Labetalol Drug Interactions You Need to Know About

Labetalol is an effective blood pressure medication, but like many drugs, it can interact with other medications, supplements, and even certain foods. Some interactions are minor, while others can be dangerous.

This guide covers the most important Labetalol drug interactions so you can have an informed conversation with your doctor and pharmacist.

How Drug Interactions Work

A drug interaction happens when one substance changes how another substance works in your body. This can happen in several ways:

• Additive effects — Two drugs that do similar things amplify each other's effects (for example, two blood-pressure-lowering drugs can cause your pressure to drop too low).
• Blocking metabolism — One drug slows down how your body breaks down another, causing the second drug to build up to higher-than-normal levels.
• Masking symptoms — One drug hides the warning signs of a problem caused by another.

Labetalol, as a combined alpha-beta blocker, has interactions related to all three of these mechanisms.

Medications That Interact With Labetalol

Major Interactions

These interactions can be serious. Your doctor needs to know if you're taking any of these:

• Cimetidine (Tagamet) — This heartburn medication increases Labetalol's bioavailability, meaning your body absorbs more of it. This can lead to excessive blood pressure lowering and increased side effects. If you need an antacid, ask your doctor about alternatives like Famotidine (Pepcid).
• Other beta blockers — Taking Labetalol with another beta blocker (like Metoprolol, Atenolol, or Propranolol) can cause additive effects including dangerously slow heart rate, low blood pressure, and heart failure.
• Calcium channel blockers (Verapamil, Diltiazem) — Combining these with Labetalol increases the risk of severe bradycardia (slow heart rate) and heart failure. Dihydropyridine calcium channel blockers like Nifedipine or Amlodipine carry less risk but still require monitoring.
• Halothane and halogenated anesthetics — If you're having surgery, tell your anesthesiologist you take Labetalol. These anesthetics combined with Labetalol can cause severe, synergistic hypotension.
• MAO inhibitors — Combining Labetalol with MAO inhibitors (Phenelzine, Tranylcypromine, Selegiline) can cause unpredictable blood pressure changes.
• Nitroglycerin — Both lower blood pressure, and the combination can cause excessive hypotension. This needs careful monitoring if both are used.

Moderate Interactions

These interactions are less dangerous but still worth knowing about:

• Insulin and oral diabetes medications (Metformin, Glipizide, Glyburide) — Labetalol can mask the symptoms of low blood sugar (hypoglycemia), particularly rapid heartbeat and trembling. If you have diabetes, monitor your blood sugar more frequently when starting Labetalol.
• Clonidine (Catapres) — If you're taking both Labetalol and Clonidine and need to stop them, Labetalol should be discontinued first (several days before Clonidine) to avoid rebound hypertension.
• NSAIDs (Ibuprofen, Naproxen, Diclofenac) — Non-steroidal anti-inflammatory drugs can reduce the blood-pressure-lowering effect of Labetalol. Occasional use is usually fine, but chronic NSAID use may make your blood pressure harder to control.
• Digoxin (Lanoxin) — Both Labetalol and Digoxin can slow the heart rate. Together, they increase the risk of bradycardia. Your doctor will monitor your heart rate closely.
• Tricyclic antidepressants (Amitriptyline, Nortriptyline) — May increase the risk of tremor when combined with Labetalol.

Supplements and Over-the-Counter Medications to Watch

It's not just prescription drugs that can interact with Labetalol:

• Pseudoephedrine and Phenylephrine — Found in many cold and sinus medications (Sudafed, some formulations of DayQuil). These are alpha-agonists that can raise blood pressure and counteract Labetalol's effects. Always check the label of cold medicines or ask your pharmacist.
• Potassium supplements — Labetalol can occasionally cause elevated potassium levels (hyperkalemia). Taking extra potassium without medical supervision may worsen this risk.
• Herbal blood pressure supplements — Supplements like Hawthorn, Garlic extract, or CoQ10 that claim to lower blood pressure can have additive effects with Labetalol. Tell your doctor if you use any herbal products.

Food and Drink Interactions

• Food — Food increases Labetalol absorption. This isn't dangerous, but you should take it consistently — either always with food or always without — so your body gets a predictable dose each time.
• Alcohol — Alcohol lowers blood pressure and causes dizziness on its own. Combined with Labetalol, these effects are amplified. Limit alcohol intake and be cautious, especially when you first start the medication.
• Grapefruit — Unlike some other heart medications, Labetalol does not have a significant grapefruit interaction.

What to Tell Your Doctor

Before starting Labetalol, give your doctor a complete picture of everything you take:

1. All prescription medications — including eye drops (some glaucoma drops are beta blockers).
2. Over-the-counter drugs — especially cold medicines, pain relievers (NSAIDs), and antacids.
3. Vitamins and supplements — including potassium, herbal products, and fish oil.
4. Recreational substances — Cocaine and amphetamines have dangerous interactions with Labetalol in the context of cardiovascular stress.
5. Upcoming surgeries — Your anesthesiologist needs to know you're taking Labetalol.

Keep an updated medication list and bring it to every doctor visit and pharmacy interaction. Many pharmacies also offer drug interaction checks — ask your pharmacist to review your full list when you pick up a new prescription.

Final Thoughts

Labetalol is safe and effective when used correctly, but its interactions with other medications are real and important. The biggest risks involve other blood-pressure-lowering drugs, certain heart medications, and anesthetics.

The best thing you can do is be transparent with your healthcare team about everything you take. For more about Labetalol, check out our guides on side effects and how it works.

Need to fill your Labetalol prescription? Search Medfinder to find it in stock near you.