Corlanor Side Effects: What to Expect and When to Call Your Doctor

What You Should Know About Corlanor Side Effects

Starting a new heart medication can be stressful, especially when you're not sure what to expect. Corlanor (ivabradine) is a proven treatment for chronic heart failure, but like all medications, it comes with potential side effects.

The good news: most side effects are mild and manageable. This guide covers what's common, what's serious, and exactly when you should call your doctor.

What Is Corlanor?

Corlanor is a prescription medication that slows your heart rate. It works by blocking a specific channel in your heart's natural pacemaker called the HCN channel. Unlike beta-blockers, Corlanor lowers your heart rate without affecting blood pressure or how strongly your heart contracts.

It's prescribed for adults with chronic heart failure who have a resting heart rate of 70 bpm or higher, and for children 6 months and older with heart failure from dilated cardiomyopathy. For a complete overview, see our guide on what Corlanor is and how it's used.

Common Side Effects

These side effects happen in a noticeable number of patients but are usually not dangerous:

Bradycardia (Slow Heart Rate) — ~10% of Patients

This is the most common side effect, and it's directly related to how Corlanor works. Your heart rate may drop lower than intended. Symptoms can include:

• Feeling dizzy or lightheaded
• Fatigue or weakness
• Feeling like your heart is beating slowly

Your doctor will monitor your heart rate closely, especially during the first few weeks. If your resting heart rate drops below 50 bpm, your dose will be reduced.

Phosphenes (Visual Brightness) — ~5% of Patients

This is the most unique side effect of Corlanor. Phosphenes are brief episodes of enhanced brightness in a limited area of your visual field. They can look like:

• Flashes or halos of light
• Brief bright spots
• A shimmering or flickering effect

Phosphenes are usually triggered by sudden changes in light and tend to happen in the first few months of treatment. They are temporary, not harmful to your eyes, and often go away on their own over time.

Other Common Side Effects

• Hypertension (high blood pressure) — about 9% of patients
• Atrial fibrillation (irregular heartbeat) — about 5% of patients
• Dizziness — especially when standing up quickly
• Fatigue — feeling more tired than usual
• Nausea — usually mild

Serious Side Effects — When to Call Your Doctor

Some side effects need immediate medical attention. Call your doctor right away if you experience:

Symptomatic Bradycardia

If your heart rate gets too low and you experience:

• Severe dizziness or feeling like you might faint
• Extreme fatigue or confusion
• Shortness of breath that's new or worse than usual

This is different from mild bradycardia. If you feel significantly worse or faint, seek emergency care.

Atrial Fibrillation

About 5% of patients on Corlanor develop atrial fibrillation, an irregular heartbeat. Watch for:

• Heart pounding, fluttering, or racing
• Chest discomfort
• Unusual shortness of breath
• Feeling dizzy or weak

If you develop atrial fibrillation, your doctor may need to stop Corlanor, since the medication only works in patients with a regular (sinus) rhythm.

Conduction Disturbances

Rarely, Corlanor can cause electrical signaling problems in the heart, including first-degree AV block or bundle branch block. Your doctor will monitor this with regular ECGs.

Special Populations

Pregnancy — Boxed Warning

Corlanor carries a boxed warning (the FDA's most serious warning) about fetal toxicity. Women who are pregnant or may become pregnant should not take Corlanor. If you're of childbearing age, your doctor will discuss effective contraception before starting treatment. If you become pregnant while taking Corlanor, contact your doctor immediately.

Breastfeeding

Corlanor is not recommended while breastfeeding, as the medication may pass into breast milk.

Children

Corlanor is approved for children 6 months and older with heart failure from dilated cardiomyopathy. Side effects in children are similar to adults, with bradycardia being the most common.

Older Adults

No dose adjustment is needed for older adults, but they may be more sensitive to bradycardia and should be monitored closely.

How to Manage Side Effects

Here are practical tips for dealing with Corlanor side effects:

• Take it with food. Corlanor should be taken with meals, twice daily. This can help reduce nausea.
• Monitor your heart rate. Check your resting heart rate regularly. A simple pulse check or inexpensive heart rate monitor can help you catch bradycardia early.
• Avoid sudden light changes. If phosphenes bother you, avoid going from dark to bright environments too quickly. They usually fade within a few months.
• Don't skip doses or stop suddenly. Talk to your doctor before making any changes to your dose.
• Watch for grapefruit. Grapefruit juice can increase Corlanor levels in your body. Avoid large amounts. Learn more about Corlanor drug interactions.
• Keep all follow-up appointments. Your doctor needs to check your heart rate and adjust your dose, especially in the first few weeks.

Final Thoughts

Most people who take Corlanor tolerate it well. The most common side effects — bradycardia and phosphenes — are manageable and often improve over time. The key is staying in close contact with your doctor, especially during the first few weeks of treatment.

If you're having trouble finding Corlanor at your pharmacy, MedFinder can help you locate pharmacies with stock near you.