Propranolol Drug Interactions You Need to Know About

Propranolol is a widely prescribed beta-blocker used for high blood pressure, migraines, tremor, and anxiety. It's generally safe and well-tolerated — but it interacts with a significant number of other medications, supplements, and even certain foods.

Some of these interactions are minor. Others can be dangerous. This guide covers the most important ones so you know what to watch for and what to tell your doctor.

How Drug Interactions Work with Propranolol

Drug interactions with Propranolol happen in a few ways:

• Additive effects — Another medication does the same thing as Propranolol (like slowing the heart), doubling the effect to a dangerous level.
• Blocking metabolism — Some drugs slow down the liver enzymes (CYP2D6 and CYP1A2) that break down Propranolol, causing it to build up to higher-than-expected levels in your blood.
• Speeding up metabolism — Other drugs rev up those same enzymes, clearing Propranolol from your system too quickly so it stops working well.
• Masking symptoms — Propranolol can hide warning signs of other conditions (like low blood sugar in diabetes), making them harder to catch.

Propranolol is metabolized primarily by the liver through CYP2D6 and CYP1A2 enzymes. Any drug that affects these pathways can change how much Propranolol is in your system.

Major Drug Interactions

These combinations can be dangerous and may require dose adjustments, extra monitoring, or avoidance altogether:

Calcium Channel Blockers

Verapamil (Calan, Verelan) and Diltiazem (Cardizem, Tiazac) — Both slow the heart rate and reduce blood pressure. Combined with Propranolol, the risk of severe bradycardia (dangerously slow heart rate), heart block, and hypotension increases significantly. If you must take both, your doctor will monitor you closely.

Other Antiarrhythmics

Amiodarone (Cordarone, Pacerone) and Digoxin (Lanoxin) — These drugs also slow heart rate and cardiac conduction. Adding Propranolol compounds the effect, increasing the risk of heart block and cardiac arrest.

MAO Inhibitors

Phenelzine (Nardil), Tranylcypromine (Parnate), and Selegiline (Emsam) — MAOIs combined with Propranolol can cause severe, unpredictable changes in blood pressure. This combination should be avoided.

Insulin and Oral Diabetes Medications

Insulin, Metformin (Glucophage), Glipizide (Glucotrol), and other glucose-lowering drugs — Propranolol masks the typical warning signs of low blood sugar (hypoglycemia), particularly the fast heartbeat and trembling. It may also prolong hypoglycemic episodes. If you're diabetic and take Propranolol, monitor your blood sugar more frequently.

CYP2D6 and CYP1A2 Inhibitors

These medications slow down Propranolol's metabolism, raising its levels in your blood and increasing the risk of side effects:

• Fluoxetine (Prozac) — A common SSRI and strong CYP2D6 inhibitor
• Fluvoxamine (Luvox) — A strong CYP1A2 inhibitor; can dramatically increase Propranolol levels
• Quinidine — An antiarrhythmic and CYP2D6 inhibitor
• Cimetidine (Tagamet) — An older heartburn medication that inhibits multiple CYP enzymes

Clonidine (Catapres)

If you're taking both Clonidine and Propranolol, do not stop Clonidine first. Discontinuing Clonidine while still on Propranolol can trigger a dangerous rebound spike in blood pressure. If both need to be stopped, Propranolol should be tapered first.

Thioridazine

Propranolol can increase Thioridazine levels in the blood, raising the risk of QT prolongation and potentially fatal heart rhythm changes. This combination is contraindicated.

Epinephrine

In patients on Propranolol, Epinephrine (used for severe allergic reactions) may be less effective and can paradoxically cause a dangerous rise in blood pressure. If you carry an EpiPen and take Propranolol, make sure your allergist and emergency contacts know.

