Amiloride: what it is and what you need to know

Amiloride is a potassium-sparing diuretic doctors use to treat high blood pressure and fluid buildup (edema). You might hear it by its brand name Midamor or in combination pills like Moduretic (amiloride + hydrochlorothiazide). It helps your body get rid of extra salt and water while keeping potassium from being lost the same way other diuretics do. That sounds good, but it creates a different risk: too much potassium.

How amiloride works and when it's used

Amiloride blocks sodium channels in part of the kidney called the collecting duct. Less sodium reabsorption means less water retained, so blood pressure drops and swelling eases. Doctors often use it alone for mild cases or add it to thiazide diuretics to balance potassium loss. Typical adult doses are 5–10 mg once daily; some people take 5 mg twice daily. Maximum daily doses are usually kept under 20 mg. Your doctor will choose the right dose based on your health and other medicines.

Safety: what to watch for

The main side effect to watch is hyperkalemia — high blood potassium. That can cause muscle weakness, tingling, and dangerous heart rhythm changes. You should not combine amiloride with ACE inhibitors, ARBs, potassium supplements, spironolactone, or other potassium-sparing drugs unless a doctor is closely monitoring you. Avoid salt substitutes that contain potassium. NSAIDs can reduce diuretic effect and raise kidney risk when combined with amiloride.

Before starting amiloride, your provider will check your kidney function and blood potassium. After starting or changing the dose, plan to recheck these labs within about 3–7 days and again at 1–2 weeks, then periodically. If you have moderate-to-severe kidney disease, doctors often avoid amiloride or use a much lower dose because the drug can raise potassium to dangerous levels.

Other mild side effects include dizziness, nausea, or headache. If you feel faint, notice a fast or irregular heartbeat, or develop muscle weakness, contact your provider or seek urgent care — these can be signs of high potassium.

Practical tips: take amiloride at the same time each day, keep up with blood tests, and tell every provider and pharmacist about all your medicines and supplements. Don’t stop the drug suddenly without talking to your doctor. If you’re pregnant, breastfeeding, or have severe kidney problems, discuss alternatives — your doctor will pick the safest choice for you.

Want more specific help? Use this information to talk with your clinician: ask how often to test potassium, whether your other meds are safe with amiloride, and what dose suits your condition. A short conversation now can prevent a big problem later.