Spironolactone/Hydrochlorothiazide
“This page provides important general information for pet owners whose animals have been prescribed Spironolactone/Hydrochlorothiazide during a consultation by Dr Noor. Spironolactone/Hydrochlorothiazide for pets in Perth.”
Spironolactone/Hydrochlorothiazide for pets
(speer-on-oh-lak-tone / hye-droe-klor-oh-thye-uh-zide)
Description:
This medicine is a “water pill” combination (a diuretic), meaning it helps the body get rid of extra fluid.
Other Names for this Medication:
- Aldactazide®
Common Dosage Forms:
- For animals: there is no standard veterinary-made product.
- For people: tablets that contain 25 mg/25 mg or 50 mg/50 mg.
- This medicine can also be specially prepared (compounded) into a liquid that is taken by mouth.
This handout does not include every possible detail about this medicine, and it has not been reviewed by the FDA Center for Veterinary Medicine. It is meant to answer common questions, but it does not replace medical advice. If you need more details or have questions about this medicine, contact your veterinarian or your pharmacist.
Key Information
- This medicine (spironolactone with hydrochlorothiazide, also called HCTZ) can be given either with food or without food. If your pet throws up or seems unwell after getting it on an empty stomach, give the next dose with food or a small treat. If vomiting keeps happening, contact your veterinarian.
- This medicine is often used along with other medicines for heart failure. It may also be used to help with signs linked to liver disease.
- Your pet must always be able to reach fresh, clean water while taking this medicine, because spironolactone can make your pet drink more and urinate more.
- This medicine can change the levels of body salts in the blood (electrolytes). Because of this, your veterinarian will need to do regular blood tests to help keep your pet safe.
- Contact your veterinarian right away if your pet develops any of the following:
- skin sores
- itching on the face (in cats)
- ongoing or severe loss of appetite
- vomiting
- diarrhea
- low energy
- faster breathing or harder breathing
- trouble walking or staying balanced
- if your pet stops drinking
- stops urinating
- Use disposable gloves when you handle this medicine.
©2025 Educational Concepts, LLC, a division of Instinct
How is this medication useful?
Spironolactone combined with hydrochlorothiazide (HCTZ) is a diuretic. It works in the kidneys to help remove extra fluid and salt from the body.
- In dogs and cats, this medicine is used together with other drugs to help reduce extra strain on the heart and to lower blood pressure.
- This combination may also help protect the heart muscle.
- In dogs, it has also been used for fluid buildup in the belly that can happen with end-stage liver failure.
What should I tell my veterinarian to see if this medication can be safely given?
Many factors can change how well this medicine works for your pet. Share the following information with your veterinarian so you can make treatment choices together.
- Other medicines can affect spironolactone and HCTZ. Tell your veterinarian and pharmacist about everything your pet receives, including vitamins, supplements, and herbal products. Also include how much you give and how often.
- Tell your veterinarian about any health problems your pet has now or has had before.
- If your pet has been treated for the same problem in the past, explain what was used and whether it helped or did not help.
- If possible, this medicine should not be used in pregnant or nursing animals. Spironolactone may cause birth defects, and HCTZ may lower milk production. If your pet is pregnant or nursing, discuss the risks of using this medicine with your veterinarian.
- Tell your veterinarian and pharmacist about any side effects your pet has had from medicines in the past, including allergic reactions, not wanting to eat, diarrhea, itching, or hair loss.
How long until I will know if this medication is working, and how long will the effects of this medication last?
- This medicine should begin to act within 1 to 2 hours. Even so, you may not be able to see the effects just by watching your pet.
- Your veterinarian will need to do additional tests to check whether the medicine is working the right way.
- The effects do not last long. The medicine stops working within 24 hours. However, the helpful effects may last longer if your pet’s kidneys and/or liver are not working well.
When should this medication not be used or be used very carefully?
No medicine is completely safe for every patient. Your veterinarian will talk with you about any special concerns for your pet.
This drug SHOULD NOT be used in patients:
If your pet fits any of the situations listed, talk with your veterinarian about the risks and benefits.
- Pets that cannot make urine or that have severe kidney disease.
- Pets that have had an allergic reaction to spironolactone, to HCTZ, or to medicines related to HCTZ (for example, chlorothiazide).
- Pets that already have high potassium levels.
- Pets that are pregnant or nursing.
This drug should be used WITH CAUTION in patients:
- Pets with decreased kidney function.
- Pets with diabetes that is not controlled, or other problems where body water, blood sugar, or blood salts (electrolytes) are not balanced.
- Pets that are allergic to “sulfa” drugs. HCTZ is related to sulfa drugs and may trigger an allergic reaction.
- Pets that are vomiting or have diarrhea.
What are the side effects of this medication?
