Drug & supplement interaction

Coleus + Amlodipine Besilate

Amlodipine Besilate brand name: Istin.

Major Interaction
Medically reviewed by · Updated September 2026
The bottom line Major

Amlodipine Besilate falls into 3 drug categories that Coleus can interact with; the most serious is rated major. Theoretically, combining coleus with calcium channel blockers might increase the coronary vasodilatory effects.

Read the full interaction report
SeverityMajor
LikelihoodProbable
Interactions3
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Coleus and Amlodipine Besilate

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Coleus interacts with whole categories of medication. Amlodipine Besilate falls into 3 of those categories, so it can interact with Coleus in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Major).

Major

CALCIUM CHANNEL BLOCKERS

1 of 3

Why this applies to Amlodipine Besilate

Amlodipine Besilate falls under CALCIUM CHANNEL BLOCKERS — the group Coleus interacts with.

Theoretically, combining coleus with calcium channel blockers might increase the coronary vasodilatory effects.
Forskolin, a constituent of coleus, and calcium channel blockers both cause coronary vasodilatory effects.
Severity Major Likelihood Probable Evidence B

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist: amlodipine (Istin) is a calcium channel blocker that relaxes and widens your blood vessels to lower blood pressure. Coleus contains forskolin, which can do something similar by raising a signaling molecule called cAMP and relaxing blood vessel walls. So when you put the two together, their blood-vessel-widening effects may stack up.

What might you actually notice? More of amlodipine's usual side effects, like dizziness or lightheadedness (especially when standing up), flushing, headache, or swollen ankles. Keep in mind this concern is largely theoretical and the evidence is limited. Still, since blood pressure is involved, it's worth a quick chat with your pharmacist or doctor before adding a Coleus supplement, rather than stopping anything on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Baumann G, Felix S, Sattelberger U, Klein G. Cardiovascular effects of forskolin (HL-362) in patients with idiopathic congestiv cardiomyopathy. A comparative study with dobutamine and sodium nitroprusside. J Cardiovasc Pharmacol 1990;16:93-100.
  2. Kramer W, Thormann J, Kindler M, Schlepper M. Effects of forskolin on left ventricular function in dilated cardiomyopathy. Arzneimittelforschung 1987;37:364-7.
Moderate

ANTIHYPERTENSIVE DRUGS

2 of 3

Amlodipine Besilate also falls under ANTIHYPERTENSIVE DRUGS.

Theoretically, combining coleus with antihypertensive drugs might cause additive blood pressure lowering effects and increase the risk of hypotension.
Animal research shows that forskolin, a constituent of coleus, may lower blood pressure.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Amlodipine (Istin) is a calcium channel blocker that lowers your blood pressure by relaxing and widening your blood vessels. Coleus contains forskolin, which in lab and animal studies also seems to relax blood vessels and nudge blood pressure down. So the concern here is simple: stacking the two could lower your pressure a little too much.

If that happened, you might feel dizzy or lightheaded, especially when standing up quickly, and you may notice more fatigue or even ankle swelling, which amlodipine can already cause. Keep in mind this interaction is theoretical, based mostly on animal research, so it is not a firm, proven effect. Still, if you take amlodipine and want to try Coleus, check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Baumann G, Felix S, Sattelberger U, Klein G. Cardiovascular effects of forskolin (HL-362) in patients with idiopathic congestiv cardiomyopathy. A comparative study with dobutamine and sodium nitroprusside. J Cardiovasc Pharmacol 1990;16:93-100.
  2. Kramer W, Thormann J, Kindler M, Schlepper M. Effects of forskolin on left ventricular function in dilated cardiomyopathy. Arzneimittelforschung 1987;37:364-7.
  3. Schlepper, M., Thormann, J., and Mitrovic, V. Cardiovascular effects of forskolin and phosphodiesterase-III inhibitors. Basic Res Cardiol 1989;84 Suppl 1:197-212. PubMed
  4. Lindner, E., Dohadwalla, A. N., and Bhattacharya, B. K. Positive inotropic and blood pressure lowering activity of a diterpene derivative isolated from Coleus forskohli: Forskolin. Arzneimittelforschung 1978;28(2):284-289.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

3 of 3

Amlodipine Besilate also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, taking coleus might decrease serum levels of drugs metabolized by CYP3A4.
In vitro research shows that coleus can activate the nuclear receptor, pregnane X receptor (PXR), which results in increased expression of CYP3A4. Although the clinical significance of this is not known, use caution when considering concomitant use of coleus and other drugs affected by these enzymes.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist of this one. Your body clears amlodipine using a liver enzyme called CYP3A4. Lab research hints that Coleus (forskolin) may rev up that enzyme, which could make your body break down amlodipine a little faster. If that happens, you might get a bit less benefit from the medication, meaning your blood pressure could creep up.

