Prescription pillsWhat is Spironolactone?

Spironolactone is in the family of medications known as diuretics (water pill). It blocks the effects of the hormone aldosterone, resulting in water loss by the kidneys, and may decrease scarring/ fibrosis within the heart muscle. It is classified as a potassium sparing diuretic, as it also increases the amount of potassium retained by the kidneys.


  • Used to delay onset of congestive heart failure in cases of degenerative valve disease and dilated cardiomyopathy
  • Often used along with lasix in the treatment of congestive heart failure in both dogs and cats, especially in patients with low potassium levels
  • Also used in certain adrenal gland diseases (hyperaldosteronism) and in some cases of abdominal fluid secondary to low blood protein levels

Adverse Effects

[please contact CVCA should any of these symptoms be noted]

  • Loss of appetite, vomiting or diarrhea are the most common side effects
  • Minty taste can cause drooling in cats
  • Can result in high potassium levels, especially when used with an ACEi (enalapril/benazepril)
  • Dehydration and increases in kidney values infrequently noted
  • Facial itching as an uncommon side effect in cats

Client Information

  • Recommended to be given with food due to its bitter taste, especially in cats
  • Comes in a tablet form, but can be reformulated into chewables or flavored liquid
  • Please contact CVCA should your pet require anesthesia, as dose adjustments may be necessary
  • Close monitoring of blood chemistry profiles are indicated to monitor kidney function and potassium levels
  • Contraindicated in patients with Addison’s disease or elevated potassium levels

Interactions with Other Drugs

  • Potential for high potassium levels when used with an ACEi (enalapril, benazepril)
  • Can increase digoxin levels
  • Concurrent use of a nonsteroidal antinflammatories (Rimadyl, Deramaxx, Metacam) may decrease the effectiveness
  • The doctors at CVCA have taken this into account, however, please feel free to contact CVCA regarding any concurrent medications your pet may be prescribed

Standard Dosage Forms

Spironolactone Tablets – 25mg, 50mg, 100mg


(Spironolactone, Aldactone)

Drug Handouts