Propranolol interactions to avoid

Propranolol is a medication commonly prescribed to treat conditions such as high blood pressure (hypertension), heart-related conditions (such as chest pain, angina, atrial fibrillation, and arrhythmia), essential tremor, and migraine headaches. It belongs to a class of drugs known as beta blockers, which help the heart beat slower and more steadily. Available under the brand names Inderal LA and InnoPran XL, this medication is typically used with other medicines to manage heart rate and blood pressure. As a result, propranolol may help reduce the risk of heart attacks and strokes.

If you’ve been prescribed propranolol, you should be aware of potential interactions with other prescription drugs. As many people who take propranolol take other medications, there may be an increased risk of drug interactions that could lead to severe adverse effects. In some cases, interactions may result in increased or decreased levels of propranolol in the body. In other cases, propranolol may affect the levels of other medications, leading to potential complications. 

Read on to learn about the potential interactions of propranolol and other drugs. That way, you can take the necessary precautions to ensure safe and effective treatment. 

Propranolol-drug interactions

Propranolol can interact with various medications, including prescription, over-the-counter, and certain supplements. As propranolol is heavily processed in the liver by certain enzymes, it can interact with many medications that affect or are processed by the same enzymes. Some of the most serious interactions may involve heart rhythm medications, migraine medications, and antimicrobial agents.

Heart rhythm medications

Propranolol can interact with antiarrhythmics or medications used to regulate heart rhythm. Combining these drugs may lead to additive negative effects on heart rate and function. Depending on the medication, blood levels of propranolol may be increased, leading to increased side effects. Examples of heart rhythm medications may include:

• Quinidex (quinidine)
• Cordarone (amiodarone)
• Tambocor (flecainide)
• Rythmol (propafenone)

Antidepressants

Some antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants, interact with propranolol in various ways. Certain SSRIs can block liver enzymes and increase the levels of propranolol in the body, leading to increased side effects of propranolol. On the other hand, propranolol may increase certain side effects of tricyclic antidepressants, namely low blood pressure (postural hypotension).

Examples of SSRIs that interact with propranolol include:

• Prozac (fluoxetine)
• Paxil (paroxetine) 

Examples of tricyclic antidepressants include:

• Elavil (amitriptyline)
• Pamelor (nortriptyline)
• Tofranil (imipramine)

Migraine medications

Certain migraine medications, known as triptans, can interact with propranolol. Specifically, Maxalt (rizatriptan) and Zomig (zolmitriptan) can cause increased levels of propranolol in the body. In addition, propranolol can cause increased levels of these migraine medications. As a result, this interaction may cause increased side effects of both migraine medications and propranolol.  

• Maxalt (rizatriptan)
• Zomig (zolmitriptan)

Antimicrobial agents 

Several antimicrobial agents, including antivirals, antibiotics, and antifungal drugs, can disrupt the processing of propranolol. In many cases, the levels of propranolol may be increased, leading to potential side effects. However, certain antimicrobials, such as Rifadin (rifampin), can stimulate the metabolism of propranolol in the body, leading to decreased levels and reduced effectiveness of propranolol. Examples of antivirals that can interact with propranolol include:

• Rescriptor (delavudin)
• Norvir (ritonavir)

Examples of antibiotics include:

• Nydrazid (isoniazid)
• Rifadin (rifampin)

Examples of antifungals include:

• Diflucan (fluconazole)
• Sporanox (itraconazole)

Theo-24 (theophylline)

Theophylline, a medication used for asthma and chronic obstructive pulmonary disease (COPD), can be affected by propranolol. Taking theophylline and propranolol together may decrease theophylline levels, reducing the effectiveness of theophylline. In addition, theophylline may increase the levels of propranolol, leading to increased side effects of propranolol. 

Specific anticonvulsants

Certain anticonvulsants can stimulate the metabolism of propranolol, leading to reduced levels of propranolol in the body. Reduced blood levels may then lead to decreased effectiveness of the drug. Anticonvulsants that can interact with propranolol include:

• Dilantin (phenytoin)
• Tegretol (carbamazepine)

Antihypertensive medications

Propranolol can interact with other medications with blood pressure-lowering effects, including ACE inhibitors, calcium channel blockers, and alpha blockers. These drug interactions can intensify the effects of both propranolol and the antihypertensive, potentially leading to dangerously low blood pressure or slow heart rate (bradycardia). Symptoms of low blood pressure might also include lightheadedness and drowsiness. Examples of common beta blockers include:

• Catapres (clonidine)
• Lopressor, Toprol-XL (metoprolol tartrate, succinate)
• Vasotec (enalapril)
• Cozaar (losartan)
• Norvasc (amlodipine)
• Minipress (prazosin)

Nonsteroidal anti-inflammatory drugs (NSAIDs)

NSAIDs can weaken the blood pressure-lowering effects of beta blockers like propranolol. Combining propranolol with NSAIDs may lead to reduced effectiveness of propranolol in lowering blood pressure. Examples of NSAIDs include:

• Advil, Motrin (ibuprofen)
• Aleve (naproxen)
• Aspirin

Inotropic agents

Epinephrine is a drug used to treat severe allergic reactions and anaphylaxis. The interaction between propranolol and epinephrine can cause dangerously high blood pressure and an erratic heart rate. In addition, epinephrine may be less effective for anaphylaxis in people taking propranolol. Therefore, alternatives to epinephrine may be needed for anaphylaxis.

