Supplements and amlodipine: St. John's wort, grapefruit and what to ask

Short answer: Amlodipine (Norvasc) is taken once a day with or without food, and the drug-interactions section of its label names no vitamin or mineral. The herbal product to raise first is St. John's wort: the FDA lists it as a strong CYP3A inducer, and the Norvasc label says blood pressure should be closely monitored when amlodipine is taken with CYP3A inducers. The label reports that grapefruit juice had no impact on amlodipine levels, but a combination pill can bring its own grapefruit question. Do not stop or change amlodipine without talking to your doctor.

Amlodipine is in a class of medications called calcium channel blockers. MedlinePlus explains that it lowers blood pressure by relaxing the blood vessels so the heart does not have to pump as hard, and that it is also prescribed for certain types of chest pain (angina). For anyone adding a supplement, three things matter: the exact product you take, the herbs that can change how it is processed, and what your prescriber needs to see.

Check the exact product you take

MedlinePlus lists Norvasc, Katerzia and Norliqva as brand names, and amlodipine comes as a tablet, an oral solution and a suspension. Your prescription label is the place to start.

Amlodipine is also one half (or one third) of several combination pills. MedlinePlus lists these among them:

• Azor (amlodipine and olmesartan) and Tribenzor (amlodipine, olmesartan and hydrochlorothiazide)
• Exforge (amlodipine and valsartan) and Exforge HCT (amlodipine, valsartan and hydrochlorothiazide)
• Lotrel (amlodipine and benazepril)
• Caduet (amlodipine and atorvastatin)

The other drugs in these pills bring their own supplement questions. Olmesartan and valsartan are angiotensin II receptor antagonists (ARBs), and benazepril is an ACE inhibitor, so the potassium questions in our guide to lisinopril, losartan and potassium apply. Hydrochlorothiazide is a diuretic (water pill), covered in our guide to diuretics and supplements. Atorvastatin is a statin, covered in our guide to supplements and statins. If your label lists two or three drug names, read up on each one.

How amlodipine is taken, and why the label sets no supplement gap

MedlinePlus says to take amlodipine once a day with or without food, around the same time every day. The Norvasc prescribing information agrees: "The bioavailability of NORVASC is not altered by the presence of food." Its patient information suggests a regular time, "such as with breakfast or dinner, or at bedtime."

That is different from thyroid medicine, whose directions call for a four-hour gap from calcium, iron and multivitamins (see our levothyroxine timing guide). The Norvasc label sets no separation time for supplements. Its pharmacology section also reports: "Co-administered cimetidine, magnesium-and aluminum hydroxide antacids, sildenafil, and grapefruit juice have no impact on the exposure to amlodipine."

If you take amlodipine alongside a medicine that does have timing rules, such as levothyroxine, that other medicine's directions decide where your supplements go.

St. John's wort: the herb to raise first

The Norvasc label's drug-interactions section says: "No information is available on the quantitative effects of CYP3A inducers on amlodipine. Blood pressure should be closely monitored when amlodipine is co-administered with CYP3A inducers." The same section says drugs that block CYP3A raise the amount of amlodipine in the body, which shows this enzyme system matters for amlodipine. The FDA describes CYP3A4 as an enzyme that helps break down many drugs.

St. John's wort is on the FDA's own list. Its table of drug-interaction examples for healthcare professionals classifies St. John's wort as a strong CYP3A inducer, with the note that "the effect of St. John's wort varies widely and is preparation dependent."

NIH's National Center for Complementary and Integrative Health (NCCIH) puts it plainly: St. John's wort "can weaken the effects of many medicines." Its examples include certain statins, such as simvastatin, which matters if you take a statin alongside amlodipine. NCCIH asks anyone who takes any type of medicine to talk with their health care provider before using St. John's wort or other herbal products.

On a label, St. John's wort may also appear as hypericum or by its Latin name, Hypericum perforatum. NCCIH says it is most widely promoted for symptoms of depression and also for menopause symptoms, so read the full ingredient list of any blend sold for those purposes. If you already take it, tell your prescriber before you change anything.

Grapefruit: the answer depends on the pill

The FDA names nifedipine (Procardia, Adalat CC), another blood pressure drug, among the medicines grapefruit juice can affect. It also says grapefruit juice "does not affect all the drugs" in its examples, and amlodipine is a case in point: as quoted above, the Norvasc label reports that grapefruit juice had no impact on amlodipine exposure.

Combination pills are where this gets specific. Caduet contains atorvastatin, which the FDA names among the statins grapefruit can affect, and MedlinePlus's atorvastatin page says to talk to your doctor about eating grapefruit and drinking grapefruit juice. The FDA adds that the severity of a grapefruit interaction can differ by person, drug and amount, and that Seville oranges, pomelos and tangelos might have the same effect. Ask your pharmacist about your exact product rather than copying someone else's rule.

