Drug & supplement interaction

Syrian Rue + Phenylephrine, Tropicamide

Phenylephrine, Tropicamide brand name: Mydcombi.

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

Syrian Rue has a moderate interaction with Phenylephrine, Tropicamide. Theoretically, Syrian rue might decrease the effects of anticholinergic drugs.

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

Syrian Rue and Phenylephrine, Tropicamide

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

Moderate

ANTICHOLINERGIC DRUGS

Why this applies to Phenylephrine, Tropicamide

Phenylephrine, Tropicamide falls under ANTICHOLINERGIC DRUGS — the group Syrian Rue interacts with.

Theoretically, Syrian rue might decrease the effects of anticholinergic drugs.
Syrian rue contains harmine. Animal research suggests that intravenous administration of harmine potentiates the effects of acetylcholine or increases acetylcholine levels.
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

Mydcombi combines two eye drops, and the tropicamide part works by blocking acetylcholine (that's the anticholinergic action) to dilate your pupil and briefly relax the eye's focusing muscle. Syrian Rue's harmala alkaloids may nudge acetylcholine levels up, which is the opposite direction. In theory, that could work against tropicamide and make your pupils dilate a little less or wear off sooner.

Honestly, this is a very theoretical concern based only on animal studies, and these drops are used briefly in the eye, so a big effect is unlikely. Still, Syrian Rue carries its own real risks. Please check with your pharmacist or eye doctor before combining them, and don't change how you use your drops on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Slotkin, T. A. and DiStefano, V. Cardiovascular and respiratory effects of harmine. Proc Soc Exp Biol Med 1970;133(2):662-664. PubMed
  2. Javoy, F., Euvrard, C., Herbet, A., Bockaert, J., Enjalbert, A., Agid, Y., and Glowinski, J. Lack of involvement of dopaminergic and GABA neurones in the inhbitory effect of harmaline on the activity of striatal cholinergic neurones in the rat. Naunyn Sch

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 Phenylephrine, Tropicamide 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. Phenylephrine, Tropicamide)
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 Phenylephrine, Tropicamide

This page covers Syrian Rue only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine, Tropicamide page lists 34 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Henbane (major), Scopolia (major), Angel's Trumpet (moderate), Bacopa (moderate) and Belladonna (moderate).

By severity: 2 major · 29 moderate · 3 minor.

From our pharmacist’s overview on the Phenylephrine, Tropicamide page

“Mydcombi, the phenylephrine and tropicamide spray used to dilate pupils for eye exams, seems like a one-time thing, but enough of it reaches the bloodstream to matter, and the 34 supplement ingredients on this list call for real care before your appointment. Thirty of them act on tropicamide's anticholinergic side, either piling on its…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine, Tropicamide interaction page

How much people look this up

Where Syrian Rue and Phenylephrine, Tropicamide 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

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

29 days ago today
Medication Phenylephrine, Tropicamide
Top half

#1,103 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
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 Phenylephrine, Tropicamide, 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 Phenylephrine, Tropicamide supplement interactions › Every supplement checked against Phenylephrine, Tropicamide, 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 Syrian Rue and Phenylephrine, Tropicamide Together: Common Questions

Can you take Syrian Rue with Phenylephrine, Tropicamide?
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 Phenylephrine, Tropicamide 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.