Spironolactone is off-limits for anyone with high potassium levels, Addison’s disease, or who is already taking eplerenone (a closely related medication). Beyond those absolute contraindications, several other groups face serious risks that often make spironolactone a poor choice, including people with significant kidney disease, pregnant women, and those on certain blood pressure medications.
Absolute Contraindications
The FDA lists three situations where spironolactone should not be used at all. The first is hyperkalemia, meaning your blood potassium is already elevated. Spironolactone works by blocking a hormone called aldosterone, which normally tells your kidneys to flush out potassium. When that signal is blocked, potassium builds up. If your levels are already high, the drug can push them into a dangerous range that disrupts heart rhythm.
The second is Addison’s disease, a condition where the adrenal glands don’t produce enough hormones, including aldosterone. Since people with Addison’s already struggle to regulate potassium, adding a drug that raises it further is dangerous. The third is taking eplerenone, which works on the same receptor. Combining the two compounds the potassium-raising effect.
Kidney Disease and Reduced Kidney Function
Your kidneys are the main route for clearing excess potassium from the body, so when they aren’t working well, spironolactone’s potassium-raising effect becomes much harder to manage safely. Clinical guidelines generally require an eGFR above 30 (a measure of how efficiently your kidneys filter blood) and a potassium level below 5.0 mEq/L before starting the drug. Heart failure guidelines also caution against use when serum creatinine exceeds 2.5 mg/dL.
People who produce little or no urine, such as those with end-stage kidney disease, face an even steeper risk. Without adequate urine output, the body has almost no way to get rid of the extra potassium spironolactone causes to accumulate. While some research has explored spironolactone in dialysis patients under close supervision, current guidelines treat significant kidney disease as a contraindication.
Dangerous Drug Combinations
Spironolactone combined with ACE inhibitors or angiotensin receptor blockers (ARBs), two of the most commonly prescribed blood pressure medications, can cause life-threatening hyperkalemia. Both drug classes independently reduce potassium excretion through the kidneys. Together with spironolactone, the effect stacks. A case series published in the BMJ documented that this combination led to severe hyperkalemia, dangerous heart rhythms, and deaths, particularly in patients who also had reduced kidney function.
Other combinations to avoid include potassium supplements, other potassium-sparing diuretics like amiloride or triamterene, and even potassium-based salt substitutes. Lithium is another concern: spironolactone slows lithium clearance, which can push lithium to toxic levels. If you’re on any of these medications, your doctor needs to weigh the risks carefully or choose a different approach.
Older Adults
Age is one of the strongest risk factors for spironolactone-related hyperkalemia. The American Geriatrics Society’s Beers Criteria, which flags medications that are potentially inappropriate for older adults, lists spironolactone as one to avoid due to hyperkalemia risk, with a strong recommendation backed by moderate-quality evidence. The reason is straightforward: kidney function naturally declines with age, often more than standard blood tests reveal. In elderly patients, especially those who are thin or have low muscle mass, a normal-looking creatinine level can mask significantly reduced kidney filtration. That hidden decline makes potassium buildup more likely and harder to predict. The risk climbs further when spironolactone is paired with an ACE inhibitor or ARB, a combination that is common in older adults managing heart failure or high blood pressure.
Pregnancy and Breastfeeding
Spironolactone should be avoided during pregnancy. Animal studies have shown that the drug can cause feminization of male offspring, meaning a male fetus may develop female physical characteristics. This happens because spironolactone blocks androgen (male hormone) receptors, and a developing fetus is especially sensitive to hormonal disruption.
Human data is limited. There are case reports of women who took spironolactone during pregnancy and delivered babies without obvious birth defects, but the evidence is too thin to consider it safe. Whether spironolactone increases the risk of preterm delivery or low birth weight is also unknown. The drug does pass into breast milk in small amounts, though the levels are generally considered too low to affect most nursing infants.
Women With Breast Cancer Risk
Because spironolactone has anti-androgen properties, it’s widely prescribed off-label for hormonal acne in women. But dermatology guidelines recommend avoiding it in women who have a personal history of breast cancer or estrogen-related tumors. A family history of breast cancer, particularly in a first-degree relative, is also reason for caution. The concern is that spironolactone’s hormonal activity could theoretically promote tumor growth in susceptible individuals. If you’re considering spironolactone for acne or hair loss, this is something to discuss before starting.
What Monitoring Looks Like
Even for people who can safely take spironolactone, potassium monitoring is essential. Prescribing guidelines recommend checking potassium within one week of starting the medication, and heart failure and hypertension guidelines suggest monitoring within one to four weeks. After that, periodic checks continue for as long as you take the drug, with more frequent testing if you have any additional risk factors like older age, mild kidney impairment, or concurrent use of other medications that affect potassium.
Sodium levels also need watching. Spironolactone can lower sodium, and in patients with liver cirrhosis (where the drug is commonly used to treat fluid buildup), guidelines call for stopping diuretics entirely if sodium drops to 120 mEq/L or below. Even moderately low sodium with rising creatinine is a signal to pause the medication and reassess.