Spironolactone for PCOS (Now PMOS): How Long It Takes to Work — and What Happens If You Stop

You leave the appointment with a prescription for spironolactone, a dose that will probably go up in a month, and one sentence of explanation: give it time. How much time? For which symptom? And what happens if you eventually want to come off it?

Those are the three questions people actually type into a search bar, and the ones most explainers skip. This page answers them with what the evidence says — including the parts less flattering than the marketing.

PCOS is now PMOS — Polyendocrine Metabolic Ovarian Syndrome, renamed by international consensus in May 2026. Both names are still in use, so both appear here. Nothing below is medical advice; dose and suitability are decisions for you and your clinician.

What spironolactone actually does — and what it doesn't touch

Spironolactone started life as a potassium-sparing diuretic for blood pressure and heart failure. Its use in PCOS is a repurposing: at the doses used here it blocks androgen receptors, so testosterone and its more potent relative DHT have a harder time reaching the tissue that responds to them — hair follicles and oil glands. That mechanism defines the whole map of what it can and can't do.

It targets androgen-driven skin and hair symptoms: unwanted hair growth (hirsutism), androgen-pattern acne along the jaw and chin, and scalp thinning at the crown and part.

It does not treat the metabolic side of PMOS. Insulin resistance — the hub that drives much of the syndrome — is untouched by receptor blockade. Neither is weight. If the scale drops in the first couple of weeks, that's the diuretic effect moving fluid, not a change in body composition.

And here is the part the operator pages tend to leave out. The systematic review and meta-analysis that fed the 2023 International Guideline found anti-androgens plus lifestyle beat metformin plus lifestyle for hirsutism — but did not significantly beat placebo plus lifestyle for the same outcome, across the trials available. Most of the confidence in spironolactone comes from hirsutism trials in mixed populations rather than large PCOS-specific ones, and a Cochrane review rated that evidence low quality even where it was positive. It is a reasonable, widely used drug. It is not the settled slam dunk a sales page implies.

The realistic timeline, symptom by symptom

Spironolactone doesn't shrink a hair or clear a pore that already exists. It changes what grows next — so every timeline below is set by the biology of the follicle, not the drug.

• Acne: roughly 3 to 6 months. The fastest-responding symptom, because the oil-gland turnover it depends on is quick. Some people notice a shift by month two or three; judging it before month three is premature.
• Hirsutism: 6 months minimum, up to 12–18 for the full picture. A terminal hair follicle runs a growth cycle measured in months. You are waiting for the next cycle to come in finer, so nothing visible happens until enough follicles have turned over.
• Scalp thinning: the slowest, 12 months and beyond. Scalp follicles have the longest growth phase of the three. Regrowth, where it happens, is measured across a year, not a season.

Two practical notes. The 2023 International Evidence-based Guideline treats six months as the minimum trial before judging an anti-androgen's effect — which means a "this isn't working" verdict at week eight is judging the follicle cycle, not the drug. And the same meta-analysis found daily dosing clearly outperformed dosing every three days for hirsutism, so consistency does real work here.

One durable caveat worth knowing up front: hirsutism treatment is far better at preventing new coarse hair than at reversing follicles that have already converted. Anti-androgens hold the line; they don't rewind it. Cosmetic hair removal and drug therapy are complements, not alternatives.

Spironolactone or the pill? What the guideline actually recommends

This is usually framed as a choice between two options. In the guideline, it isn't one.

The 2023 International Evidence-based Guideline recommends combined oral contraceptives as first-line in adults with PMOS for irregular cycles or hirsutism, with low-dose preparations preferred for hirsutism. Anti-androgens like spironolactone come in as a second step: they could be considered, in combination with effective contraception, where there has been a suboptimal response after a minimum of six months of the pill and/or cosmetic therapy.

So the real-world sequence for most people is the pill first, spironolactone added if six months of it hasn't done enough — which is why so many prescriptions are for the two together rather than one instead of the other. They work on different points of the same pathway: the pill lowers circulating androgens and raises SHBG so less is free, while spironolactone blocks what's left from binding. Spironolactone moves to the front of the queue mainly when combined contraceptives are contraindicated or not tolerated — and even then, the contraception requirement below still applies.

The side effects that actually show up

Most people tolerate spironolactone. But the honest list is more specific than "generally well tolerated."

• Breakthrough bleeding is the common one. In a Padova cohort of 63 women treated for hyperandrogenic skin symptoms, intermenstrual bleeding occurred in 68.2% — the most frequent side effect by a wide margin, and concentrated in the classic PMOS phenotype. It's the reason a lot of people quit, and it's often manageable with a dose or regimen change rather than stopping outright.
• High potassium is real but uncommon in the typical patient. Spironolactone is potassium-sparing. In healthy women under 45 with normal kidney function the risk is low; monitoring matters more with age, reduced kidney function, or concurrent ACE inhibitors, ARBs, NSAIDs, or potassium supplements. Whether you need periodic bloods is a question for your prescriber, not a rule you can read off a webpage.
• Dizziness or lightheadedness, especially early or on a dose increase, from the mild blood-pressure effect. Breast tenderness also occurs.
• Effective contraception is required, not optional. Spironolactone crosses the placenta and can interfere with the development of a male fetus. This is the single non-negotiable of the drug, and it's why the guideline pairs anti-androgens with contraception in the recommendation itself.

