Spironolactone

Spironolactone has two entirely separate jobs, and understanding both explains its side effects.

Job one — it's a diuretic (water pill). This is what it was invented for. It makes you get rid of extra salt and water, which is why it's used in heart failure. It's why you'll pee more, and why you may feel a bit dizzy or lightheaded, especially at first.

It's specifically potassium-sparing, meaning it holds onto potassium rather than flushing it out. That's the reason potassium levels get monitored.

Job two — it blocks androgens. This is why dermatologists use it, and it was originally a side effect rather than the point.

Androgens (male hormones like testosterone and DHT) tell your oil glands to produce more oil, and tell certain hair follicles to shrink. Spironolactone blocks the androgen receptor — the hormone is still there, but it can't dock and deliver its message. It also modestly reduces how much androgen your body makes.

The results:

• Less oil → fewer clogged pores → less acne
• Less DHT effect on hair follicles → slower thinning on the scalp
• Less androgen drive on facial hair → less unwanted hair growth

This is also why it works so well for hormonal acne specifically. It's not treating the pimple — it's turning down the hormonal signal that creates it.

For acne, doses typically run 50–200 mg daily, often starting at 50 mg and increasing if needed. Many women do well at 100 mg.

For hair loss, similar doses are used, often 100–200 mg.

Start low, go slow. Dermatologists usually start at 25–50 mg to let your body adjust, then increase. This reduces dizziness and other early side effects.

Timing. It makes you urinate more, so many people take it in the morning or early afternoon rather than at bedtime.

Be patient. Acne takes 6–12 weeks to improve meaningfully. Hair takes 6 months or more. A lot of people quit at week four thinking it isn't working. It usually is — it's just slow.

Blood tests. Potassium is checked before starting and sometimes after — though in healthy young women, dangerous potassium elevation is genuinely rare, and many dermatologists now do less frequent monitoring in this group. Older adults, people with kidney problems, and those on higher doses need closer checks.

It's ongoing treatment, not a course. Unlike isotretinoin, spironolactone controls acne while you take it. Stop, and hormonal acne typically returns. This is a long-term commitment.

Side effects are dose-dependent — they get more likely as the dose goes up.

At low doses (25–50 mg daily):

• Urinating more often. Expected — it's a water pill.
• Mild dizziness or lightheadedness, especially standing up quickly. Usually settles.
• Mild tiredness.
• Small potassium increases. Rarely significant at this dose.

At moderate doses (50–100 mg daily):

• Breast tenderness or slight swelling. One of the most common reasons people stop.
• Irregular periods or spotting.
• Higher potassium, more likely to warrant a blood test.

At high doses (100–200 mg daily):

• More noticeable breast tenderness and enlargement.
• More irregular periods.
• Larger potassium increases — monitoring matters more here.
• Low blood pressure, dizziness, or feeling faint on standing.

Other reported effects: headache, increased thirst, and reduced libido in some people.

Most of these are manageable, and many settle after the first few weeks. If breast tenderness or irregular periods are the issue, adding a combined oral contraceptive often helps with both — and it also provides the contraception you need anyway.

High potassium (hyperkalemia). The main serious risk. Very high potassium can cause dangerous heart rhythm problems. In healthy young women with normal kidneys, this is rare — the risk is much more relevant in older adults, people with kidney disease or heart failure, and those taking other medications that raise potassium.

Warning signs: muscle weakness, numbness or tingling, a slow or irregular heartbeat, or feeling unusually fatigued. Report these promptly.

Severe dizziness or fainting from low blood pressure.

Feminizing effects in men. Breast growth (gynecomastia) and breast tenderness. This is why spironolactone isn't generally used for acne in men — though it's used deliberately for this effect in gender-affirming care.

Kidney function changes. Monitored with blood tests.

A note on the old cancer warning. Spironolactone carries a historical warning about tumors, based on very high-dose rat studies. Large human studies have not shown an increased risk of breast or other cancers at the doses used in dermatology. It's a frequent source of anxiety, and the current evidence is reassuring — but it's a fair question to raise with your doctor.

