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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Cardiology · Heart Failure

What Heart Failure Medicine Side Effects Should I Report?

At a Glance

Heart failure medicines can cause mild fatigue or increased urination, but airway swelling, severe breathing trouble, fainting, and dangerous acid buildup or a severe genital infection require emergency help. Vomiting, muscle weakness, a slow heartbeat, or worsening congestion require a same-day call to your care team.

While heart failure medications are essential for improving your heart’s function and keeping you out of the hospital, they are usually prescribed in combination and can cause side effects [1] [2]. It is critical to know that some symptoms require emergency medical help, while others mean you should call your care team right away.

Many early side effects—such as mild fatigue or increased urination—are manageable and may improve over time. Do not make routine changes to your doses on your own, as stopping suddenly can worsen your heart failure. However, if you experience an emergency like airway swelling, you must stop the suspected medicine and seek immediate help [3].

Note: This page covers the most common guideline-directed heart failure medication classes. If you take other medicines, such as digoxin or hydralazine, ask your pharmacist about their specific warning signs.

When to Seek Emergency Help (Call 911 or go to the ER)

Do not wait for a callback from your clinic if you experience any of the following. Do not drive yourself to the emergency room.

  • New swelling of the lips, tongue, face, or throat: This is a sign of a severe allergic reaction called angioedema, which can quickly block your airway [3] [4]. Stop taking any ACE inhibitor, ARB, or ARNI immediately and seek emergency help.
  • Dangerous acid buildup (Euglycemic Ketoacidosis): This rare but life-threatening complication of SGLT2 inhibitors can cause nausea, vomiting, abdominal pain, unexplained breathlessness, unusual fatigue, or confusion [5] [6]. It requires urgent evaluation, even if your blood sugar is normal.
  • Severe respiratory distress: Suddenly being unable to lie flat without gasping for air, having blue lips, or experiencing severe, rapidly worsening shortness of breath are signs of acute fluid buildup in the lungs [7] [8].
  • Fainting or passing out: This can indicate dangerously low blood pressure (hypotension) or severe dehydration [9] [10].
  • Irregular heartbeat with severe symptoms: A new irregular pulse accompanied by chest pain, fainting, or marked weakness is a medical emergency [11] [12].
  • Rapid, severe genital or perineal pain: Extreme pain, swelling, redness, and fever in the genital area can be a rare but life-threatening infection (Fournier gangrene) associated with SGLT2 inhibitors [13] [14].

When to Call Your Care Team Promptly (Same-Day Call)

Contact your doctor’s office the same day if you notice these warning signs so they can adjust your treatment safely:

  • Inability to keep medicines or fluids down: Severe vomiting or diarrhea can cause rapid dehydration and kidney injury, especially when taking diuretics, SGLT2 inhibitors, or blood pressure medicines [15] [16]. Never double your next dose if you miss one.
  • Very slow heartbeat: A dramatically slowed pulse (bradycardia) without fainting [11].
  • New or severe muscle weakness or cramps: This can point to electrolyte imbalances, such as high potassium or kidney changes, which require a blood test to confirm [17] [18].
  • Routine worsening congestion: If you experience a steady worsening of swelling, need extra pillows to sleep, or hit the specific daily weight-gain threshold set by your doctor [19] [20].
  • Persistent dry cough or uncomplicated genital yeast infections: These are known side effects of certain drug classes that warrant a call to discuss medication adjustments [3] [13].

Class-Specific Concerns to Watch For

  • Renin-Angiotensin Drugs (ACE inhibitors, ARBs, and ARNIs): ACE inhibitors are most known for causing a persistent dry cough [3]. Rarely, these drugs cause dangerous airway swelling (angioedema) [4]. ARNIs (like sacubitril/valsartan) can cause symptomatic low blood pressure [9]. Safety rule: Never take an ARNI within 36 hours of an ACE inhibitor [4].
  • MRAs (Mineralocorticoid Receptor Antagonists): Medicines like spironolactone or eplerenone can cause your potassium levels to rise too high (hyperkalemia) or impact your kidney function [17] [18]. Your doctor will need to monitor your blood work periodically. Avoid potassium supplements, potassium-containing salt substitutes, and NSAID pain relievers (like ibuprofen or naproxen), which can worsen these risks [1].
  • Beta-blockers: Medicines like metoprolol or carvedilol slow your heart rate to reduce its workload. They can sometimes slow your pulse too much or cause fatigue and dizziness, especially when first starting [11].
  • SGLT2 inhibitors: Medicines like dapagliflozin or empagliflozin remove sugar through your urine. They can cause genital yeast infections [13]. In rare cases, they can cause the severe emergencies mentioned above: euglycemic ketoacidosis [5] and Fournier gangrene [14].
  • Diuretics (Water Pills): Medicines like furosemide help your body get rid of excess fluid, but they can overcorrect and lead to extreme thirst, dehydration, kidney changes, and low sodium or potassium [16] [15].

