Understanding heart failure and weight loss medications
Heart failure affects how your body processes medications, including Mounjaro. When your heart doesn’t pump efficiently, it can alter how drugs circulate through your system and potentially change their effects.
Heart failure is classified into two main types based on ejection fraction (the percentage of blood your heart pumps out with each contraction), according to the European Society of Cardiology guidelines:
Heart failure with reduced ejection fraction (HFrEF): Your heart muscle doesn’t contract effectively, typically with an ejection fraction below 40%. This was traditionally called “systolic heart failure.”
Heart failure with preserved ejection fraction (HFpEF): Your heart pumps normally but doesn’t relax properly between beats, making it harder to fill with blood. The ejection fraction remains normal (usually above 50%). This was previously called “diastolic heart failure.”
The type of heart failure you have influences how suitable Mounjaro might be for you. Recent research has shown particularly promising results for people with HFpEF, which is often associated with obesity.
Understanding your heart failure classification, current management, and overall cardiovascular health helps determine whether Mounjaro is appropriate for your specific situation.
How Mounjaro affects heart function
Unlike some medications that can strain the cardiovascular system, research suggests Mounjaro may actually provide heart benefits for many patients.
One study found that tirzepatide improved several key markers of heart health in patients with obesity:
- Reduced inflammation markers associated with heart damage
- Improved insulin sensitivity, which benefits heart metabolism
- Decreased fat deposits around the heart (epicardial fat)
- Supported healthy blood pressure changes without causing dangerous drops
The STEP-HFpEF trial specifically examined semaglutide (a similar GLP-1 medication) in heart failure patients with preserved ejection fraction (HFpEF) and found that participants taking the medication showed:
- Improved exercise capacity measured by the 6-minute walk test
- Better quality of life scores on heart failure questionnaires
- Reduced hospitalisations for heart failure compared to placebo
- Significant weight loss averaging 13.3% of body weight after 52 weeks
The STEP-HFpEF findings, along with early results from the ongoing SUMMIT study examining tirzepatide in heart failure, suggest that GLP-1 receptor agonists may be particularly beneficial for heart failure patients.
However, there are important considerations for people with existing heart failure:
Fluid balance: Mounjaro can cause nausea and reduced appetite, which may affect hydration. For patients with heart failure who may already be taking diuretics, maintaining proper fluid balance is crucial.
Blood pressure effects: Weight loss from Mounjaro often improves blood pressure, which benefits heart health. However, if you take blood pressure medications for heart failure, your doses may need adjusting as you lose weight to prevent hypotension (low blood pressure).
Heart rate considerations: Some patients may experience mild changes in heart rate when starting Mounjaro. Your cardiologist should monitor this, particularly if you take beta-blockers or other heart-rate controlling medications.
Special considerations for different types of heart failure
Your experience with Mounjaro will vary depending on your specific type of heart failure:
For patients with HFpEF (preserved ejection fraction)
Research shows particularly promising results if you have HFpEF, which is often associated with obesity. A 2023 study demonstrated that GLP-1 receptor agonists significantly improved:
- Exercise capacity (measured by peak VO2)
- Kansas City Cardiomyopathy Questionnaire scores (measuring quality of life)
- NT-proBNP levels (a marker of heart failure severity)
- Six-minute walk distances
If you have HFpEF, weight loss is often a cornerstone of treatment, and Mounjaro may provide both weight reduction and specific cardiovascular benefits.
For patients with HFrEF (reduced ejection fraction)
Research on tirzepatide specifically for HFrEF is limited, but the overall cardiovascular benefits observed in patients taking Mounjaro and other GLP-1 medications, such as semaglutide (Ozempic/Wegovy), suggest a potential benefit.
If you have HFrEF, your cardiologist will need to carefully assess your current ejection fraction, medication regimen, and overall stability before considering Mounjaro.
Medication interactions and adjustments
Heart failure patients typically take multiple medications that could interact with Mounjaro. Here’s what you need to know based on the NICE guidelines for heart failure management:
Diuretics (water pills): As you lose weight on Mounjaro, you may need reduced doses of diuretics like furosemide or bumetanide to prevent dehydration or electrolyte imbalances.
ACE inhibitors/ARBs: These medications (like ramipril, lisinopril, or candesartan) are cornerstones of heart failure treatment. Weight loss typically improves blood pressure, so your doctor may need to adjust doses to prevent blood pressure from dropping too low.
Beta-blockers: Medications such as bisoprolol, carvedilol, or metoprolol regulate heart rate and decrease cardiac workload. Your doctor should monitor for any additive effects with Mounjaro, particularly during dose adjustments.
SGLT2 inhibitors: Medications like empagliflozin or dapagliflozin are increasingly used for heart failure. While generally compatible with Mounjaro, the combination requires monitoring for dehydration and blood sugar effects.
MRAs (spironolactone, eplerenone): These potassium-sparing diuretics require careful monitoring when combined with any medication that affects kidney function or fluid balance.
Your prescribing clinician should coordinate with your cardiologist to ensure all your heart failure medications remain appropriate as your weight changes.
Regular medication reviews are essential during the first few months of Mounjaro treatment.
Monitoring requirements for heart failure patients
Taking Mounjaro with heart failure requires more frequent monitoring than for people with normal heart function.
Based on the European Society of Cardiology guidelines, your healthcare team should track several key markers:
Heart function tests: Echocardiograms to assess ejection fraction and other heart parameters should be performed before starting Mounjaro and periodically during treatment, typically every 6-12 months.
NT-proBNP levels: This blood test marker of heart strain should be checked every 3-4 months initially to ensure heart failure isn’t worsening.
Fluid status assessment: Regular checks for signs of fluid overload (weight gain, swelling, shortness of breath) or dehydration (dizziness, excessive thirst).
