Spironolactone: Uses, Dosage, Side Effects, Safety

Spironolactone is a potassium-sparing diuretic and anti-androgen used for several conditions. You’ll see it prescribed for heart failure, resistant hypertension, fluid retention (edema), primary hyperaldosteronism, and off-label for acne or hair loss linked to hormones. It helps the body remove excess salt and water while keeping potassium, and it blocks androgen receptors which reduces oil production and hair thinning in some people.

How it’s used and dosing

Typical starting doses vary by condition. For heart failure or edema adults often start at 12.5–25 mg once daily and may increase to 50–100 mg daily as needed. For resistant hypertension doses commonly reach 25–50 mg daily. For hormonal acne in adults, doctors often use 50–100 mg daily, sometimes split into two doses. Kidney function and potassium levels shape the dose. Older adults usually start lower. Never change dose without talking to your prescriber.

What to watch for & monitoring

The main risk is high potassium (hyperkalemia). Symptoms include weakness, tingling, palpitations, or sudden heartbeat changes. People with reduced kidney function, those taking ACE inhibitors, ARBs, NSAIDs, or potassium supplements have higher risk. Your doctor will check blood potassium and creatinine within a week or two of starting, and periodically after. Stop and contact your provider if you get lightheaded, faint, or notice muscle weakness.

Common side effects are breast tenderness, breast enlargement in men (gynecomastia), menstrual changes, fatigue, dizziness, and increased urination. Some of these effects improve over time; gynecomastia can persist. If you are pregnant or plan to become pregnant, avoid spironolactone because anti-androgen effects can harm a developing male fetus. Breastfeeding advice varies—talk to your clinician.

Drug interactions & precautions Don’t combine spironolactone with other potassium-sparing drugs, potassium supplements, or salt substitutes that add potassium. Using it with ACE inhibitors or ARBs raises hyperkalemia risk. NSAIDs can reduce kidney blood flow and worsen kidney-related side effects. Be cautious with lithium and some heart rhythm medicines. Always give a full medicine list to your clinician.

Practical tips Keep a routine for taking it—same time each day helps. If you miss a dose, skip it and take the next scheduled one. Limit high-potassium foods only if your doctor tells you to; many patients do fine without strict restriction. If you have signs of dehydration or a severe infection, call your provider because dose adjustments may be needed.

Questions to ask your prescriber How often will my potassium be checked? What dose do you recommend for my condition? Are there safer alternatives given my other medicines? How long will I need spironolactone?

This guide gives practical points to discuss with your clinician. Spironolactone can be helpful when used with the right monitoring.

Expect blood tests at baseline, within one to two weeks after starting, then monthly until stable, and every three months after that unless problems occur. If potassium rises above 5.5 mmol/L or creatinine increases significantly, your doctor will stop or lower the dose. Eplerenone is a similar drug with fewer sex-hormone effects and higher cost.