Drug & supplement interaction

Brewer's Yeast + Selegiline

Selegiline brand names: Carbex, Eldepryl, Emsam, Zelapar.

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

Brewer's Yeast has a major interaction with Selegiline. Theoretically, taking brewer's yeast with MAOIs might increase the risk of hypertension.

Read the full interaction report
SeverityMajor
LikelihoodLikely
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Brewer's Yeast and Selegiline

Here is the interaction we found between these two, with the evidence behind it.

Major

MONOAMINE OXIDASE INHIBITORS (MAOIs)

Why this applies to Selegiline

Selegiline falls under MONOAMINE OXIDASE INHIBITORS (MAOIs) — the group Brewer's Yeast interacts with.

Theoretically, taking brewer's yeast with MAOIs might increase the risk of hypertension.
Brewer's yeast contains tyramine. Taking brewer's yeast with MAOIs might increase the risk for hypertensive crisis.
Severity Major Likelihood Likely Evidence D

Well-controlled human studies have demonstrated the likely existence of this interaction.

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

Here's the concern with this combo. Brewer's yeast naturally contains tyramine, and selegiline is an MAO-B inhibitor. Normally your body uses MAO enzymes to break down tyramine. When that breakdown is slowed, tyramine can pile up and trigger a sudden, dangerous spike in blood pressure (a hypertensive crisis), with symptoms like a pounding headache, racing heart, sweating, or chest tightness.

One reassuring point: at the lower doses used for Parkinson's, selegiline stays fairly selective for MAO-B, so the tyramine risk is lower than with older MAOIs. But at higher doses or with the Emsam patch, that selectivity fades. This caution is theoretical and based on pharmacology, not lots of real cases, but because the outcome can be serious, please ask your pharmacist or doctor before using brewer's yeast regularly.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.

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

Brewer's Yeast Also Interacts With Other Medications

Brewer's Yeast has 8 major, 87 moderate, 40 minor known drug interactions in our database — the Selegiline one above is one of them. If you take anything else, check it against the full list below.

Major 8 Moderate 87 Minor 40 No known interaction 2,695 (incl. Selegiline)
Taking anything else?

Check Another of Your Medications Against Brewer's Yeast

Covers the 2,830 medications we’ve checked against Brewer's Yeast. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Selegiline

This page covers Brewer's Yeast only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Selegiline page lists 102 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Bitter Orange (major), Cowhage (major) and Fever Bark (major).

By severity: 14 major · 75 moderate · 13 minor.

Open the Selegiline interaction page

One more smart check

Taking Brewer's Yeast as Part of a Dietary Supplement Product? Check It for Interactions

We hold 126 real supplement products containing Brewer's Yeast, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Brewer's Yeast. Your product may carry other ingredients that interact with Selegiline too, on top of Brewer's Yeast — 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 Brewer's Yeast and Selegiline 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 Brewer's Yeast
Top half

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

29 days ago today
Medication Selegiline
Steady interest

#2,235 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 Brewer's Yeast

What is Brewer's Yeast?

Brewer's Yeast
  • Source of B vitamins
  • Diarrhea (certain types)
  • Cold and flu support
  • Digestive health
  • Acne and skin health
  • Blood sugar support

Brewer's yeast is a nutrient-rich fungus that provides B vitamins, protein, and minerals, and a related yeast product (S. boulardii) is used for some types of diarrhea. Most other health claims have limited or weak evidence. It is generally well tolerated as a food or supplement, but talk to your pharmacist or doctor before using it regularly, especially if you have a weakened immune system.

Read the full Brewer's Yeast monograph & all interactions
Medication

About Selegiline

What Is Selegiline Used For?

Brand names: Carbex, Eldepryl, Emsam, Zelapar

Selegiline is used as an add-on treatment for people with Parkinson's disease who are already taking levodopa/carbidopa but are finding that the medication's effects are wearing off or becoming less reliable. It is not used alone — it only works as part of a combination approach.

In clinical studies, adding selegiline helped reduce the amount of daily levodopa needed, cut down on "off" time (periods when symptoms break through), and improved things like tremor, speech, movement, and overall daily function.

See full Selegiline drug information
Keep checking

Other Drugs & Brewer's Yeast

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

8Major
87Moderate
40Minor
2,694No known interaction
8 Major 87 Moderate 40 Minor 2,694 No interaction
Major

8 interactions

Moderate

87 interactions

Showing 60 of 87 moderate interactions — see all 87 on the Brewer's Yeast page.

Minor

40 interactions

No interaction 2,694 drugs checked — show the list

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

Showing the 60 most looked-up of 2,694 medications checked with no known interaction — see the full Brewer's Yeast list.

See the full Brewer's Yeast interactions page
See every supplement checked against Selegiline, 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
Brewer's Yeast monograph › Uses, safety, and every drug interaction in one place Selegiline supplement interactions › Every supplement checked against Selegiline, ranked by severity Selegiline drug information › The full plain-English guide to this medication 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 Brewer's Yeast and Selegiline Together: Common Questions

Can you take Brewer's Yeast with Selegiline?
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.
How serious is the Brewer's Yeast and Selegiline 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 Selegiline and Brewer's Yeast?

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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.