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Spironolactone side effects and how to avoid them

Learn which side effects are common and when to see your healthcare provider
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By | Updated on Aug. 5, 2026 Medically reviewed by Leslie Greenberg, MD
Prescription pad with pill bottle: Spironolactone side effects, warnings and interactions

Key takeaways

  • Spironolactone’s most common side effect is hyperkalemia, which is a medical term meaning high blood potassium levels.

  • Spironolactone can also cause specific side effects in women, for example, menstrual irregularities, breast tenderness, and postmenopausal bleeding. 

  • Most side effects of spironolactone are mild, temporary, or reversible, and communicating with your healthcare provider can help you avoid or resolve side effects that may come up.

In this article:

Spironolactone is a commonly prescribed medication approved by the Food and Drug Administration (FDA) for conditions including heart failure, high blood pressure (hypertension), and fluid buildup (edema) due to liver cirrhosis or nephrotic syndrome. This versatile drug is also widely prescribed off-label (meaning not FDA-approved) in women for hormonal acne, female pattern hair loss, hirsutism, and polycystic ovary syndrome (PCOS), now called polyendocrine metabolic ovarian syndrome (PMOS). Because it works across multiple pathways, including fluid balance, electrolyte regulation, and hormone signaling, spironolactone comes with a distinct set of side effects worth understanding before starting treatment. 

Common side effects of spironolactone 

The most common side effects of spironolactone involve electrolyte imbalances, which can cause feelings of dizziness, lightheadedness, low blood pressure, headache, leg cramps, frequent urination, or worsening kidney issues. Other common side effects of spironolactone include:

  • Headache 
  • Breast pain and nipple pain 
  • High potassium levels in the blood
  • Digestive symptoms such as stomach pain, nausea, vomiting, cramping, diarrhea, and stomach bleeding
  • Decreased libido
  • Drowsiness
  • Irregular menstrual cycles 
  • Inability to achieve or maintain an erection
  • Mental confusion
  • Liver toxicity 

Many of these side effects are dose-dependent and may improve over time or with dose adjustments. If you experience new symptoms or worsening side effects after starting spironolactone or after an increase in dose, consult your healthcare provider for evaluation.

Serious side effects of spironolactone  

There is a risk of a few serious side effects when taking spironolactone. These include:

  • High blood potassium levels (hyperkalemia)
  • Low blood pressure
  • Worsening kidney function
  • Low blood sodium, magnesium, and calcium
  • Gynecomastia (growth of breast tissue in males)
  • Frequent urination
  • Abdominal pain

One way spironolactone works is by blocking the aldosterone receptor, which encourages elimination of sodium from the blood into the urine. As a result, potassium is kept in the blood, which can accumulate and cause side effects. Hyperkalemia can present as muscle weakness or paralysis; numbness, tingling, or burning sensations in the skin; or irregular heart rhythm. 

If left untreated, hyperkalemia can also result in a weak pulse, slow or irregular heartbeat, heart attack, colon blockage, or sudden collapse. This is why it’s important to know about other factors that can increase your risk of hyperkalemia, such as kidney disease, older age, and certain medications (discussed below). 

Spironolactone was found to be a tumor-causing agent in rat studies, which is why some of the drug’s labels carry a black box warning against unnecessary use; however, labels updated in 2026 have downgraded this information, as it is listed under toxicology rather than a black box warning. A review of studies published in 2022 found that spironolactone use in humans was not associated with an increased risk of breast or other solid organ cancers. 

Contact your healthcare provider immediately if you notice any signs of serious side effects while taking spironolactone.

Spironolactone side effects in females  

Spironolactone can contribute to a certain set of side effects in women, specifically because it can also bind to androgen and progesterone receptors. “Due to its anti-androgen effects, spironolactone causes side effects in females that may include breast tenderness and/or breast changes, and may also cause menstrual irregularities,” says Pankti Shah, Pharm.D., pharmacovigilance expert. Side effects that are more prominent in women include:

  • Menstrual irregularities (up to 30% of women), which include spotting between periods, heavier periods, or irregular cycles
  • Breast tenderness (about 17% of women) and breast enlargement
  • Sexual dysfunction, e.g., decreased libido and lubrication
  • Loss of monthly menstrual bleeding (amenorrhea) 
  • Postmenopausal bleeding

Spironolactone can be prescribed for acne and hirsutism in women because it can block androgen receptors. However, its action can also cause interference with regular hormonal cycling. Irregular cycles may be dose-dependent and are typically treated with oral contraceptives or an intrauterine device (IUD) to regulate them. Similarly, amenorrhea caused by spironolactone is reversed in a few months when patients stop the medication. “Post-menopausal females should seek medical attention for any unexplained post-menopausal vaginal bleeding,” adds Shah. 

Based on animal studies, spironolactone may feminize male fetuses and cause hormonal dysfunction in females. However, not enough research is available to determine the risk in human embryos and fetuses. Spironolactone is considered a Category C drug for pregnant people, meaning healthcare professionals may still prescribe spironolactone if they think the benefits outweigh the risks. Similarly, there isn’t enough data to guide whether spironolactone is unsafe for people while breastfeeding. 

