Amiloride: what it treats, how to take it, and side effects
Last updated September 7, 2026.
**Amiloride is a potassium-sparing diuretic, a water pill that helps your body clear extra salt and fluid without dumping potassium in your urine.** It blocks sodium channels in the last part of the kidney tubule, so you lose sodium and water while potassium and magnesium stay behind. That is why it is usually added to a thiazide or loop diuretic rather than used alone. The one safety point that matters most: amiloride can push potassium too high, which can cause a dangerous heart rhythm, so your potassium and kidney function need blood tests before you start and while you take it.
What does it treat?
Amiloride is used with a thiazide or loop diuretic to treat high blood pressure and the fluid buildup of congestive heart failure, and to prevent or correct the low potassium those other diuretics cause. Doctors reach for it when someone on hydrochlorothiazide or furosemide keeps showing a low potassium level on labs, or has symptoms tied to it like muscle cramps, weakness, or extra heartbeats, and when losing more potassium would be risky, such as in people taking digoxin or with a history of arrhythmia. It is also used in some cases of cirrhosis with ascites and edema. It comes as single-ingredient amiloride 5 mg tablets and as a fixed combination with hydrochlorothiazide, 5 mg of amiloride with 50 mg of hydrochlorothiazide, once sold as Moduretic.
How do you take it?
Amiloride comes as a 5 mg oral tablet, taken by mouth, usually once a day. The label starting dose when it is added to a thiazide or loop diuretic is 5 mg a day; if potassium stays low, the dose can go up to 10 mg a day, and in some people 15 mg or 20 mg a day with close monitoring of blood potassium and kidney function. Do not take more than 20 mg in a day. Take it with food to cut down on stomach upset, and take it in the morning so the extra urination does not keep you up at night. Skip salt substitutes and low sodium salts, which are usually potassium chloride, and do not add potassium supplements unless your doctor specifically tells you to. If you miss a dose, take it when you remember unless your next dose is close, then skip the missed one; never double up. Stop the drug and call your doctor the same day if you notice muscle weakness, numbness or tingling in your hands, feet, or lips, a slow or irregular heartbeat, confusion, or if you cannot keep fluids down because of vomiting or diarrhea, since dehydration changes how the drug behaves.
Side effects to know
- Common: The common effects are mild and often fade: headache, nausea, loss of appetite, diarrhea or constipation, gas, dizziness, tiredness, and passing more urine than usual.
- Serious: Get help right away for signs of high potassium, which include muscle weakness or heaviness in your legs, numbness or tingling, a slow, pounding, or irregular heartbeat, and confusion or feeling like you may pass out. Also stop the drug and seek care for hives, swelling of the face, lips, or tongue, trouble breathing, a rash with blistering or peeling, severe dizziness on standing, or passing little or no urine.
Who should not take it?
Amiloride is not for you if your blood potassium is already above 5.5, if you are not making urine, if you have acute or worsening kidney disease or kidney damage from diabetes, or if you have had an allergic reaction to it. Do not combine it with another potassium-sparing diuretic such as spironolactone, eplerenone, or triamterene, and do not take potassium supplements or potassium-based salt substitutes with it. Talk to your doctor first if you take an ACE inhibitor like lisinopril, an ARB like losartan, a regular NSAID like ibuprofen or naproxen, trimethoprim and sulfamethoxazole, cyclosporine or tacrolimus, or lithium, since all of these either raise potassium further or, in lithium's case, build up to toxic levels. Tell your doctor if you have diabetes, liver disease, or kidney problems, and stop amiloride at least three days before a glucose tolerance test. In pregnancy, FDA labeling reports no evidence of harm in animal studies but no adequate studies in pregnant women, so it is used only if clearly needed; it is not known whether amiloride passes into human breast milk, and it does pass into milk in animals, so you and your doctor decide between continuing the drug and continuing to nurse. Alcohol adds to the dizziness and lightheadedness, especially when you stand up, so keep drinking light or skip it while your dose is being adjusted.
When is it an emergency?
Call 911 if you collapse, faint, have trouble breathing, have chest pain, or have a heartbeat that feels very slow, fluttering, or irregular, and if you have swelling of the face, lips, or tongue, hives, or throat tightness after a dose, which points to a severe allergic reaction. Very high potassium can stop the heart with little warning, so muscle weakness or numbness plus a slow or irregular pulse is an emergency, not a wait and see. If you or someone else takes too much amiloride, call Poison Control at 1-800-222-1222 right away, even if the person feels fine; overdose shows up as dehydration, severe weakness, tingling, low blood pressure, and dangerous potassium levels. Bring the pill bottle or a photo of the label with you to the emergency department.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
What is the maximum dose of amiloride?
The label ceiling is 20 mg a day. Most people start at 5 mg once daily alongside a thiazide or loop diuretic, and the dose moves up to 10 mg only if potassium stays low. Doses of 15 mg or 20 mg a day are used in some people with heart failure or cirrhosis, but only with frequent blood tests. Going above 20 mg does not add benefit and sharply raises the chance of dangerous potassium levels.
Can I drink alcohol while taking amiloride?
An occasional drink is usually fine once your dose is steady and your labs are normal. Alcohol widens blood vessels and adds to the blood pressure drop from the diuretic, so it can make you lightheaded or dizzy when you stand up. Heavy drinking also causes fluid loss and worsens dehydration, which is the setup for electrolyte problems. Skip alcohol entirely in the first weeks after starting or changing the dose, and stand up slowly if you do drink.
Is amiloride safe in pregnancy or while breastfeeding?
FDA labeling reports no evidence of harm in animal reproduction studies but no adequate, well-controlled studies in pregnant women, so amiloride is used during pregnancy only when clearly needed. Diuretics are generally not used to treat normal pregnancy swelling or the high blood pressure of pregnancy, because they reduce blood volume the placenta depends on. It is not known whether amiloride passes into human milk, though it does appear in animal milk, so your doctor will help you choose between the drug and nursing. Tell your care team if you are pregnant, trying to conceive, or breastfeeding before you start.
Should I take amiloride with food?
Yes. Taking it with a meal reduces nausea, appetite loss, and stomach upset, which are the most common complaints. Take it at the same time each day, preferably in the morning, so the extra urination happens during the day. The big food rule is what to avoid: salt substitutes and low sodium salts are almost always potassium chloride, and they can push your potassium into the danger zone. You do not need to avoid ordinary potassium-rich foods like bananas or potatoes unless your doctor tells you to limit them.
What are the signs of an amiloride overdose or of potassium getting too high?
The warning signs overlap: muscle weakness or heaviness in the legs, numbness or tingling in the hands, feet, or around the mouth, unusual tiredness, confusion, and a slow, pounding, or irregular heartbeat. Overdose also causes dehydration, severe dizziness, and very low blood pressure. High potassium can be present with no symptoms at all until the heart rhythm changes, which is why routine blood tests matter more than how you feel. Call Poison Control at 1-800-222-1222 for any suspected overdose, and call 911 for fainting, chest pain, or trouble breathing.
Which medicines interact with amiloride?
Anything else that raises potassium is the main concern: spironolactone, eplerenone, triamterene, potassium supplements, ACE inhibitors such as lisinopril, ARBs such as losartan, trimethoprim and sulfamethoxazole, cyclosporine, and tacrolimus. NSAIDs like ibuprofen and naproxen both raise potassium and blunt the blood pressure benefit, and regular use can strain the kidneys. Lithium levels rise with diuretics and can reach toxic range, so that combination needs close monitoring. Give your doctor or pharmacist a full list including over the counter products and supplements before you start.