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Midamor Side Effects

Generic Name: amiloride

Note: This document contains side effect information about amiloride. Some of the dosage forms listed on this page may not apply to the brand name Midamor.

For the Consumer

Applies to amiloride: oral tablet

Along with its needed effects, amiloride (the active ingredient contained in Midamor) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking amiloride:

More Common

Less Common

  • Agitation
  • back pain
  • blurred vision
  • coma
  • dizziness
  • drowsiness
  • fever
  • hallucinations (seeing things that aren't there)
  • headache
  • irritability
  • labored breathing
  • mood or mental changes
  • seizures (convulsions)
  • stiff neck
  • tightness in the chest
  • unusual tiredness or weakness
  • vomiting
  • wheezing

Rare

  • Arm or jaw pain
  • bloody or black, tarry stools
  • burning while urinating
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • change in vision
  • chest pain, discomfort, or heaviness
  • chills
  • clay-colored stools
  • cold sweats
  • constipation
  • dark urine
  • difficult or painful urination
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
  • fainting
  • fast, pounding, racing, or slow heartbeat or pulse
  • itching
  • light-colored stools
  • loss of appetite
  • loss of vision
  • rash
  • shakiness in the legs, arms, hands, or feet
  • stomach pain, severe
  • sweating
  • trembling or shaking of the hands or feet
  • unpleasant breath odor
  • vomiting of blood or material that looks like coffee grounds
  • yellow eyes or skin

Incidence Not Known

  • Continuing stomach pain
  • cough
  • lower back or side pain
  • pale skin
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen or painful glands
  • unusual bleeding or bruising

Get emergency help immediately if any of the following symptoms of overdose occur while taking amiloride:

Symptoms of Overdose

  • Decreased urination
  • dry mouth
  • increase in heart rate
  • lightheadedness
  • muscle cramps or pain
  • pain or weakness in the hands or feet
  • rapid breathing
  • sunken eyes
  • thirst
  • wrinkled skin

Some side effects of amiloride may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More Common

Less Common

  • Changes in appetite
  • decreased interest in sexual intercourse
  • inability to have or keep an erection
  • loss in sexual ability, desire, drive, or performance

Rare

  • Acid or sour stomach
  • belching
  • continuing ringing or buzzing or other unexplained noise in the ears
  • discouragement
  • disturbed color perception
  • double vision
  • excess air or gas in the stomach or intestines
  • feeling of constant movement of self or surroundings
  • feeling sad or empty
  • frequent urination
  • full or bloated feeling
  • hair loss or thinning of hair
  • hearing loss
  • increased need to urinate
  • increased volume of pale, dilute urine
  • indigestion
  • joint pain
  • leg ache or pain
  • loss of interest or pleasure
  • neck or shoulder ache
  • night blindness
  • overbright appearance of lights
  • pain in the chest below the breastbone
  • passing of gas
  • passing urine more often
  • pressure in the stomach
  • seeing halos around lights
  • sensation of spinning
  • sleepiness or unusual drowsiness
  • sleeplessness
  • stomach fullness, discomfort, or upset
  • stuffy nose
  • swelling of abdominal or stomach area
  • swelling of the breasts or breast soreness in both females and males
  • trouble concentrating
  • trouble sleeping
  • tunnel vision
  • unable to sleep

For Healthcare Professionals

Applies to amiloride: compounding powder, oral tablet

Metabolic

Cases of severe hyponatremia have been reported during hydrochlorothiazide-amiloride (the active ingredient contained in Midamor) therapy. In 3 cases, the patients subsequently did well with hydrochlorothiazide and potassium supplementation, suggesting a significant role for amiloride in the development of their hyponatremia.

Significantly elevated serum uric acid, cholesterol, and triglyceride levels have been associated with combination hydrochlorothiazide-amiloride therapy. These metabolic abnormalities may not be due to amiloride since they are reported during hydrochlorothiazide monotherapy.

Amiloride is known to cause significant elevations in serum aldosterone, renin, and angiotensin II levels.[Ref]

Metabolic side effects are the most common. Amiloride may cause hyperkalemia in up to 10% of patients, although the risk is decreased to about 1% to 2% when thiazide or loop diuretics are coadministered. Patients with diabetes or who are on other potassium-sparing therapy, ACE inhibitors, or potassium supplementation are predisposed to amiloride-induced hyperkalemia.[Ref]

Renal

Renal side effects including renal insufficiency is unusual after amiloride (the active ingredient contained in Midamor) monotherapy because it is only a weak diuretic.[Ref]

Gastrointestinal

Gastrointestinal complaints of diarrhea, nausea, constipation, anorexia, and general abdominal pain occur less than 5% of patients.[Ref]

Nervous system

Nervous system side effects occur in less than 3% of patients, and include headache, weakness, and fatigue. Encephalopathy may be induced by amiloride-associated metabolic changes in some patients with severe liver disease.[Ref]

Cardiovascular

Cardiovascular side effects are mainly limited to the increased risk of hyperkalemia-induced arrhythmias in patients at risk for arrhythmias. Angina pectoris, arrhythmias, and orthostatic hypotension are reported in less than 1% of patients.[Ref]

Genitourinary

Genitourinary problems include rare complaints of impotence. Polyuria and urinary frequency are reported in less than 1% of patients.[Ref]

References

1. McNay JL, Oran E "Possible predisposition of diabetic patients to hyperkalemia following administration of potassium-retaining diuretic, amiloride (MK 870)." Metabolism 19 (1970): 58-70

2. Millar JA, Fraser R, Mason P, Leckie B, Cumming AM, Robertson JI "Metabolic effects of high dose amiloride and spironolactone: a comparative study in normal subjects." Br J Clin Pharmacol 18 (1984): 369-75

3. Vidt DG "Mechanism of action, pharmacokinetics, adverse effects, and therapeutic uses of amiloride hydrochloride, a new potassium-sparing diuretic." Pharmacotherapy 1 (1981): 179-86

4. Tarssanen L, Huikko M, Rossi M "Amiloride-induced hyponatremia." Acta Med Scand 208 (1980): 491-4

5. Svendsen UG, Ibsen H, Rasmussen S, Leth A, Nielsen MD, Dige-Petersen H, Giese J "Effects of amiloride on plasma and total body potassium, blood pressure, and the renin-angiotensin-aldosterone system in thiazide-treated hypertensive patients." Clin Pharmacol Ther 34 (1983): 448-53

6. Davidson C, Burkinshaw L, Morgan DB "The effects of potassium supplements, spironolactone or amiloride on the potassium status of patients with heart failure." Postgrad Med J 54 (1978): 405-9

7. Schiffl H, Schollmeyer P "Clinical efficacy and safety of long-term diuretic treatment in renal parenchymal hypertension." Int J Clin Pharmacol Ther Toxicol 23 (1985): 585-8

8. "Product Information. Midamor (amiloride)." Merck & Co, Inc, West Point, PA.

9. Maddox RW, Arnold WS, Dewell WM "Extreme hyperkalemia associated with amiloride ." South Med J 78 (1985): 365

10. Lynn KL, Bailey RR, Swainson CP, Sainsbury R, Low WI "Renal failure with potassium-sparing diuretics." N Z Med J 98 (1985): 629-33

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

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