Does spironolactone cause weight loss?  

“Spironolactone should not have a major impact on weight. It may have perceived weight loss benefits because of decreases in fluid retention with this medication,” says Christina Han, MD, board-certified dermatologist at False Creek Dermatology. Spironolactone works on high blood pressure and heart failure because of its diuretic effects, which cause excess fluid in the body to be removed through urine. Depending on the patient and drug, someone hospitalized with heart failure can lose an average of 6 kg (about 13 lbs) over 6 days while on diuretics. 

Diuresis can lead to patients feeling less bloated or having less swelling in their ankles because of the decreased water retention, but it’s not fat loss. Diuretics like spironolactone are not prescribed for weight management. Any sustained weight changes while taking spironolactone should be discussed with your healthcare provider.

How soon do spironolactone side effects start?  

Depending on your dose and how your body responds to the drug, spironolactone side effects can start within a few hours or a few days. It takes less than three hours for spironolactone to reach peak blood concentration. Spironolactone gets converted to canrenone, its active form, by the liver. Canrenone levels reach peak blood concentrations four hours after taking spironolactone. 

“Typically, side effects such as dizziness and light headiness will tend to occur early in the treatment course, and many of the more common side effects, if they occur, would be most notable within the first few weeks of treatment,” Dr. Han says. While symptoms of electrolyte imbalances may show up sooner, hormone-related side effects may take some time to develop. “Menstrual issues may occur within the first three months,” she adds. “Typically, these effects are temporary, but if they are severe or persist, definitely reach out to your prescriber,” she advises. 

In addition, liver injury can take about a month to show up on liver function blood tests.

How long do spironolactone side effects last?  

Most side effects of spironolactone are mild and may resolve on their own, while others may be dose-dependent, meaning adjusting the dose can often resolve side effects. The half-life of spironolactone is less than two hours, but its metabolites can stay in the body for up to 16.5 hours. 

Electrolyte-related side effects may resolve sooner with adjustments to dose, diet, medications, or hydration. Hormone-related side effects may take some time to resolve. For example, it can take up to two months for normal menstrual cycles to return after stopping spironolactone. In addition, one study found that women on spironolactone and oral contraceptives were less likely to have menstrual-related side effects than those just on spironolactone. 

Liver injury caused by spironolactone often resolves after patients stop the drug. 

“Dizziness and increased urination may resolve, but the persistence of breast tenderness and menstrual changes should be evaluated,” Shah says. If you experience worsening or prolonged side effects from taking spironolactone, talk to your healthcare provider for further evaluation, treatment adjustments, or to discuss alternative treatments. 

What are the long-term side effects of spironolactone?  

Long-term side effects from spironolactone are uncommon in healthy women, though healthcare providers may monitor kidney function, potassium levels, and liver enzymes during treatment. “Spironolactone is often well tolerated, but it is not a ‘set it and forget it’ medication. Patients should think of potassium, kidney function, and medication interactions as the three safety checkpoints,” Shah says. 

People with kidney problems or risk factors for hyperkalemia may increase the risk of long-term side effects, such as worsening kidney function. An eight-year study published in 2002 found no serious illnesses in women who used spironolactone for an average duration of about two years.

Spironolactone interactions 

The drug-drug interactions with the highest risks involve medications that also raise potassium levels, which include:

Spironolactone may also interact with lithium. Spironolactone can decrease the clearance of lithium, which means lithium may accumulate in the blood and cause lithium toxicity. People on both medications should have their lithium levels monitored closely. 

Review your medication list with your healthcare provider before taking spironolactone to discuss any possible interactions. 

How to avoid spironolactone side effects 

Most spironolactone side effects resolve with dose adjustments, time, or lifestyle changes. Taking spironolactone with food increases the drug’s bioavailability and reduces digestive upset. Avoid taking potassium supplements, salt substitutes containing potassium, or eating too much high-potassium foods such as bananas, orange juice, potatoes, or spinach.

“Stay hydrated as this medication is a diuretic,” Dr. Han says. “If you feel dizzy or lightheaded, consider adding some salt to increase fluid retention,” she adds. Shah also recommends slowly getting up from sitting or lying down to minimize dizziness, sticking to your prescribed dose of spironolactone, following up with your healthcare provider regularly, and doing a full medication review with your pharmacist or prescriber are other ways to avoid side effects. 

If you notice any changes in your menstrual cycle, seek medical advice from your healthcare provider early on so your treatment can be adjusted. 

Do not stop spironolactone without talking to your healthcare provider first. If the drug isn’t a good fit, discuss with your provider about alternatives to spironolactone. “If you’re not sure about a potential side effect, always consult a health care professional,” Dr. Han says.

Frequently asked questions  

Does spironolactone cause weight gain?

Weight gain is not listed as a side effect of spironolactone. 

What should you avoid while taking spironolactone?

You should avoid taking medications, supplements, or eating foods that increase your risk of hyperkalemia. 

What’s the most common side effect of spironolactone?

The most common side effect of spironolactone is high blood potassium levels, also called hyperkalemia. 

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