Pregnancy: not recommended. Because spironolactone blocks androgens, there is a theoretical risk of interfering with the development of a male fetus's genitals. Human data is limited, but the concern is real enough that it's avoided.

Reliable contraception is required while taking it. This is a common reason a combined oral contraceptive is prescribed alongside — it handles the contraception and helps with the hormonal acne and the irregular periods.

If you become pregnant while taking it: stop and contact your doctor promptly. Don't panic — but do get advice quickly.

Breastfeeding: a small amount passes into breast milk. It's generally considered compatible with breastfeeding, but discuss it with your doctor.

Planning pregnancy: spironolactone clears your system quickly. Talk to your doctor about when to stop — usually well before trying to conceive.

Do not take if you have:

• High potassium (hyperkalemia)
• Significant kidney disease or kidney failure
• Addison's disease
• A known allergy to spironolactone
• Pregnancy, or plans to become pregnant

Use with caution / discuss with your doctor if you:

• Take ACE inhibitors or ARBs (lisinopril, losartan) — these also raise potassium
• Take potassium supplements or salt substitutes (many are potassium chloride)
• Take NSAIDs regularly (ibuprofen, naproxen) — can affect kidney function and potassium
• Have heart or liver disease
• Are an older adult
• Are a man seeking acne treatment — breast enlargement is likely, so other options are usually preferred

Worth flagging: salt substitutes marketed as "low sodium" are usually potassium-based. People add them for health reasons without realizing they interact with this medication.

How do I know if my acne is hormonal?
Hormonal acne typically appears along the jawline, chin, and lower cheeks — roughly the area where men grow a beard. It tends to flare around your period, and it's often deep, tender, and cystic rather than surface whiteheads. If that sounds like yours, spironolactone is likely to help.

How long until it works?
6–12 weeks for acne. Longer — 6 months or more — for hair. This is the single biggest reason people give up too early. Take before-and-after photos rather than relying on your memory.

Is 50 mg enough?
It can be for mild hormonal acne. Moderate to severe acne often needs 100–200 mg. Most dermatologists start lower and increase based on how you respond and tolerate it.

Does spironolactone cause weight gain?
No. It's a diuretic — if anything, it reduces water retention and bloating, so people often feel less puffy. It doesn't cause fat gain.

Does it change your body shape?
Not directly. It can reduce bloating and water retention, which changes how you look and feel. It can cause breast tenderness or slight breast enlargement, which some people notice.

Does it cause hair loss?
No — the opposite. It's used to treat hormonal hair loss by blocking the DHT that shrinks hair follicles.

Will it make me lose my period?
It can cause irregular periods, spotting, or missed periods, especially at higher doses. This is reversible when you stop. Adding a combined birth control pill usually regulates it — and covers contraception at the same time.

How much water should I drink?
Stay normally hydrated — around 8 cups a day. You don't need to drink extra to "flush it out," and drinking excessive amounts can throw off your electrolytes.

Can I use a salt substitute?
Be careful. Most "low sodium" salt substitutes are potassium chloride, and spironolactone already raises potassium. Check with your doctor.

Spironolactone or Accutane — which should I take?
Different tools for different problems.

Accutane shrinks oil glands and often produces permanent remission. It's a defined 4–6 month course, it's the strongest option for severe or cystic acne, and it comes with heavy monitoring and strict pregnancy prevention.

Spironolactone blocks hormones and works well for hormonal acne. It's simpler and gentler, with no iPLEDGE program — but it's ongoing treatment, not a cure. Stop it and hormonal acne typically returns.

For jawline acne that flares with your cycle, spironolactone is usually the better starting place. For severe, scarring, cystic acne, Accutane is the stronger answer.

Do natural alternatives work?
Spearmint tea has mild anti-androgen effects and small studies show modest benefit for hormonal acne. Green tea extract and cutting back on sugar and dairy may help some people. These are worth trying, but they are considerably weaker than spironolactone — sensible support, not a replacement, for moderate or severe acne.

Is the cancer warning on the label something to worry about?
That warning comes from studies using very high doses in rats. Large human studies have not found an increased cancer risk at the doses used in dermatology. Current evidence is reassuring, but bring it up with your doctor if it concerns you.