Nadolol Drug Interactions: What You Need to Know

Nadolol (brand name Corgard) is a non-selective beta-blocker used for hypertension, angina, and other conditions. Like any medication that affects your heart rate and blood pressure, it can interact with other drugs in ways that are potentially dangerous. This guide covers the most important interactions to be aware of.

How Drug Interactions Work with Nadolol

Nadolol works by blocking beta-adrenergic receptors, which slows your heart and lowers blood pressure. Drug interactions with Nadolol generally fall into a few categories:

• Additive effects — Other drugs that also slow the heart or lower blood pressure can combine with Nadolol to cause dangerously low heart rate or blood pressure
• Masking effects — Nadolol can hide the symptoms of conditions like low blood sugar, making them harder to detect
• Opposing effects — Some drugs can reduce Nadolol's effectiveness
• Rebound effects — Stopping certain drugs while taking Nadolol can cause dangerous spikes in blood pressure or heart rate

Medications That Interact with Nadolol

Major Interactions (Potentially Dangerous)

These combinations require careful monitoring or should be avoided:

• Verapamil (Calan, Verelan) and Diltiazem (Cardizem, Tiazac) — These non-dihydropyridine calcium channel blockers also slow the heart. Combined with Nadolol, they can cause severe bradycardia (dangerously slow heart rate) and heart block. If both are needed, your doctor will monitor you closely.
• Clonidine (Catapres) — If you take both Nadolol and Clonidine for blood pressure, stopping Clonidine suddenly can cause life-threatening rebound hypertension. If discontinuation is needed, Clonidine should be tapered first, and Nadolol stopped several days later.
• Digoxin (Lanoxin) — Both Nadolol and Digoxin slow heart rate. Together, they can cause additive bradycardia. Your doctor may need to monitor your heart rate and Digoxin levels more closely.
• Amiodarone (Cordarone, Pacerone) — This antiarrhythmic also slows the heart. Combined with Nadolol, the risk of severe bradycardia and heart block increases significantly.
• MAO inhibitors — Medications like Phenelzine (Nardil) and Tranylcypromine (Parnate) can potentially cause severe hypertension when combined with beta-blockers.

Moderate Interactions (Requires Monitoring)

• Insulin and oral diabetes medications — Nadolol can mask the warning signs of hypoglycemia (low blood sugar), especially rapid heartbeat and trembling. If you have diabetes, you'll need to monitor blood sugar more frequently. The drugs affected include Insulin, Metformin, Glipizide (Glucotrol), and Glyburide.
• NSAIDs — Ibuprofen (Advil, Motrin), Naproxen (Aleve), Celecoxib (Celebrex) — These common pain relievers can reduce Nadolol's blood-pressure-lowering effect. Occasional use is usually fine, but regular NSAID use may require a blood pressure adjustment.
• Reserpine and other catecholamine-depleting drugs — Can cause additive hypotension (low blood pressure) and bradycardia when combined with Nadolol.
• Anesthetic agents — If you're having surgery, tell your anesthesiologist you take Nadolol. Some anesthetics can enhance the blood-pressure-lowering effect, increasing the risk of hypotension during surgery.
• Epinephrine (EpiPen) — This is an important one. Nadolol can reduce the effectiveness of epinephrine used to treat severe allergic reactions (anaphylaxis). If you carry an EpiPen, make sure all your doctors know you take Nadolol. You may need a higher dose of epinephrine in an emergency.

Supplements and OTC Medications to Watch

Not all interactions involve prescription drugs. Watch out for:

• Decongestants containing pseudoephedrine or phenylephrine (Sudafed, many cold medicines) — These can raise blood pressure, counteracting Nadolol's effect. They may also interact with the beta-blockade to cause blood pressure spikes.
• Melatonin — Some beta-blockers reduce melatonin production. If you have trouble sleeping on Nadolol, melatonin supplements may help, but discuss the dose with your doctor.
• Herbal supplements with cardiac effects — Hawthorn, St. John's Wort, and Ma Huang (ephedra) can interact with beta-blockers. Always tell your doctor about supplements you take.
• Antacids — Aluminum and magnesium-containing antacids may slightly reduce Nadolol absorption. Take them at least 2 hours apart if you use them regularly.

Food and Drink Interactions

• Alcohol — Enhances Nadolol's blood-pressure-lowering effect and can increase dizziness and lightheadedness. Moderate your intake, especially when first starting the medication.
• Food — Nadolol can be taken with or without food. There are no significant food interactions.
• Caffeine — May slightly reduce Nadolol's blood-pressure-lowering effect, but moderate coffee consumption is generally fine.

What to Tell Your Doctor Before Starting Nadolol

Before starting Nadolol, give your doctor a complete picture:

• All prescription medications — Including any heart, blood pressure, diabetes, or psychiatric medications
• All OTC medications — Especially pain relievers (NSAIDs), cold medicines (decongestants), and antacids
• All supplements and herbs — Even "natural" products can interact with Nadolol
• Medical conditions — Especially asthma, COPD, diabetes, kidney disease, thyroid disorders, and any heart conditions
• Upcoming surgeries — Your surgical team needs to know you're on a beta-blocker
• Allergy history — Particularly if you carry an EpiPen, since Nadolol can reduce epinephrine's effectiveness

If you're concerned about a specific interaction, your pharmacist is also an excellent resource. They can check your full medication list for interactions every time you fill a prescription.

Final Thoughts

Nadolol is a safe and effective medication when used properly, but its interactions with other heart-rate-lowering drugs, diabetes medications, and common OTC products are important to understand. The biggest risks come from combining it with other drugs that slow the heart (like Verapamil, Digoxin, or Amiodarone) or stopping Clonidine abruptly while taking it.

Keep an updated medication list and share it with every provider you see. And if you're having trouble finding Nadolol at your pharmacy, Medfinder can help you locate a pharmacy with it in stock.