Anastrozole is a potent and selective non-steroidal aromatase inhibitor. In men, testosterone can be converted into estrogen by the enzyme aromatase. While some estrogen is necessary for male health, excessive levels (often a consequence of testosterone therapy or hormonal imbalances) can lead to undesirable side effects such as gynecomastia (breast tissue enlargement), water retention, and mood changes. Anastrozole helps to mitigate these risks by reducing this conversion, thereby helping to maintain an optimal testosterone-to-estrogen ratio.

Anastrozole works by inhibiting the enzyme aromatase, which is found in various tissues including fat, liver, and breast tissue. Aromatase is responsible for the final step in the biosynthesis of estrogens from androgen precursors (specifically, converting testosterone to estradiol and androstenedione to estrone). By blocking aromatase, anastrozole significantly reduces the amount of estrogen circulating in the bloodstream.

Anastrozole is taken orally, typically at a low dose when used for managing estrogen in men, with frequency varying from daily to a few times per week based on individual needs and hormone monitoring. Dosage adjustments are common and guided by blood tests measuring estrogen levels. Common side effects can include joint pain or stiffness, hot flashes, fatigue, headache, and mood disturbances. Long-term use, especially at higher doses, can potentially lead to decreased bone mineral density, so this should be monitored. It's crucial to use anastrozole only under the guidance of a healthcare provider who can carefully manage the dosage to avoid overly suppressing estrogen, as estrogen plays important roles in male health as well. Regular blood work is essential to ensure appropriate hormone balance.