Common questions in this guide

Which heart failure medicine side effects mean I should call 911?
Call 911 for new swelling of your lips, tongue, face, or throat; severe trouble breathing; fainting; or an irregular heartbeat with chest pain or marked weakness. Severe genital or perineal pain with swelling, redness, or fever while taking an SGLT2 inhibitor also needs emergency care. If airway swelling occurs while you take an ACE inhibitor, ARB, or ARNI, stop the suspected medicine while seeking help and do not drive yourself.
When should I call my heart failure care team about a medicine side effect?
Make a same-day call if you cannot keep medicines or fluids down, have a very slow heartbeat, new muscle weakness or cramps, persistent dry cough, or a genital yeast infection. Also call if swelling or breathing when lying down is steadily worsening or you reach the daily weight-gain limit your clinician gave you.
What should I do if vomiting or diarrhea prevents me from taking my heart failure medicines?
Contact your care team the same day because fluid loss can cause dehydration, kidney injury, or unsafe changes in blood pressure and electrolytes. Do not double the next dose you miss, and ask your clinician for a personalized sick-day plan before illness occurs.
Can I stop a heart failure medicine if it makes me feel tired or dizzy?
Do not routinely stop or change the dose on your own, because sudden changes can worsen heart failure. Contact your care team to review fatigue, dizziness, low blood pressure, or a slow pulse; airway swelling is an emergency that requires stopping the suspected ACE inhibitor, ARB, or ARNI and getting immediate help.
Which heart failure medicines can raise potassium or affect my kidneys?
Spironolactone and eplerenone can raise potassium and affect kidney function, while diuretics, SGLT2 inhibitors, and other blood pressure medicines can contribute to dehydration or kidney changes. Your clinician may order blood tests after starting or changing treatment; avoid potassium supplements, potassium salt substitutes, and NSAID pain relievers unless your care team says they are safe.
What serious SGLT2 inhibitor side effects should I know about?
Nausea, vomiting, abdominal pain, breathlessness, unusual fatigue, or confusion can signal dangerous acid buildup even when blood sugar is normal and need emergency evaluation. Severe pain, swelling, redness, or fever in the genital or perineal area can signal a rare serious infection and also requires immediate care.

Related questions

Why Can Ejection Fraction Change Between Echocardiograms? Can You Stop Heart Failure Medications After EF Improves? What Do Heart Failure Stages and NYHA Classes Mean? What Are Target Doses for Heart Failure Medicines? What Do Orthopnea and PND Mean in Congestive Heart Failure?
Show more
Do SGLT2 Inhibitors Treat Heart Failure Without Diabetes? Which OTC Drugs and Supplements Are Unsafe in Heart Failure? How Are Low BP and Dizziness Managed in Heart Failure? Why Monitor Kidney Function and Potassium in Heart Failure? What Tests Are Used to Diagnose and Evaluate Heart Failure? How Do Loop Diuretics Work? Side Effects in Heart Failure Can You Have Heart Failure With a Normal Ejection Fraction? What If I Miss or Can't Afford Heart Failure Medicine? What Does Fluid Congestion Mean in Congestive Heart Failure? Can Congestive Heart Failure Be Cured or Reversed? How Do I Find My Dry Weight at Home With Heart Failure? Why Take Multiple Heart Failure Medicines If I Feel Better? Heart Failure vs Heart Attack vs Cardiac Arrest: Which One? What Causes Congestive Heart Failure? Can Treatment Help?

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References

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This page is for informational purposes only and does not constitute medical advice. It cannot replace instructions from your heart-failure clinician or pharmacist, especially during severe symptoms, vomiting, or diarrhea.