Blood pressure and heart rate: Weekly home monitoring is recommended, as your medication needs may change with weight loss.
Electrolyte levels: Sodium, potassium, and other electrolytes should be monitored more frequently, particularly if you experience significant nausea or reduced appetite.
Medication review: Regular assessment of all your heart failure medications, as doses may need adjusting with weight loss.
Exercise capacity: Simple tests like the 6-minute walk test can help track how your functional capacity is changing.
Your cardiologist should coordinate this monitoring with your other healthcare providers.
Don’t attempt to manage this monitoring independently, as the interaction between heart failure, weight loss, and multiple medications requires professional oversight.
NHS guidance and eligibility
NHS England guidelines for GLP-1 medications emphasise the importance of specialist input for patients with complex conditions like heart failure.
While Mounjaro isn’t specifically contraindicated for most heart failure patients, accessing it through the NHS requires meeting specific criteria.
NHS eligibility for weight management services:
- BMI ≥40 with weight-related health problems
- Evidence of previous weight loss attempts
- Willingness to engage with lifestyle support
Private prescription considerations: If you don’t meet NHS criteria, private prescriptions are available. However, ensure your private prescriber:
- Reviews your complete cardiac history
- Coordinate with your cardiologist
- Provides appropriate monitoring schedules
- Has experience with heart failure patients
Practical strategies for heart failure patients on Mounjaro
If you have heart failure and are starting Mounjaro, these practical strategies can help you maximise benefits while minimising risks.
Stay adequately hydrated: Drink sufficient fluids throughout the day, even if your appetite decreases. This is especially important if you take diuretics.
Monitor daily weights: Weigh yourself each morning after using the toilet and before eating. Sudden weight changes (1-2kg overnight) can indicate fluid retention requiring medical attention.
Track heart failure symptoms: Keep a simple diary of symptoms, such as shortness of breath, swelling, fatigue, and changes in exercise tolerance, to discuss with your healthcare team.
Follow a diet based on whole foods: Focus on whole foods like meat, fish, seafood, fruits, vegetables, nuts, seeds, and high-fibre carbohydrates. Reduce your consumption of ultra-processed foods.
Adjust physical activity gradually: As you lose weight, you may find exercise becomes easier. Increase activity slowly, with guidance from your cardiac rehabilitation team if available.
Have a medication plan: Work with your healthcare team to develop a plan for adjusting heart failure medications as you lose weight. Don’t change doses without medical supervision.
Know warning signs: Be aware of symptoms that warrant immediate medical attention, such as severe shortness of breath, chest pain, palpitations, or dizziness.
Frequently asked questions about Mounjaro and heart failure
Will Mounjaro worsen my heart failure?
Current research suggests Mounjaro doesn’t worsen heart failure and may provide benefits, particularly for HFpEF. However, proper monitoring is essential to ensure your individual response is positive.
How does weight loss affect heart failure?
Weight loss typically improves heart failure by reducing cardiac workload, improving lung function, decreasing inflammation, and enhancing the effectiveness of heart failure medications.
Can I take Mounjaro if I’ve had a heart attack?
Most patients with previous heart attacks can take Mounjaro after full recovery (typically 3-6 months post-event) with cardiologist approval.
Recent research suggests that GLP-1 medications may actually reduce the risk of future cardiovascular events.
Should I stop my heart failure medications when starting Mounjaro?
Never stop heart failure medications without medical guidance. While doses may need adjustment as you lose weight, these medications remain essential for heart function.
Is Mounjaro safe with an implanted cardiac device (pacemaker/defibrillator)?
Yes, Mounjaro is generally safe with cardiac devices. The medication doesn’t interfere with device function, but your electrophysiologist should be informed when starting any new treatment.
What if I experience heart palpitations on Mounjaro?
Report any new or worsening palpitations to your healthcare team immediately. While mild heart rate changes can occur with GLP-1 medications, significant palpitations require evaluation.
How will I know if Mounjaro is helping my heart failure?
Improvements in exercise tolerance, reduced shortness of breath, decreased swelling, lower NT-proBNP levels, and better echocardiogram results all suggest heart benefits from treatment.
Take home message
You can take Mounjaro if you have heart failure, but only with proper medical supervision and coordination between your healthcare providers.
Recent research suggests that rather than posing risks, Mounjaro may offer specific benefits for heart failure patients, particularly those with preserved ejection fraction (HFpEF) and obesity.
Close monitoring of heart function, fluid status, and medication interactions is essential, particularly during the initial months of treatment.
If you have heart failure and want to explore Mounjaro, speak to your cardiologist about whether it’s appropriate for your specific cardiac condition and how to ensure safe monitoring throughout treatment.
The combination of appropriate medical supervision, weight loss, and heart-healthy lifestyle changes provides the best foundation for improving both heart function and overall quality of life.
Second Nature's Mounjaro programme
Second Nature provides Mounjaro as part of our Mounjaro weight-loss programme
Why choose Second Nature over other medication providers, assuming you’re eligible?
Because peace of mind matters.
We’ve had the privilege of working with the NHS for over eight years, helping people across the UK take meaningful steps toward a healthier, happier life.
Our programmes are designed to meet people where they are, whether that means support with weight loss through compassionate one-to-one health coaching, or access to the latest weight-loss medications (like Mounjaro) delivered alongside expert care from a multidisciplinary team of doctors, psychologists, dietitians, and personal trainers.
At the heart of everything we do is a simple belief: real, lasting change comes from building better habits, not relying on quick fixes. We’re here to support that change every step of the way.
With over a decade of experience, thousands of lives changed, and a long-standing record of delivering programmes used by the NHS, we believe we're the UK’s most trusted weight-loss programme.
We hope to offer you something invaluable: peace of mind, and the support you need to take that first step.
