What is an aromatase inhibitor?
Aromatase inhibitors are medications that block the enzyme aromatase, preventing the conversion of testosterone to estrogen in the body, commonly used as an ancillary treatment during testosterone replacement therapy.
An aromatase inhibitor is a class of medication that stops the enzyme aromatase from converting testosterone into estrogen. Common examples include anastrozole, letrozole, and exemestane. In the context of testosterone replacement therapy, these drugs are prescribed as ancillary medications rather than primary treatments, serving to manage estrogen-related side effects that can emerge during TRT.
When testosterone levels rise through replacement therapy, a portion naturally converts to estrogen through aromatase activity. Without intervention, this can lead to side effects like gynecomastia (breast tissue growth), water retention, and mood swings. An aromatase inhibitor moderates estrogen levels by blocking this conversion pathway, helping maintain a more favorable hormone balance during treatment.
Aromatase inhibitors are not first-line TRT medications. Instead, they are prescribed selectively by clinicians when an individual shows signs of excess estrogen or has a personal or family history of conditions sensitive to estrogen levels. Dosing and duration depend on individual response and lab work. Providers at hormone therapy clinics monitor patients regularly to adjust ancillary medications as needed, since overuse of aromatase inhibitors can suppress estrogen below healthy levels, which carries its own risks.