I want to be honest about how shaky this evidence is. It comes from test-tube and cell studies, not from real people, so we genuinely don't know if it matters in everyday life. Still, since amlodipine controls something as important as your blood pressure, it's worth a quick chat with your pharmacist or doctor before adding Coleus, especially if your readings have been borderline.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ding, X. and Staudinger, J. L. Induction of drug metabolism by forskolin: the role of the pregnane X receptor and the protein kinase a signal transduction pathway. J Pharmacol Exp Ther 2005;312(2):849-856. PubMed
  2. Staudinger, J. L., Ding, X., and Lichti, K. Pregnane X receptor and natural products: beyond drug-drug interactions. Expert.Opin Drug Metab Toxicol 2006;2(6):847-857. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Coleus Also Interacts With Other Medications

Coleus has 28 major, 886 moderate known drug interactions in our database — the Amlodipine Besilate one above is among them. If you take anything else, check it against the full list below.

Major 28 Moderate 886 No known interaction 1,916 (incl. Amlodipine Besilate)
Taking anything else?

Check Another of Your Medications Against Coleus

Covers the 2,830 medications we’ve checked against Coleus. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Amlodipine Besilate

This page covers Coleus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Amlodipine Besilate page lists 232 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Grapefruit (major) and St. John's Wort (major).

By severity: 7 major · 183 moderate · 42 minor.

From our pharmacist’s overview on the Amlodipine Besilate page

“People take amlodipine besilate (Istin) to lower blood pressure, then reach for fish oil, CBD, or a morning glass of grapefruit juice without a second thought, and this is a list that deserves genuine care. Seven of its 232 supplement interactions are rated major, with grapefruit the everyday standout because it blocks the enzyme (CYP3…”

Reviewed by 2 · Jul 18, 2026

Open the Amlodipine Besilate interaction page

One more smart check

Taking Coleus as Part of a Dietary Supplement Product? Check It for Interactions

We hold 803 real supplement products containing Coleus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Coleus. Your product may carry other ingredients that interact with Amlodipine Besilate too, on top of Coleus — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Coleus and Amlodipine Besilate Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Coleus
Top 25%

#233 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Amlodipine Besilate
Top 10%

#147 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Coleus

What is Coleus?

Coleus
  • Weight management
  • Asthma and breathing
  • High blood pressure
  • Heart conditions
  • Glaucoma (eye pressure)
  • Exercise and body composition

Coleus is a plant from the mint family whose root contains a compound called forskolin, often marketed for weight loss, asthma, and heart health. While early lab and small human studies are interesting, solid proof that Coleus supplements help any of these conditions is limited. Talk to your pharmacist or doctor before using it, especially if you have heart problems or low blood pressure.

Read the full Coleus monograph & all interactions
Keep checking

Other Drugs & Coleus

Browse every other medication we’ve checked against Coleus — both the ones with a known interaction and the ones without. Select any drug for the full detail.

28Major
886Moderate
0Minor
1,915No known interaction
28 Major 886 Moderate 1,915 No interaction
Major

28 interactions

Moderate

886 interactions

Showing 60 of 886 moderate interactions — see all 886 on the Coleus page.

No interaction 1,915 drugs checked — show the list

We also checked Coleus against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,915 medications checked with no known interaction — see the full Coleus list.

See the full Coleus interactions page
See every supplement checked against Amlodipine Besilate, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Coleus monograph › Uses, safety, and every drug interaction in one place Amlodipine Besilate supplement interactions › Every supplement checked against Amlodipine Besilate, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Coleus and Amlodipine Besilate Together: Common Questions

Can you take Coleus with Amlodipine Besilate?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Coleus and Amlodipine Besilate?
Amlodipine Besilate belongs to more than one drug category, and Coleus interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Coleus and Amlodipine Besilate interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Amlodipine Besilate and Coleus?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.