Drug & supplement interaction

Yohimbe + Letrozole, Ribociclib Succinate

Letrozole, Ribociclib Succinate brand name: Kisqali Femara Co-Pack.

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

Letrozole, Ribociclib Succinate falls into 2 drug categories that Yohimbe can interact with; the most serious is rated moderate. Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of yohimbine, a constituent of yohimbe bark.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Yohimbe and Letrozole, Ribociclib Succinate

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Yohimbe interacts with whole categories of medication. Letrozole, Ribociclib Succinate falls into 2 of those categories, so it can interact with Yohimbe in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INHIBITORS

1 of 2

Why this applies to Letrozole, Ribociclib Succinate

Letrozole, Ribociclib Succinate falls under CYTOCHROME P450 3A4 (CYP3A4) INHIBITORS — the group Yohimbe interacts with.

Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of yohimbine, a constituent of yohimbe bark.
In vitro and clinical research shows that the yohimbe bark constituent, yohimbine, is metabolized by CYP3A4 enzymes. Theoretically, drugs that inhibit CYP3A4 might increase the levels and adverse effects of yohimbine.
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 thing to understand with your Kisqali plus Femara combo: ribociclib is a fairly strong blocker of an enzyme called CYP3A4, and that same enzyme happens to break down yohimbine, the active part of yohimbe bark. So if you took yohimbe while on ribociclib, the yohimbine could pile up in your body instead of clearing out normally.

What that might look like is an exaggerated version of yohimbe's own side effects, things like a racing heartbeat, spikes in blood pressure, anxiety, sweating, or trouble sleeping. I'll be honest, this is a theoretical concern based on how the enzyme works, not something proven in studies, so I'm not trying to alarm you. Still, with a cancer therapy like this, I'd run any yohimbe product past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Le Corre P, Parmer RJ, Kailasam MT, et al. Human sympathetic activation by alpha2-adrenergic blockade with yohimbine: Bimodal, epistatic influence of cytochrome P450-mediated drug metabolism. Clin Pharmacol Ther. 2004;76(2):139-53.
  2. Bharucha AE, Skaar T, Andrews CN, et al Relationship of cytochrome P450 pharmacogenetics to the effects of yohimbine on gastrointestinal transit and catecholamines in healthy subjects. Neurogastroenterol Motil. 2008;20(8):891-9. PubMed
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Letrozole, Ribociclib Succinate also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, yohimbe might decrease the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that yohimbe extract induces CYP3A4 enzymes.
Severity Minor 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

Your Kisqali Femara Co-Pack contains two active cancer medicines, letrozole and ribociclib, and both are cleared by a liver enzyme called CYP3A4. In lab dish studies, yohimbe appeared to speed up that enzyme. In theory, a faster enzyme could lower the levels of these drugs in your body, which might make your treatment work less well. Since these are important medicines for hormone-receptor-positive breast cancer, you really don't want anything quietly weakening them.

That said, this concern comes only from test-tube research, not from real patients, so it's far from proven. Still, because your therapy matters so much, I'd skip yohimbe unless your oncologist or pharmacist okays it. Please check with them before adding any supplement.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Haron MH, Dale O, Martin K, et al. Evaluation of the Herb-Drug Interaction Potential of Commonly Used Botanicals on the US Market with Regard to PXR- and AhR-Mediated Influences on CYP3A4 and CYP1A2. J Diet Suppl 2022. 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

Yohimbe Also Interacts With Other Medications

Yohimbe has 9 major, 679 moderate, 436 minor known drug interactions in our database — the Letrozole, Ribociclib Succinate one above is among them. If you take anything else, check it against the full list below.

Major 9 Moderate 679 Minor 436 No known interaction 1,706 (incl. Letrozole, Ribociclib Succinate)
Taking anything else?

Check Another of Your Medications Against Yohimbe

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

Everything else you take

See Every Supplement That Interacts With Letrozole, Ribociclib Succinate

This page covers Yohimbe only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Letrozole, Ribociclib Succinate page lists 155 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 109 moderate · 38 minor.

From our pharmacist’s overview on the Letrozole, Ribociclib Succinate page

“Grapefruit tops my worry list for anyone taking the Kisqali Femara Co-Pack (letrozole and ribociclib), because it blocks the enzyme, CYP3A4, that clears ribociclib and can push levels of this breast cancer drug higher than intended. That enzyme thread runs through 121 of the 155 ingredients on this page, and with eight rated major, rea…”

Reviewed by 2 · Jul 18, 2026

Open the Letrozole, Ribociclib Succinate interaction page

One more smart check

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

We hold 1,054 real supplement products containing Yohimbe, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Yohimbe. Your product may carry other ingredients that interact with Letrozole, Ribociclib Succinate too, on top of Yohimbe — 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 Yohimbe and Letrozole, Ribociclib Succinate 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 Yohimbe
Top 25%

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

29 days ago today
Medication Letrozole, Ribociclib Succinate
Top 25%

#411 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 Yohimbe

What is Yohimbe?

Yohimbe
  • Erectile dysfunction
  • Low sex drive
  • Sexual performance
  • Weight loss
  • Athletic performance

Yohimbe is a West African tree bark that contains yohimbine, a compound mainly promoted for erectile dysfunction and as an aphrodisiac. A prescription form of yohimbine has some evidence for erectile dysfunction, but over-the-counter yohimbe supplements vary widely in content and can cause serious side effects like high blood pressure and fast heart rate. Because of these safety concerns, talk to your pharmacist or doctor before using it.

Read the full Yohimbe monograph & all interactions
Keep checking

Other Drugs & Yohimbe

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

9Major
679Moderate
436Minor
1,705No known interaction
9 Major 679 Moderate 436 Minor 1,705 No interaction
Major

9 interactions

Moderate

679 interactions

Showing 60 of 679 moderate interactions — see all 679 on the Yohimbe page.

Minor

436 interactions

Showing 60 of 436 minor interactions — see all 436 on the Yohimbe page.

No interaction 1,705 drugs checked — show the list

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

Showing the 60 most looked-up of 1,705 medications checked with no known interaction — see the full Yohimbe list.

See the full Yohimbe interactions page
See every supplement checked against Letrozole, Ribociclib Succinate, 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
Yohimbe monograph › Uses, safety, and every drug interaction in one place Letrozole, Ribociclib Succinate supplement interactions › Every supplement checked against Letrozole, Ribociclib Succinate, 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 Yohimbe and Letrozole, Ribociclib Succinate Together: Common Questions

Can you take Yohimbe with Letrozole, Ribociclib Succinate?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Yohimbe and Letrozole, Ribociclib Succinate?
Letrozole, Ribociclib Succinate belongs to more than one drug category, and Yohimbe 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 Yohimbe and Letrozole, Ribociclib Succinate interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

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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.