Common but not serious side effects include:
- Drinking more than usual and needing to urinate more often.
- Low energy. This may be temporary and may get better over time.
- Changes in body water and body salts (electrolytes).
- In men, spironolactone can cause breast enlargement. It is not known whether this happens in animals. If your pet’s nipples or breast area becomes larger, contact your veterinarian.
- Vomiting and/or diarrhea.
You do not need to be highly worried if you notice these effects unless they are severe, get worse, or do not go away. If that happens, contact your veterinarian.
Side effects that may be serious or indicate a serious problem:
If you notice any of the following, contact your veterinarian immediately.
- Cats: severe, very itchy sores on the face. This has been seen most often in Maine coon cats.
- Drinking a lot but not urinating.
- Extreme weakness or collapse; unable to stand up.
- Not wanting to eat.
- A fast heartbeat.
- Pale gums.
If my animal gets too much of this medication (an overdose), what should I do?
Giving too much spironolactone with HCTZ can be dangerous. If you see an overdose happen, or you think it may have happened, contact your veterinarian or an animal poison control center right away for instructions.
How should this medication be given?
- To get the intended effect, give this medicine exactly the way your veterinarian prescribed it. Always read the prescription label so you confirm you are giving it correctly.
- Unless your veterinarian gives different instructions, your pet should always have plenty of fresh, clean water available while taking this medicine.
- This medicine may be given with food or without food. If your pet vomits or seems sick after getting it on an empty stomach, try the next dose with food or a small treat. If vomiting continues, contact your veterinarian.
- Because this medicine may make your pet urinate more than usual, try not to give the last dose of the day within a few hours of bedtime. This can help reduce the need for nighttime bathroom trips. Your veterinarian can recommend the best dosing times to help with this. NEVER take away water to try to reduce how often your pet urinates.
- If your pet is receiving a specially made (compounded) liquid, measure it with care. Your veterinarian or pharmacist can provide special measuring spoons or syringes.
- If giving this medicine is difficult, contact your veterinarian or pharmacist for ideas to make dosing easier and to lower stress during medication time.
- This medicine may be used for different lengths of time. Make sure you understand how long your veterinarian wants your pet to stay on it. You may need prescription refills before treatment is finished. Do not stop this medicine without speaking with your veterinarian, because there may be important reasons to keep using it.
What should I do if I miss giving a dose of this medication?
- If you forget a dose, give it as soon as you remember.
- If it is almost time for the next dose, do not give the missed dose. Instead, give the next dose at the regular time.
- After that, continue with the normal schedule.
- Do not give two doses at once and do not give extra doses.
How should I store this medication?
- Keep this medicine at room temperature in the original prescription container that is tightly closed and blocks light, or in an approved dose reminder container (such as a pill organizer).
- If your veterinarian or pharmacist has prepared a special (compounded) form for your pet, follow the storage directions and the expiration date provided for that product. These compounded products are often kept in the refrigerator and must be protected from light and from freezing.
- Store it where children and animals cannot reach it.
Can handling this medication be hazardous to me, my family, or other animals?
- The National Institute for Occupational Safety and Health (NIOSH) lists spironolactone as a hazardous drug. Wearing gloves should be considered when giving this medicine (especially if you are pregnant). This is particularly important for people who are allergic to sulfa medicines.
- If the medicine gets on skin by accident, wash the area well with water. Keep it away from the eyes.
- If a person swallows this medicine by accident, contact a doctor immediately. Doctors can call a Poison Control Center for guidance about human ingestion.
- Keep this and all medicines out of reach of children and other animals.
- Wash your hands after you handle any medicine.
How should I dispose of this medication if I don’t use it all?
- Do not flush this medicine down a toilet and do not pour it into a sink.
- If your area has a community medicine “take-back” program, use that option.
- If there is no take-back program:
- combine the medicine with coffee grounds or cat litter so it is less appealing to children and animals and not easily recognized by people searching through trash
- put the mixture into a sealable plastic bag to prevent leaks, then place it in the regular trash
- Do not keep leftover medicine for later use, and do not give it to anyone else.
What other information is important for this medication?
- This medicine may be prohibited in some animal competitions. Check the rules before entering your animal in a competition or performance while your animal is receiving this medicine.
- Your veterinarian will need to do regular checkups and blood tests while your pet is taking this medicine. Do not skip these important follow-up appointments.
- If you have more questions about this medicine, contact your veterinarian or pharmacist.
©2025 Educational Concepts, LLC, a division of Instinct
“Disclaimer: The information on this page is provided as general educational material only. Every animal’s health situation is unique, and treatment decisions must be based on a full veterinary assessment. Always follow the specific instructions given during your consultation, and contact the prescribing veterinarian if you have any concerns.”