For oral TU, plan regular blood pressure monitoring. The 2023 TRAVERSE trial in high‑risk men found testosterone was non‑inferior to placebo for major cardiac events over follow‑up, though there were slightly higher rates of atrial fibrillation, pulmonary embolism, and acute kidney injury. If you’re trying to conceive, avoid standard testosterone, it suppresses sperm production.
