What medicines should not be taken with amlodipine?

Amlodipine is a widely prescribed calcium channel blocker for high blood pressure and angina [1.2.2]. Knowing what medicines should not be taken with amlodipine is crucial, as some interactions can lead to dangerously low blood pressure or other severe side effects [1.3.1, 1.4.3].

Quick Summary

Amlodipine can interact with various drugs, including certain statins, antibiotics, antifungals, and immunosuppressants. These interactions can alter medication effectiveness or increase the risk of serious side effects.

Key Points

• Statins: Avoid taking more than 20mg of simvastatin or lovastatin with amlodipine due to an increased risk of muscle damage [1.3.2, 1.4.5].

• CYP3A4 Inhibitors: Certain antibiotics (clarithromycin) and antifungals (ketoconazole) can increase amlodipine levels, raising the risk of low blood pressure [1.3.1].

• CYP3A4 Inducers: Medications like rifampin and supplements like St. John's wort can make amlodipine less effective [1.3.2, 1.4.1].

• Immunosuppressants: Amlodipine can increase levels of drugs like cyclosporine and tacrolimus, requiring close monitoring [1.2.2, 1.3.1].

• Other Blood Pressure Drugs: Combining with beta-blockers or other antihypertensives can cause an additive effect, leading to excessively low blood pressure [1.2.2, 1.3.2].

• Grapefruit Juice: Consuming grapefruit can increase amlodipine concentrations in the blood, leading to more side effects [1.5.1].

• Consult Professionals: Always disclose all medications and supplements to your doctor to prevent dangerous interactions [1.3.1].

Amlodipine, sold under brand names like Norvasc, is a calcium channel blocker used to treat high blood pressure (hypertension), chest pain (angina), and coronary artery disease [1.2.2, 1.8.5]. It works by relaxing blood vessels, which allows blood to flow more easily [1.8.3]. While effective, amlodipine's metabolism in the body, primarily through the CYP3A4 enzyme, means it can interact with numerous other medications [1.3.1, 1.6.4]. These interactions can either increase amlodipine levels, leading to toxicity, or decrease its effectiveness. It's vital to be aware of which drugs, supplements, and even foods can cause these reactions.

Major Drug Interactions to Be Aware Of

Certain medications pose a significant risk when taken with amlodipine and may need to be avoided or require close monitoring and dose adjustments by a healthcare professional.

Certain Statins (Cholesterol Medications) One of the most critical interactions involves specific statins used to lower cholesterol. Amlodipine can increase the blood levels of simvastatin (Zocor) and lovastatin (Altoprev) [1.3.1, 1.4.5]. This happens because amlodipine is a weak inhibitor of the CYP3A4 enzyme, which is responsible for metabolizing these statins [1.6.3, 1.6.4].

• Risk: Increased statin levels can lead to a higher risk of muscle-related side effects, including myopathy (muscle pain and weakness) and, in rare cases, rhabdomyolysis, a severe condition of muscle breakdown that can cause kidney damage [1.2.2, 1.6.2].
• Management: The FDA recommends limiting the daily dose of simvastatin to 20mg when taken with amlodipine [1.3.5]. Doctors may also opt for alternative statins like pravastatin or rosuvastatin, which are not significantly metabolized by CYP3A4 and do not interact with amlodipine [1.6.4].

CYP3A4 Inhibitors and Inducers Amlodipine is broken down by the liver enzyme CYP3A4. Drugs that inhibit or induce this enzyme can significantly alter amlodipine's concentration in the body.

• Strong CYP3A4 Inhibitors: These drugs block the enzyme, leading to higher amlodipine levels and an increased risk of side effects like low blood pressure (hypotension) and swelling (edema) [1.3.1, 1.4.5]. Examples include:

  • Certain Antifungals: Ketoconazole, itraconazole (Sporanox), and fluconazole (Diflucan) [1.4.3].
  • Certain Antibiotics: Clarithromycin and erythromycin, especially in older adults, can cause dangerously low blood pressure and kidney problems [1.2.2, 1.3.3].
  • HIV Protease Inhibitors: Medications like ritonavir (Norvir) [1.3.1, 1.3.5].

• CYP3A4 Inducers: These drugs speed up the enzyme, reducing amlodipine levels and making it less effective [1.4.1]. Examples include:

  • Anticonvulsants: Carbamazepine, phenytoin, and phenobarbital [1.3.2].
  • Antibiotics: Rifampin [1.4.1].
  • Herbal Supplements: St. John's wort [1.3.2].

Moderate and Other Notable Interactions

Beyond the major interactions, several other drug classes warrant caution.

Other Blood Pressure Medications Combining amlodipine with other drugs that lower blood pressure can have an additive effect, potentially causing hypotension [1.3.2].

• Beta-Blockers: Drugs like metoprolol (Lopressor) or atenolol (Tenormin) can lead to very low blood pressure, especially in patients with certain heart conditions like aortic stenosis [1.2.2].
• Other Calcium Channel Blockers: Taking amlodipine with diltiazem or verapamil can increase the risk of side effects [1.3.2].

Immunosuppressants Amlodipine can increase the blood levels of certain immunosuppressants used to prevent organ transplant rejection.