Calcium, magnesium and other vitamins and minerals

"Calcium channel blocker" describes how the drug works. The Norvasc label says amlodipine "inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle", the muscle cells of the blood vessels and the heart. The name is not an instruction about calcium in food or supplements.

The Norvasc drug-interactions section names no vitamin or mineral. The examples NIH's Office of Dietary Supplements (ODS) gives of medicines that interact with calcium supplements (dolutegravir, levothyroxine, lithium and quinolone antibiotics) don't include amlodipine either. ODS presents those as examples, not a complete list, so bring the product and the amount to your pharmacist.

The ODS magnesium fact sheet gives oral bisphosphonates and tetracycline and quinolone antibiotics as examples of medicines magnesium can interact with, and says some diuretics and proton pump inhibitors can affect magnesium status. If your combination pill includes hydrochlorothiazide, ODS notes that thiazide diuretics can increase the loss of magnesium in urine, one more reason to read the diuretics guide.

Other herbs worth a question

• Goldenseal. NCCIH says goldenseal "may change the way your body processes many medications."
• Licorice root. NCCIH says glycyrrhizin, a component of licorice root, can cause serious adverse effects, such as irregular heartbeat, especially in large amounts or over the long term, and that even small amounts from licorice root products have been linked to severe adverse effects in people who eat a lot of salt, have high blood pressure, or have heart or kidney conditions. NCCIH notes that products labeled deglycyrrhizinated licorice don't contain glycyrrhizin.

For every herbal product, NCCIH's advice is the same: if you take any type of medicine, talk with your health care provider first, because some herbs and medicines interact in harmful ways.

If you take a statin or another blood pressure medicine

The Norvasc label says to "limit the dose of simvastatin in patients on amlodipine to 20 mg daily." If a statin is on your list, our statins guide explains why niacin and red yeast rice belong in the same conversation.

The label also says amlodipine may be used alone or with other blood pressure medicines. If yours include metoprolol or carvedilol, see our guide to beta-blockers and supplements.

What to ask at your next refill

MedlinePlus says your blood pressure should be checked regularly to see how you respond to amlodipine, and the Norvasc patient information says: "Do not start any new prescription or non-prescription medicines or supplements, unless you check with your doctor first." Useful questions include:

• Is my pill amlodipine alone, or a combination? Which supplement questions come with each drug in it?
• Here are the labels of everything I take. Is St. John's wort, goldenseal, licorice or anything else on them a concern with my medicine?
• Does grapefruit matter for my exact product?
• If I take simvastatin too, is my dose within the limit the label sets with amlodipine?
• When is my next blood pressure check?

MedlinePlus suggests keeping a written list of all of the prescription and nonprescription medicines, vitamins, minerals and dietary supplements you take, and bringing it each time you visit a doctor. Our guide on how to check for duplicate supplement ingredients shows how to lay the labels side by side first.

Where VitOptics fits

VitOptics builds personalized daily supplement packs from a free, three-minute assessment. The assessment asks for your prescription medicines by name, along with your conditions and the supplements you already take, so amlodipine, or a combination pill that contains it, is part of the check from the start. Automated checks review the recommendation; some profiles need additional review by a person on our team. A second automated check reads the whole pack before release.

Your result lists every formula, the amount of each ingredient and the reason it is there, and it names one time of day for the whole pouch. Take it to your doctor or pharmacist and go over it alongside your prescription list before you start.

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Every VitOptics pack is checked against the medications you enter before anything goes in, and your result explains why each item is there.

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Sources

1. MedlinePlus: Amlodipine
2. DailyMed: Norvasc (amlodipine besylate) tablets, prescribing information and patient information
3. FDA: For Healthcare Professionals: FDA's Examples of Drugs that Interact with CYP Enzymes and Transporter Systems
4. FDA: Grapefruit Juice and Some Drugs Don't Mix
5. National Center for Complementary and Integrative Health: St. John's Wort
6. National Center for Complementary and Integrative Health: Goldenseal
7. National Center for Complementary and Integrative Health: Licorice Root
8. NIH Office of Dietary Supplements: Calcium Fact Sheet for Health Professionals
9. NIH Office of Dietary Supplements: Magnesium Fact Sheet for Health Professionals
10. MedlinePlus: Olmesartan
11. MedlinePlus: Valsartan
12. MedlinePlus: Benazepril
13. MedlinePlus: Hydrochlorothiazide
14. MedlinePlus: Atorvastatin

This article is for educational purposes and is not medical advice. Supplements are not intended to diagnose, treat, cure or prevent any disease.

Prepared with AI assistance using the sources linked in this article.

Last updated: October 23, 2026