Angina and Hypertension Drug Amlodipine: Key Interactions With Other Drugs

Patients taking the widely prescribed once-daily, oral calcium channel blocker amlodipine (KATERZIA, NORLIQVA, NORVASC, SDAMLO and generics) should be aware that it has clinically important interactions with other medications and dietary supplements.[1]

Initially approved by the Food and Drug Administration in 1992, amlodipine is currently indicated for the treatment of high blood pressure (hypertension), chest pain (angina) and certain other types of coronary artery disease because it relaxes and widens blood vessels. The recommended starting dose of amlodipine in adults is 5 milligrams (mg), with a maximum recommended daily dose of 10 mg. Amlodipine is frequently available in combination with certain other hypertension medications.

Drugs that may increase amlodipine effects

Amlodipine is metabolized by liver enzymes, mainly the CYP3A4 enzyme, which breaks down the drug and helps in eliminating it from the body.[2] When taken at the same time as (or shortly before or after) amlodipine, oral drugs that inhibit the CYP3A4 enzyme also decrease the rate at which amlodipine is broken down, therefore increasing its levels in the blood.

Such an increase in blood levels of amlodipine may result in low blood pressure (hypotension) or edema (swelling). Therefore, reducing amlodipine’s dosage may be necessary when it is taken with any drug that can increase its levels.

For example, there is evidence that taking 5 mg of amlodipine concurrently with a 180-mg daily dose of the CYP3A4 inhibitor diltiazem (CARDIZEM, CARTIA XT, TIAZAC and generics) in older patients with hypertension results in a 60% increase in blood levels of amlodipine.

Although some drugs, such as sildenafil (VIAGRA, REVATIO, VYBRIQUE and generics), do not affect the metabolism of amlodipine, they have an additive blood-pressure-lowering effect because they also widen blood vessels.[3] Therefore, concurrent use of such drugs with amlodipine can be dangerous.

Table 1, below, provides examples of oral drugs that may increase amlodipine’s effects, including certain antibiotics, antifungal drugs and antiviral drugs for treating HIV infection.
 

Table 1. Examples of Oral Drugs That May Increase Amlodipine’s Effects[4],[5]

†Brand-name combination products were excluded.
*Designated as Limited Use by Worst Pills, Best Pills News
**Designated as Do Not Use except for serious fungal infection by Worst Pills, Best Pills News
***Designated as Do Not Use by Worst Pills, Best Pills News

Drugs that may decrease amlodipine effects

When taken concomitantly with amlodipine, certain oral drugs may enhance the activity of the CYP3A4 liver enzyme, which can, in turn, increase the rate at which amlodipine is broken down. This interaction can lead to decreased amlodipine levels in the blood and, therefore, inadequate treatment of angina and hypertension, potentially increasing the risk of heart attack or stroke.

Examples of these CYP3A4-stimulating drugs include certain antiseizure drugs, such as carbamazepine (CARBATROL, EPITOL, EQUETRO, TEGRETOL, TERIL and generics) and phenobarbital (generics only), as well as certain antibiotics, such as rifampin (RIMACTANE and generics) and rifapentine (PRIFTIN).

Also, kratom, an opioid-like plant substance available as a dietary supplement, can increase the CYP3A4 liver enzyme.

Drugs whose effects may be impacted by amlodipine

When taken concurrently with some drugs, amlodipine can affect their breakdown in the body. Examples of drugs whose effects may be increased by amlodipine are provided in Table 2, below.

For example, taking multiple 10-mg doses of amlodipine with 80 mg of the cholesterol-lowering drug simvastatin (FLOLIPID, ZOCOR and generics) can increase the blood levels of simvastatin by 77%. Such an increase in simvastatin levels raises the risk of myopathy (muscle damage, resulting in muscle pain and weakness) and rhabdomyolysis (a life-threatening, muscle-destroying condition that can lead to sudden kidney failure and death).

Likewise, a small prospective study in healthy volunteers with high CYP3A4 activity found that blood levels of the immunosuppressant drug tacrolimus (ASTAGRAF XL, ENVARSUS XR, PROGRAF and generics) increased more than twofold when taken concomitantly with amlodipine. A similar study in kidney transplant recipients showed that amlodipine increased blood levels of the immunosuppressant drug cyclosporine (GENGRAF, NEORAL, SANDIMMUNE and generics) by an average of at least 40%.

Importantly, concomitant use of amlodipine with dantrolene (DANTRIUM and generics), a drug used to treat malignant hyperthermia, a condition associated with a severe rise in blood pressure after surgery (due to sensitivity to general anesthesia medications), can cause high potassium levels (hyperkalemia). This interaction can lead to serious complications including irregular heart rhythm and cardiac arrest.

Table 2. Examples of Oral Drugs Whose Effects May Be Increased by Amlodipine[6],[7]

†Brand-name combination products were excluded.
*Designated as Limited Use by Worst Pills, Best Pills News
**Designated as Do Not Use by Worst Pills, Best Pills News

In contrast, the effects of some medications may be decreased by amlodipine. For instance, the antiplatelet effect of clopidogrel (PLAVIX and generics) may be decreased when it is taken concurrently with amlodipine. This can interfere with clopidogrel’s ability to prevent a heart attack or stroke.

What You Can Do

If you need treatment with amlodipine, review all your medications and dietary supplements with your clinician to assess for potentially significant interactions. If you are taking any medication that can interact with amlodipine, your clinician may adjust the dosage of amlodipine or the interacting drug and ask you to monitor your blood pressure more closely. Alternatively, your clinician may advise you to take a different drug to manage your cardiovascular condition. Never stop or change the dose of your medications without consulting your clinician first. Be aware that other drugs not listed in this article also may have dangerous interactions with amlodipine.
 

References

[1] Viatris. Label: amlodipine (NORVASC). February 2023. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=7367289c-b0b0-466a-83e2-558e2985c29f&type=display. Accessed June 3, 2026.

[2] Zhu Y, Wang F, Li Q, et al. Amlodipine metabolism in human liver microsomes and roles of CYP3A4/5 in the dihydropyridine dehydrogenation. Drug Metab Dispos. 2014;42(2):245-249.

[3] Viatris. Label sildenafil (VIAGRA). November 2023. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=d905dc8d-917f-4ea3-a4ee-a1ecf6967d4e&type=display. Accessed June 3, 2026

[4] IBM Micromedex. Drug interactions. http://www.micromedexsolutions.com/home/dispatch. Search term: “amlodipine.” Accessed June 3, 2026.

[5] Viatris. Label: amlodipine (NORVASC). February 2023. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=7367289c-b0b0-466a-83e2-558e2985c29f&type=display. Accessed June 3, 2026.

[6] IBM Micromedex. Drug interactions. http://www.micromedexsolutions.com/home/dispatch. Search term: “amlodipine.” Accessed June 4, 2026.

[7] Viatris. Label: amlodipine (NORVASC). February 2023. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=7367289c-b0b0-466a-83e2-558e2985c29f&type=display. Accessed June 4, 2026.