• Affected Drugs: Cyclosporine (Neoral, Sandimmune), tacrolimus (Prograf), and sirolimus (Rapamune) [1.2.2, 1.3.1].
• Risk: Elevated levels of these drugs increase the risk of their associated side effects, such as kidney problems [1.3.5]. Close monitoring and dose adjustments of the immunosuppressant are necessary [1.7.5].

Erectile Dysfunction (ED) Medications PDE5 inhibitors also lower blood pressure. When combined with amlodipine, the risk of hypotension increases.

• Affected Drugs: Sildenafil (Viagra), tadalafil (Cialis), and avanafil (Stendra) [1.3.1].
• Management: Patients taking both may need to monitor their blood pressure closely, especially when starting the medication [1.2.2].

Comparison of Common Amlodipine Interactions

Interacting Drug Class	Examples	Potential Effect	Management Strategy
Certain Statins	Simvastatin, Lovastatin	Increased risk of muscle pain and damage (myopathy) [1.4.5]	Limit simvastatin dose to 20mg daily; consider alternative statins [1.3.5, 1.6.4]
CYP3A4 Inhibitors (Antifungals/Antibiotics)	Ketoconazole, Clarithromycin	Increased amlodipine levels, risk of low blood pressure and swelling [1.2.2, 1.3.1]	Dose adjustment of amlodipine; close monitoring [1.3.3]
CYP3A4 Inducers (Anticonvulsants)	Carbamazepine, Rifampin	Decreased amlodipine effectiveness [1.3.2, 1.4.1]	Dose adjustment of amlodipine may be needed; monitor blood pressure [1.2.2]
Immunosuppressants	Cyclosporine, Tacrolimus	Increased levels of the immunosuppressant, risk of toxicity [1.2.2, 1.3.5]	Frequent monitoring of immunosuppressant drug levels and dose adjustments [1.7.5]
Other Antihypertensives	Metoprolol (Beta-Blockers)	Additive blood pressure lowering, risk of severe hypotension [1.2.2]	Careful blood pressure monitoring, especially at initiation [1.2.2]
PDE5 Inhibitors	Sildenafil (Viagra)	Additive blood pressure lowering effect [1.3.1]	Monitor for dizziness and low blood pressure [1.2.2]

Food and Supplement Interactions

It's not just prescription drugs that can interact with amlodipine.

• Grapefruit: Consuming large amounts of grapefruit or grapefruit juice can inhibit the CYP3A4 enzyme, increasing the concentration of amlodipine in the blood and worsening side effects like dizziness or headaches [1.5.1, 1.4.1].
• St. John's Wort: This herbal supplement for depression can induce CYP3A4, potentially reducing amlodipine's effectiveness [1.3.2, 1.4.4].
• Alcohol: While there's no direct interaction, alcohol can enhance the blood pressure-lowering effect of amlodipine, potentially increasing dizziness and drowsiness [1.5.6].

Conclusion: Always Consult Your Healthcare Provider

Amlodipine is an effective medication, but its potential for interactions is significant. The lists provided here are not exhaustive [1.2.2]. Always inform your doctor and pharmacist about all medications, over-the-counter drugs, and herbal supplements you are taking [1.3.1]. Never start or stop any medication without consulting your healthcare provider. They can assess the risks, make necessary dose adjustments, or recommend safer alternatives to ensure your treatment is both effective and safe.

For more information, a good resource is the NHS page on amlodipine.

Frequently Asked Questions

What is the most common side effect of amlodipine?

The most common side effect of amlodipine is swelling (edema), particularly in the legs or ankles. Other common side effects include dizziness, flushing, and headache [1.8.1, 1.8.2].

Can I take ibuprofen (Advil) with amlodipine?

Regular, long-term use of NSAIDs like ibuprofen may counteract the blood pressure-lowering effects of amlodipine [1.4.1]. Occasional use is likely safe, but you should consult your doctor. Acetaminophen (Tylenol) is often a safer alternative for pain relief as it does not interact with amlodipine [1.3.6].

Is it safe to drink alcohol while taking amlodipine?

While there isn't a direct interaction, alcohol can add to the blood pressure-lowering effects of amlodipine, which may increase side effects like dizziness, drowsiness, and headaches. It is best to limit alcohol consumption [1.5.1, 1.5.6].

What happens if I take amlodipine with simvastatin?

Amlodipine increases the levels of simvastatin in your blood, which significantly raises the risk of muscle-related side effects, such as muscle pain, weakness (myopathy), and a rare but serious condition called rhabdomyolysis [1.2.2, 1.6.1]. The daily dose of simvastatin should not exceed 20mg when taken with amlodipine [1.3.5].

Can I take amlodipine with other blood pressure medicines?

Yes, amlodipine is often prescribed with other blood pressure medications. However, combining them can sometimes lower your blood pressure too much. Your doctor will monitor you closely and may need to adjust your dosages [1.3.2].

Should I avoid grapefruit juice with amlodipine?

Yes, it is generally recommended to avoid large amounts of grapefruit or grapefruit juice, as it can increase the levels of amlodipine in your body and worsen side effects like dizziness and headaches [1.5.1, 1.4.1].

What herbal supplements should be avoided with amlodipine?

St. John's wort should be avoided as it can decrease the effectiveness of amlodipine by speeding up its metabolism [1.3.2, 1.4.4]. Always talk to your doctor before taking any herbal supplements.