Does Spironolactone Cause Weight Gain? What Official Drug Guides List
Medically reviewed by Dr. Michael Teplitsky, MD Last reviewed 2026-10-04
Official drug information from the NHS and MedlinePlus does not list weight gain as a side effect
Neither the NHS nor MedlinePlus lists weight gain as an established side effect of spironolactone. The medicine is prescribed for swelling from fluid build-up, high blood pressure, and heart failure, with common side effects such as nausea, dizziness, and breast pain. Anyone experiencing unexpected weight changes while taking spironolactone should consult their prescribing doctor.
Neither the NHS nor MedlinePlus lists weight gain among the recorded side effects of spironolactone. At The Metabolic Journal, we summarize what the NHS and MedlinePlus report on this medicine. The absence of weight gain on these official drug reference pages does not prove that body weight cannot change during treatment, and these pages are not a complete record of every possible reaction.
Spironolactone is prescribed to treat swelling caused by fluid build-up, and physicians also use it for conditions including high blood pressure, heart failure, hyperaldosteronism, and low potassium. Because body weight can shift for many different reasons, you should discuss any unexpected weight changes directly with your prescriber rather than making assumptions about the cause.
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Official drug guidance from the NHS and MedlinePlus does not include weight gain on its list of spironolactone side effects. The NHS reports that spironolactone is a medicine used to treat swelling caused by fluid build-up, as well as high blood pressure and heart failure. MedlinePlus notes that the medicine is prescribed to treat hyperaldosteronism, low potassium, heart failure, and edema, and can be taken alone or with other medications for high blood pressure.
Documented side effects focus primarily on other symptoms. Common side effects identified by the NHS include feeling dizzy, feeling sick (nausea), muscle or leg cramps, feeling tired or low in energy, and breast pain or increased breast size, including in men. MedlinePlus similarly documents enlarged or painful breasts and irregular menstrual periods as known side effects.
Side Effects and Serious Warning Signs
The documented side effects of spironolactone range from mild daily symptoms to serious warning signs that require contact with a doctor. The NHS notes that spironolactone will not usually affect driving or using machinery, but you should wait until symptoms resolve if you feel dizzy or experience vision problems after taking your dose.
| Category | Reported Symptoms | Guidance |
|---|---|---|
| Common side effects | Feeling dizzy, nausea, muscle or leg cramps, feeling tired or low in energy, breast pain, increased breast size, irregular menstrual periods | Wait for dizziness or vision problems to stop before driving or operating machinery |
| Warning signs | Muscle weakness, pain, or cramps; pain, burning, numbness, or tingling in hands or feet; changes in heartbeat; confusion; nausea; extreme tiredness; dry mouth, thirst, dizziness; unusual bleeding or bruising; yellowing of skin or eyes; difficulty breathing or swallowing; vomiting blood; blood in stools; decreased urination; fainting | Call a doctor promptly for medical evaluation |
MedlinePlus also highlights that spironolactone has caused tumors in laboratory animals. Patients should discuss the risks and benefits of the medication with their doctor.
Dietary Precautions and Potassium Levels
Spironolactone can sometimes raise potassium levels and cause hyperkalaemia, according to the NHS. Because of this risk, both reference services advise specific dietary precautions while taking this medication.
The NHS explicitly warns against eating potassium-rich foods such as bananas and avocados while taking spironolactone. MedlinePlus instructs patients to avoid potassium-containing salt substitutes entirely, and advises speaking with a doctor about potassium-rich foods, specifically naming bananas, prunes, raisins, and orange juice.
Managing Weight Changes During Treatment
Body weight can change for many reasons while taking spironolactone, without the medicine being the verified cause. If you notice unexpected changes on the scale, speak with your prescribing doctor to evaluate your overall health and treatment plan. You should not stop taking your prescribed medication without guidance from your healthcare provider.
When to Call a Doctor or NHS 111
You should call a doctor if you experience any of the warning signs documented by MedlinePlus. These signs include muscle weakness, pain, or cramps; pain, burning, numbness, or tingling in the hands or feet; changes in heartbeat; confusion; nausea; extreme tiredness; dry mouth, thirst, or dizziness; unusual bleeding or bruising; yellowing of the skin or eyes; difficulty breathing or swallowing; vomiting blood; blood in stools; decreased urination; or fainting.
For patients in the United Kingdom, the NHS instructs individuals to call NHS 111 if they think they might be experiencing serious side effects or if they have taken more than their prescribed dose of spironolactone.
What to Look For in a Body-Composition Scale
A bioimpedance scale trends body fat and muscle rather than just weight — useful when the number stalls but your composition is improving. The absolute body-fat % isn't lab-accurate, so use it for TRENDS at a consistent time of day. Choose one that syncs to an app so you can watch the trend line.
Frequently Asked Questions
Does spironolactone cause weight gain?
Neither the NHS nor MedlinePlus lists weight gain among the established side effects of spironolactone. The medication is used to treat swelling from fluid build-up, high blood pressure, and heart failure. If you experience weight changes while taking this drug, speak with your prescribing doctor.
What are the common side effects of spironolactone?
The NHS lists common side effects as feeling dizzy, feeling sick (nausea), muscle or leg cramps, feeling tired or low in energy, and breast pain or breast enlargement, including in men. MedlinePlus also lists enlarged or painful breasts and irregular menstrual periods.
Can spironolactone raise potassium?
Yes, the NHS states that spironolactone can sometimes raise potassium levels and cause hyperkalaemia. Patients are warned against eating potassium-rich foods like bananas and avocados, and MedlinePlus instructs individuals to avoid potassium-containing salt substitutes.
When should I call a doctor about spironolactone?
Call a doctor if you develop muscle weakness or cramps; numbness or tingling in the hands or feet; heartbeat changes; confusion; extreme tiredness; dry mouth; unusual bleeding or bruising; yellowing skin or eyes; difficulty breathing or swallowing; vomiting blood; blood in stools; decreased urination; or fainting. The NHS advises calling NHS 111 for serious side effects or an accidental overdose.
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