Amiloride and Hydrochlorothiazide: Uses, Dosing, Side Effects
Last updated September 7, 2026.
**Amiloride and hydrochlorothiazide is a single tablet that pairs a potassium-sparing diuretic (amiloride) with a thiazide diuretic (hydrochlorothiazide), a combination water pill used for blood pressure and fluid buildup.** Hydrochlorothiazide makes your kidneys pass more sodium and water into the urine, which lowers blood volume and blood pressure, but it also pushes potassium out. Amiloride works at a different point in the kidney and holds potassium back, so the two together lower blood pressure while keeping potassium closer to normal. The most important safety point is the opposite problem: amiloride can push potassium too high, and high potassium can cause a dangerous heart rhythm, so your potassium and kidney function need blood testing before and during treatment.
What does it treat?
Doctors prescribe this combination for high blood pressure and for edema, meaning fluid buildup that shows up as swollen ankles and feet, puffy legs after sitting, sudden weight gain over a few days, or shortness of breath when lying flat. The edema uses include congestive heart failure and cirrhosis of the liver with ascites, which is fluid collecting in the belly. It is specifically chosen for people who need a thiazide diuretic but who already dropped their potassium too low on hydrochlorothiazide alone, or for whom low potassium would be risky, such as people taking digoxin or those with certain heart rhythm problems. In the United States it is sold as generic amiloride and hydrochlorothiazide tablets and was previously marketed under the brand name Moduretic.
How do you take it?
It comes as an oral tablet containing amiloride hydrochloride 5 mg with hydrochlorothiazide 50 mg. The usual adult starting dose is one tablet a day, and your doctor may raise it to two tablets a day if blood pressure or swelling is not controlled; two tablets a day is the labeled ceiling, and the second tablet can be taken with the first or split between morning and evening. Take it with food to reduce stomach upset, and take the last dose of the day before late afternoon so you are not up at night urinating. Do not use potassium supplements or potassium-based salt substitutes with it unless your doctor tells you to, since amiloride already conserves potassium. If you miss a dose, take it when you remember, but skip it and go back to your regular schedule if your next dose is close, and never double up. Stop the tablet and call your doctor if you have muscle weakness, numbness or tingling, a slow or irregular heartbeat, vomiting or diarrhea that keeps you from drinking, or if you feel faint when you stand up.
Side effects to know
- Common: Expect to urinate more often, especially in the first week or two, and you may notice lightheadedness when standing quickly, headache, tiredness, mild nausea, or leg cramps.
- Serious: Get medical help right away and stop taking it if you have muscle weakness or heaviness, numbness or tingling in the hands, feet, or lips, or a slow, skipping, or pounding heartbeat, which can signal potassium that is too high. Also seek urgent care for confusion, severe headache, or a seizure from low sodium, for sudden eye pain with blurred vision, for a blistering or peeling rash, and for hives with swelling of the lips, tongue, or throat.
Who should not take it?
Do not take this combination if your potassium is already high, if you are taking another potassium-sparing diuretic such as spironolactone, triamterene, or eplerenone, if you take potassium supplements or potassium salt substitutes, if you are not producing urine, or if you have significant kidney impairment or kidney disease from diabetes. Talk to your doctor first if you have any kidney or liver disease, diabetes, gout, lupus, an allergy to sulfa drugs, or if you take an ACE inhibitor such as lisinopril, an ARB such as losartan, aliskiren, trimethoprim, tacrolimus, cyclosporine, lithium, digoxin, or regular NSAIDs like ibuprofen or naproxen, since all of these change your potassium, sodium, or kidney numbers. Tell your doctor if you are pregnant, planning pregnancy, or breastfeeding: FDA labeling notes there are no adequate studies of this combination in pregnant women, thiazides cross the placenta and have been linked to jaundice and low platelets in the newborn, hydrochlorothiazide passes into breast milk, and other blood pressure medicines are usually preferred in pregnancy. Alcohol adds to the drop in blood pressure and the dizziness, so keep intake low and stand up slowly, and skip alcohol entirely on days you feel lightheaded or dehydrated.