Moderate Drug Interactions

These interactions are worth knowing about but can usually be managed with monitoring or dose adjustments:

• NSAIDs — Ibuprofen (Advil, Motrin) and Naproxen (Aleve) — May reduce Propranolol's blood-pressure-lowering effect. Occasional use is usually fine, but chronic daily use of NSAIDs can undermine your blood pressure control.
• CYP enzyme inducers — Rifampin and Phenobarbital — Speed up Propranolol's metabolism, potentially making it less effective. Your doctor may need to increase your Propranolol dose.
• Aluminum-containing antacids (Maalox, Mylanta) — Can reduce how well Propranolol is absorbed. Take them at least 2 hours apart.
• Warfarin (Coumadin) — Propranolol may increase Warfarin levels, raising the risk of bleeding. More frequent INR monitoring may be needed.
• Theophylline (Theo-24, Elixophyllin) — Propranolol reduces Theophylline clearance, which can increase Theophylline to toxic levels. This combination also poses a risk for asthma patients since Propranolol can worsen breathing.
• Haloperidol (Haldol) — Levels of both drugs may increase when taken together.
• SSRIs (Sertraline, Paroxetine, Citalopram) — Beyond Fluoxetine and Fluvoxamine (which are strong inhibitors), other SSRIs may also modestly increase Propranolol levels through CYP2D6 inhibition.

Supplements and OTC Drugs to Watch

Don't forget that over-the-counter products and supplements can also interact with Propranolol:

• Decongestants (Pseudoephedrine, Phenylephrine) — Found in many cold and sinus medications. These raise blood pressure and heart rate, working against Propranolol. Check the labels of cold medicines like Sudafed, Dayquil, and Mucinex-D.
• Cimetidine (Tagamet) — Available OTC for heartburn. Inhibits CYP enzymes and raises Propranolol levels. Consider Famotidine (Pepcid) instead, which doesn't have this interaction.
• Herbal supplements — St. John's Wort may reduce Propranolol effectiveness by inducing CYP enzymes. Ephedra (Ma Huang) can counteract Propranolol's effects and raise blood pressure.
• Melatonin — Propranolol can suppress natural melatonin production, potentially worsening insomnia. Taking a melatonin supplement may help but discuss the timing with your doctor.

Food and Drink Interactions

• Food — Food increases the absorption of Propranolol. This isn't necessarily bad, but you should take it consistently — either always with food or always without — to keep blood levels steady.
• Alcohol — Both Propranolol and alcohol lower blood pressure. Drinking while on Propranolol can cause excessive drops in blood pressure, leading to dizziness, lightheadedness, or fainting.
• Grapefruit juice — May slightly increase Propranolol levels. The effect is mild compared to some other medications, but it's worth noting if you drink grapefruit juice regularly.
• Caffeine — While not a classic drug interaction, caffeine raises heart rate and blood pressure — the opposite of what Propranolol does. Excessive caffeine may reduce Propranolol's effectiveness.

What to Tell Your Doctor

Before starting Propranolol — or at any follow-up visit — make sure your doctor knows about:

• Every prescription medication you take, including eye drops (Timolol eye drops are a beta-blocker and can add to Propranolol's effects)
• All OTC medications, especially cold medicines, pain relievers, and antacids
• Supplements and herbal products
• How much alcohol and caffeine you consume
• Any recent changes to your medication list, even if another doctor made the change

If you're seeing multiple specialists, make sure each one knows you're on Propranolol. Drug interactions are more common when multiple providers are prescribing without full visibility into your medication list.

For a broader look at Propranolol's side effects and safety profile, see our dedicated guide. And if you're looking for Propranolol at a good price, check out our savings guide.

Final Thoughts

Propranolol is a safe and effective medication for millions of people — but it doesn't exist in a vacuum. What you take alongside it matters. The most important thing you can do is keep an updated medication list and share it with every healthcare provider you see.

If you're not sure whether something you're taking interacts with Propranolol, ask your pharmacist. They're trained to catch interactions and can often answer your question in minutes.

Need help finding Propranolol at a pharmacy near you? Medfinder can show you which pharmacies have it in stock right now.