Coumadin (warfarin)

Warfarin is an anticoagulant or blood thinner commonly used to prevent blood clots. Propranolol has been shown to interact with warfarin, leading to increased anticoagulant levels. This interaction could increase the risk of bleeding, which may be life-threatening. Regular monitoring of bleeding is strongly advised when these drugs are taken together. 

Tagamet (cimetidine)

Cimetidine is a histamine H2 receptor blocker that can increase the levels of propranolol in the blood. This interaction can lead to increased side effects of propranolol, such as low blood pressure and a slow heart rate.

Discuss all medications you are taking, including over-the-counter drugs, with your healthcare provider to avoid potential interactions with propranolol. A healthcare provider can evaluate your medications and determine potential drug interactions. In many cases, the dose of propranolol may need to be adjusted, or medications changed entirely. 

This may not be a complete list of drug interactions.

Propranolol-food interactions

Propranolol may also interact with certain foods and beverages, which could lead to altered effectiveness of the drug or side effects.

Propranolol and high-fat meals

High-fat meals have been shown to affect the absorption of extended-release propranolol. Eating a high-fat meal could prolong how long it takes for extended-release propranolol capsules to reach maximum levels in the body. 

Propranolol and alcohol

It’s recommended to avoid drinking alcohol with propranolol. Alcohol can increase the levels of propranolol in the body, which could lead to increased side effects. 

Propranolol and caffeine

Caffeine can increase blood pressure, reducing the effectiveness of propranolol for lowering blood pressure. Avoiding excessive caffeine consumption if you have high blood pressure is recommended.

You may want to be aware of these food interactions while taking propranolol to maximize the drug’s efficacy and reduce potential side effects. Consult a healthcare professional if you have concerns about propranolol and food interactions. 

Other propranolol interactions

Propranolol may interact with other substances like dietary supplements, herbal remedies, and cigarette smoke. Propranolol may interact with substances such as:

• Calcium: Taking propranolol with calcium supplements, such as calcium citrate, carbonate, or gluconate, may lead to decreased effectiveness of propranolol. 
• Potassium: High potassium levels (hyperkalemia) are a rare but potentially serious side effect of propranolol. Taking propranolol with potassium supplements may increase the risk of hyperkalemia. 
• Vitamin E: Vitamin E may disrupt the absorption of propranolol, leading to decreased levels of propranolol in the body. 
• Smoking: Cigarette smoking has been shown to increase the elimination of propranolol from the body, leading to decreased levels of propranolol. As a result, smoking could decrease the effectiveness of the drug. 

Consult a healthcare provider about any supplements or vitamins you take before starting treatment with propranolol. Taking certain supplements or smoking cigarettes may require adjustments in the dosage of propranolol. 

Other considerations

While propranolol can be an effective medication, it may also be linked to health risks if you have certain medical problems. The use of propranolol may need to be modified in individuals with the following health conditions: 

• Kidney or liver disease: If you have kidney or liver problems, your body may have trouble processing propranolol. This could lead to elevated drug levels and increased side effects of propranolol.
• Heart conditions: Propranolol is a medication that can slow down heart rate. This drug may worsen your condition if you have a slow heart rate or heart failure.
• Asthma: People with asthma should use caution when taking propranolol. The drug may constrict airways, increasing the risk of severe bronchospasm or trouble breathing.
• Diabetes: Propranolol can mask the symptoms of low blood sugar (hypoglycemia), such as fast heart rate and shakiness. In addition, propranolol has been directly linked as a potential cause of hypoglycemia, especially after physical activity or in those with kidney problems. Sudden weight gain is a side effect that should be monitored while taking propranolol to manage diabetes effectively.
• Thyroid problems: Propranolol can also mask the symptoms of an overactive thyroid (hyperthyroidism). The medication may also cause changes in thyroid function lab tests. 

If you have a current medical history of medical conditions, consult your healthcare provider for medical advice before taking propranolol. 

How to minimize propranolol interactions

Propranolol is linked to several drug interactions, but taking the right steps can help minimize the risk of interactions and severe complications. One key way to minimize interactions is to keep a detailed list of all the medications and supplements you take.

A healthcare provider can adjust dosages, discontinue medications, and recommend alternatives if they find a risk for drug interactions with propranolol. They might also advise you on the medication’s half-life and the differences between the regular and extended-release versions of propranolol hydrochloride to avoid fluctuations in propranolol levels.

Ensure you take the correct dose according to your prescription and doctor’s instructions. In case of a missed dose, follow your healthcare provider’s advice on whether to take the missed dose or wait for the next scheduled dose. 

You may also want to be aware of the potential warning signs of drug interactions to recognize problems early on. Some common warning signs may include:

• Unexpected side effects
• New symptoms 
• Worsening of existing symptoms

Knowing the warning signs of drug interactions can help you quickly address problems before they become severe.

When to talk to a healthcare provider about propranolol interactions

Ideally, you’ll want to discuss drug interactions before you start treatment with any new medication. You should discuss propranolol interactions with a healthcare provider if you:

• Take any prescription or over-the-counter medications
• Use any dietary supplements or herbal products
• Have any medical conditions or a history of certain illnesses
• Experience any unexpected side effects or changes in health

Remember that this article does not cover an exhaustive list of propranolol interactions. Tell your healthcare provider about all medications, supplements, and medical conditions to reduce the risk of an interaction. By staying proactive and vigilant about potential propranolol interactions, you can ensure the best possible outcomes for your health.