When is it an emergency?
Call 911 in the United States if you collapse or faint, have trouble breathing, have chest pain, have a seizure, or have swelling of the face, lips, tongue, or throat with hives. For a suspected overdose, or if someone takes extra tablets by accident, call Poison Control at 1-800-222-1222 right away, even if the person seems fine; overdose mainly causes heavy fluid loss and electrolyte shifts, with signs like severe dizziness, dry mouth and intense thirst, very little urine, vomiting, drowsiness or confusion, muscle weakness, and a slow or irregular pulse. High potassium is the drug-specific red flag to know: weakness in the legs, numbness or tingling, and a heartbeat that feels slow or is skipping beats need same-day evaluation with a blood test and an ECG, not a wait-and-see approach. If you cannot keep fluids down because of vomiting or diarrhea, contact your doctor the same day, since dehydration on this tablet can quickly move both your kidney numbers and your potassium.
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Common questions
What is the maximum dose of amiloride and hydrochlorothiazide?
The labeled maximum is two tablets a day, which is 10 mg of amiloride and 100 mg of hydrochlorothiazide total. Most people start on one tablet daily and stay there. If two tablets are needed, they can be taken together or split into a morning and an evening dose, with the evening dose early enough that you are not woken by urinating. Going above two tablets a day does not add benefit and raises the risk of high potassium and dehydration.
Can I drink alcohol while taking this medicine?
Alcohol lowers blood pressure on its own and adds to the dizziness and lightheadedness this diuretic can cause, especially when you stand up. It also increases fluid loss, which works against the fluid balance the medicine is managing. If you drink, keep it to small amounts, have it with food, and stand up slowly afterward. Skip alcohol on days you already feel lightheaded, are vomiting, or have been out in the heat.
Is it safe during pregnancy or breastfeeding?
Tell your doctor before you start if you are pregnant or trying to become pregnant. FDA labeling states there are no adequate and well controlled studies of this combination in pregnant women, and thiazide diuretics cross the placenta and have been associated with newborn jaundice and low platelet counts. Diuretics also do not treat the swelling of normal pregnancy and are not used for that. Hydrochlorothiazide passes into breast milk, so your doctor will discuss whether to switch medicines or stop nursing; other blood pressure drugs with more pregnancy safety data are usually chosen instead.
Should I take it with food, and what about salt substitutes?
Take it with a meal or a snack to cut down on stomach upset. There is no food you must avoid, but potassium-based salt substitutes such as those sold as light salt or no-salt seasoning are the exception, and you should not use them unless your doctor says to. Large amounts of high potassium foods like potatoes, bananas, oranges, and tomato products can matter too, so ask your doctor whether your diet needs adjusting. Keep drinking normally so you do not get dehydrated.
What are the signs that my potassium is too high?
High potassium often causes muscle weakness that starts in the legs, a heavy or tired feeling in the limbs, and numbness or tingling in the hands, feet, or around the mouth. A heartbeat that feels slow, skipping, or fluttering is the sign that needs the fastest attention. Nausea and unusual fatigue can come with it. These symptoms are not something to sleep on, so stop the tablet and get a same-day blood test and ECG; call 911 if you faint or have chest pain or trouble breathing.
Which medicines interact with amiloride and hydrochlorothiazide?
ACE inhibitors like lisinopril, ARBs like losartan, aliskiren, other potassium-sparing diuretics like spironolactone, and trimethoprim all raise potassium the same way amiloride does, so they need monitoring or avoidance. NSAIDs such as ibuprofen and naproxen reduce the blood pressure effect and can strain the kidneys. Lithium levels rise on thiazides and can reach toxic range. Digoxin is affected by shifting potassium levels, and cyclosporine and tacrolimus also raise potassium. Give your doctor and pharmacist your full list, including over the counter products and supplements.