Spironolactone typically requires 100 to 200 mg per day to meaningfully block testosterone’s effects, with doses up to 400 mg used in some cases. The exact amount depends on why you’re taking it: gender-affirming hormone therapy, hormonal acne, or excess hair growth from conditions like PCOS each call for different ranges and goals.
How Spironolactone Blocks Testosterone
Spironolactone was originally designed as a blood pressure medication that blocks aldosterone, a hormone involved in fluid balance. But it also binds to androgen receptors, the docking sites where testosterone and its more potent form (DHT) normally attach to trigger their effects. By occupying those receptors, spironolactone prevents testosterone from doing its job in tissues like skin, hair follicles, and oil glands. It’s roughly 20 times weaker than DHT at binding to these receptors, which is why relatively high doses are needed to produce a meaningful anti-androgen effect.
Spironolactone also appears to interfere with testosterone production itself, not just its activity at the receptor level. It does not, however, block the enzyme that converts testosterone into DHT. This dual action, reducing both the production and the tissue-level activity of androgens, is what makes it useful across several conditions.
Doses for Gender-Affirming Hormone Therapy
In feminizing hormone therapy, the standard spironolactone dose is 100 to 200 mg per day, taken in divided doses. Some prescribers go as high as 300 or even 400 mg daily when lower doses aren’t achieving adequate suppression. The clinical goal is to bring serum testosterone into the typical female range of 30 to 100 ng/dL, down from a starting point that’s often 300 to 1,000 ng/dL or higher.
Spironolactone is almost always prescribed alongside estrogen in this context, and the combination matters. Estrogen independently suppresses testosterone production through the body’s hormonal feedback loop, so the two medications work together. This synergistic effect means a person taking both estrogen and spironolactone may need a lower spironolactone dose than someone taking it alone. Most clinicians start at 100 mg daily and adjust based on lab results, checking testosterone and estradiol levels at follow-up visits to see whether the target range has been reached.
Reaching that 30 to 100 ng/dL target can take several months of dose adjustment. Bloodwork is typically checked every few months early on, then less frequently once levels stabilize. If testosterone remains stubbornly high at 200 mg, a prescriber may increase the dose or consider switching to or adding a different anti-androgen.
Doses for Acne and Excess Hair Growth
For hormonal acne and hirsutism (excess body or facial hair), the recommended range is also 100 to 200 mg per day, split into two doses. These conditions are driven by androgen activity in the skin rather than by high testosterone blood levels overall, so the goal is slightly different. You’re blocking testosterone at the tissue level rather than trying to push blood levels into a specific range.
At 100 mg daily, many people see improvement in hormonal acne within two to three months. Hirsutism takes longer. In a 12-month study of patients taking 200 mg daily, hirsutism scores dropped significantly, though testosterone blood levels themselves didn’t always change. This reinforces that spironolactone’s main benefit in these conditions comes from blocking androgen receptors in the skin, not from lowering circulating testosterone.
Dermatologists sometimes start as low as 25 to 50 mg for mild hormonal acne and increase if needed. For more severe androgen-driven symptoms, 150 to 200 mg is common. These doses are typically combined with an oral contraceptive, which provides additional androgen suppression and prevents the menstrual irregularity spironolactone can cause.
Why the Dose Varies So Much
Several factors influence how much spironolactone a given person needs. Body weight plays a role, since a larger body distributes the drug across more tissue. Baseline testosterone levels matter too: someone starting with testosterone at 600 ng/dL will need more aggressive treatment than someone at 350 ng/dL. Whether you’re taking estrogen or an oral contraceptive alongside it makes a significant difference because of the synergistic suppression effect.
Individual variation in how quickly your liver processes the drug also affects its potency. Spironolactone is converted into several active metabolites, and the speed of that conversion differs from person to person. This is one reason prescribers rely on bloodwork rather than a fixed dose: two people taking the same amount can end up with very different testosterone levels.
Potassium and Other Side Effects
Because spironolactone is a potassium-sparing diuretic, it causes your kidneys to retain potassium instead of excreting it. At the doses used for testosterone blocking (100 to 400 mg), the risk of elevated potassium is real and needs monitoring. Potassium levels should be checked before starting the medication, then again within the first week or two. After that, periodic checks continue, ranging from every few months to a couple of times a year depending on your risk profile.
People most vulnerable to dangerously high potassium include those with diabetes, kidney problems, or anyone taking other medications that raise potassium levels, such as certain blood pressure drugs or anti-inflammatory painkillers like ibuprofen. If you fall into one of these categories, closer monitoring is essential. You should also avoid potassium supplements and salt substitutes (which are potassium-based) while on spironolactone, and let your prescriber know if you experience prolonged vomiting or diarrhea, since dehydration can concentrate potassium in the blood.
Other common side effects include increased urination (especially in the first few weeks), breast tenderness, lightheadedness from lower blood pressure, and irregular periods in people who menstruate. These tend to be more pronounced at higher doses and often settle down over time.
How Long Until It Works
Lab changes in testosterone levels can show up within weeks, but the physical changes people care about take much longer. For acne, most people notice improvement within two to three months. Reduced hair growth in hirsutism typically takes six to twelve months to become clearly visible, since hair follicles operate on long growth cycles. In feminizing hormone therapy, softening of skin and redistribution of body fat may begin within the first few months, but the full range of changes unfolds over one to three years.
Because the timeline is slow, it’s important not to increase the dose prematurely. Clinicians generally wait at least three months before adjusting, using lab results rather than visible changes to guide dosing decisions in the early stages.