What happens when you stop — the question nobody answers

Nearly every page on spironolactone stops at "keep taking it." The most useful evidence is about what happens after.

The Padova group followed those 63 women with PMOS-related skin symptoms, treated with spironolactone as first-line therapy for a mean of about 26 months, and then tracked them after they came off it. The split was striking: 38 still had lasting benefit an average of roughly 34 months after withdrawal, while 20 relapsed at an average of about 17.5 months. Phenotype mattered — women with the ovulatory PMOS pattern had been treated for less time and tended to relapse sooner.

Read that carefully, because it cuts two ways.

The encouraging read: for a majority here, the benefit outlasted the prescription by years. Spironolactone is not automatically a forever drug, and the common fear that everything snaps back the month you stop wasn't what happened to most of them.

The sober read: this was a retrospective, single-center study with no control group, and the researchers found no measurement that predicted which group anyone landed in. No test tells you in advance whether you're a 34-month person or a 17-month person — and a meaningful minority did relapse.

The practical takeaway is that stopping is a planned conversation with a defined follow-up window, not a decision to make silently — and that longer treatment before stopping, as the ovulatory-phenotype finding hints, may be part of what buys durability.

How to tell whether it's working for you

Because the timelines are long and the change is gradual, memory is a bad instrument. Two things make the six-month judgment call honest: photograph a fixed area — same jawline, same part line, same lighting — at the start and monthly, since month-to-month change is invisible but month-one-to-month-six is not; and track the symptom, not the mood, counting coarse hairs removed weekly or active lesions rather than a general sense of whether things feel better.

If six months at a stable dose produces nothing, that's meaningful information — and usually a prompt to revisit the driver rather than the drug. Androgen-blocking does nothing for a symptom actually driven by thyroid disease, iron deficiency, or unaddressed insulin resistance. Our guides on PMOS acne versus other adult acne and PMOS hair loss versus androgenic alopecia walk through how to tell those apart.

If you want a structured read on which driver looks dominant in your own pattern — before spending six months on a treatment aimed at the wrong one — you can work through Oestra's assessment, and it's worth understanding which type of PMOS your picture fits, since the Padova data suggests phenotype shapes how this drug behaves long-term.

Spironolactone is a slow, unglamorous, mostly well-tolerated tool that works on one specific part of PMOS. Knowing which part — and how long to give it before you judge — separates a fair trial from a wasted year.

Sources

• Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 International Evidence-Based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Monash University; endorsed by ESHRE and ASRM, 2023. — The source for combined oral contraceptives as first-line for hirsutism and irregular cycles in adults; for anti-androgens being considered, with effective contraception, after a suboptimal response to a minimum of six months of COCP and/or cosmetic therapy; and for the six-month minimum trial period.
• Alesi S, Forslund M, Melin J, et al. Efficacy and safety of anti-androgens in the management of polycystic ovary syndrome: a systematic review and meta-analysis of randomised controlled trials. EClinicalMedicine. 2023;63:102162. PMID: 37583655. — The meta-analysis conducted to inform the 2023 guideline. Source for anti-androgens plus lifestyle being superior to metformin plus lifestyle for hirsutism, but not significantly superior to placebo plus lifestyle; and for daily dosing outperforming dosing every three days.
• Sabbadin C, Beggiao F, Keiko Vedolin C, et al. Long-Lasting Effects of Spironolactone after its Withdrawal in Patients with Hyperandrogenic Skin Disorders. Endocr Metab Immune Disord Drug Targets. 2023;23(2):188–195. PMID: 35532249. — The withdrawal cohort: 63 women with PCOS-related hyperandrogenic skin symptoms, mean treatment 25.7 months; 38 with prolonged effect at a mean 33.7 months post-withdrawal versus 20 relapsing at a mean 17.5 months; intermenstrual bleeding in 68.2%; earlier relapse in the ovulatory phenotype. Retrospective and uncontrolled.
• van Zuuren EJ, Fedorowicz Z, Carter B, Pandis N. Interventions for hirsutism (excluding laser and photoepilation therapy alone). Cochrane Database of Systematic Reviews. 2015;(4):CD010334. PMID: 25918921. — Source for spironolactone 100 mg daily being more effective than placebo in reducing Ferriman–Gallwey scores (mean difference −7.69, 95% CI −10.12 to −5.26), on evidence the review graded as low quality.

A note on scope: spironolactone's mechanism as an androgen-receptor blocker, and the follicle-cycle biology that sets the timelines above, are well-established general clinical facts rather than findings from any single study. The specific figures cited — timelines, percentages, and effect sizes — come from the sources listed.