Drug & supplement interaction

Syrian Rue + Carbidopa, Levodopa

Carbidopa, Levodopa brand names: Sinemet CR, Sinemet, Rytary, Dhivy.

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

Syrian Rue has a moderate interaction with Carbidopa, Levodopa. Theoretically, Syrian rue might increase the adverse effects of dopamine agonists.

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

Syrian Rue and Carbidopa, Levodopa

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

Moderate

DOPAMINE AGONISTS

Why this applies to Carbidopa, Levodopa

Carbidopa, Levodopa falls under DOPAMINE AGONISTS — the group Syrian Rue interacts with.

Theoretically, Syrian rue might increase the adverse effects of dopamine agonists.
Syrian rue contains the constituent harmine. Animal research shows that harmine increases extracellular dopamine levels. The clinical significance of this effect is unclear.
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 simple version: your Sinemet works by feeding your brain more dopamine, since levodopa is turned into dopamine once it gets there. Syrian Rue is thought to raise dopamine levels too, partly through a compound called harmine. So stacking the two could, in theory, push your dopamine signal higher than intended and amplify side effects you may already know, like nausea, dizziness when standing, a racing or pounding heart, vivid dreams, confusion, or extra involuntary movements (dyskinesias).

That said, this is only a theoretical concern based on animal data, not real human studies, so we honestly don't know how big a deal it is in people. Syrian Rue also carries its own toxicity risks. Please don't start it without checking with your doctor or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Iurlo, M., Leone, G., Schilstrom, B., Linner, L., Nomikos, G., Hertel, P., Silvestrini, B., and Svensson, H. Effects of harmine on dopamine output and metabolism in rat striatum: role of monoamine oxidase-A inhibition. Psychopharmacology (Berl) 2001;159(1 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

Syrian Rue Also Interacts With Other Medications

Syrian Rue has 1,121 moderate known drug interactions in our database — the Carbidopa, Levodopa one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,121 No known interaction 1,709 (incl. Carbidopa, Levodopa)
Taking anything else?

Check Another of Your Medications Against Syrian Rue

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

Everything else you take

See Every Supplement That Interacts With Carbidopa, Levodopa

This page covers Syrian Rue only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carbidopa, Levodopa page lists 43 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Branched-chain Amino Acids (bcaa) (major), Cowhage (major), Indian Snakeroot (major) and Magnesium (major).

By severity: 8 major · 24 moderate · 11 minor.

From our pharmacist’s overview on the Carbidopa, Levodopa page

“Carbidopa/levodopa (Sinemet, Rytary) anchors Parkinson's treatment, and because symptom control hinges on how much levodopa actually reaches the brain, the 43 supplements and herbs on this list deserve real respect before you add any of them. Eight carry a major rating, and almost all of the serious entries weaken the drug rather than…”

Reviewed by 2 · Jul 18, 2026

Open the Carbidopa, Levodopa interaction page

How much people look this up

Where Syrian Rue and Carbidopa, Levodopa 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 Syrian Rue
Steady interest

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

29 days ago today
Medication Carbidopa, Levodopa
Top 5%

#131 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 Syrian Rue

What is Syrian Rue?

  • Traditional remedy for digestive complaints
  • Used as a sedative or for mood
  • Antimicrobial and antiparasitic folk use
  • Used as a dye and incense
  • Recreational psychoactive use

Syrian Rue (Peganum harmala) is a traditional plant whose seeds contain potent compounds called harmala alkaloids, including MAO-inhibiting harmine and harmaline. There is little reliable human evidence that it safely treats any condition, and it carries real risks of toxicity, so it is not recommended for self-treatment. Talk to a pharmacist or doctor before considering it.

Read the full Syrian Rue monograph & all interactions
Medication

About Levodopa and Carbidopa

What Is Levodopa and Carbidopa Used For?

Brand names: Sinemet CR, Sinemet, Rytary, Dhivy

Levodopa and carbidopa is used to treat Parkinson's disease, post-encephalitic parkinsonism (parkinsonism that develops after a brain infection), and symptomatic parkinsonism that can follow carbon monoxide or manganese poisoning. These indications are shared across the oral tablet, orally disintegrating tablet, extended-release tablet, and extended-release capsule formulations (including Sinemet, Rytary, Crexont, and generic products).

DUOPA — a carbidopa/levodopa suspension given through a tube directly into the small intestine — is specifically indicated for the treatment of motor fluctuations in patients with advanced Parkinson's disease. This is a product-specific indication and does not apply to the oral forms.

See full Levodopa and Carbidopa drug information
Keep checking

Other Drugs & Syrian Rue

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

0Major
1,121Moderate
0Minor
1,708No known interaction
1,121 Moderate 1,708 No interaction
Moderate

1,121 interactions

Showing 60 of 1,121 moderate interactions — see all 1,121 on the Syrian Rue page.

No interaction 1,708 drugs checked — show the list

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

Showing the 60 most looked-up of 1,708 medications checked with no known interaction — see the full Syrian Rue list.

See the full Syrian Rue interactions page
See every supplement checked against Carbidopa, Levodopa, 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
Syrian Rue monograph › Uses, safety, and every drug interaction in one place Carbidopa, Levodopa supplement interactions › Every supplement checked against Carbidopa, Levodopa, ranked by severity Levodopa and Carbidopa 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 Syrian Rue and Carbidopa, Levodopa Together: Common Questions

Can you take Syrian Rue with Carbidopa, Levodopa?
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.
How serious is the Syrian Rue and Carbidopa, Levodopa 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

Still Have a Question About Carbidopa, Levodopa and Syrian Rue?

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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.