Drug & supplement interaction

Forsythia + Azithromycin

Azithromycin brand names: Zithromax, Zmax, Azasite.

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

Forsythia has a minor interaction with Azithromycin. Theoretically, taking forsythia with azithromycin might increase the risk of adverse effects.

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

Forsythia and Azithromycin

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

Minor

AZITHROMYCIN (Zithromax)

Theoretically, taking forsythia with azithromycin might increase the risk of adverse effects. Animal research in rats shows that taking a single dose of forsythia with azithromycin decreases the clearance and increases the area under the curve of both forsythiaside, a constituent of forsythia, and azithromycin. The mechanism of this interaction is not well understood.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the gist: in one rat study, pairing forsythia with azithromycin slowed how fast the body cleared the antibiotic, which let a bit more of it linger in the bloodstream. Azithromycin isn't a prodrug, so it works as-is, and higher levels could in theory nudge up its usual side effects like nausea, stomach upset, or loose stools.

I want to be honest about how thin this is. It comes from animal research, not people, the experts rate it minor and unlikely, and the mechanism isn't really understood. So I wouldn't lose sleep over it. Still, since you're taking an antibiotic for a real infection, it's worth a quick mention to your pharmacist or doctor before adding a forsythia supplement, just so everyone's on the same page.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Li XG, Ni J, Shen S, Wang XP, Tian JC. Pharmacokinetic interaction of Forsythia suspensa extract and azithromycin injection after single and co-intravenous administration in rats. Chin J Nat Med 2020;18(3):234-240. 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

Forsythia Also Interacts With Other Medications

Forsythia has 122 moderate known drug interactions in our database — the Azithromycin one above is one of them. If you take anything else, check it against the full list below.

Moderate 122 No known interaction 2,708 (incl. Azithromycin)
Taking anything else?

Check Another of Your Medications Against Forsythia

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

From our Q&A

Questions About Forsythia or Azithromycin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Forsythia or Azithromycin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Azithromycin

This page covers Forsythia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Azithromycin page lists 92 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 · 71 moderate · 13 minor.

From our pharmacist’s overview on the Azithromycin page

“A five-day Z-Pak for a sinus or chest infection seems too brief to fuss over, but azithromycin (Zithromax, Zmax) deserves genuine caution around supplements, and the eight major-rated entries on this list are the ones to understand first. Most of those involve the heart.”

Reviewed by 2 · Jul 18, 2026

Open the Azithromycin interaction page

One more smart check

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

We hold 355 real supplement products containing Forsythia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Forsythia. Your product may carry other ingredients that interact with Azithromycin too, on top of Forsythia — 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 Forsythia and Azithromycin 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 Forsythia
Top 25%

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

29 days ago today
Medication Azithromycin
Top 5%

#60 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 Forsythia

What is Forsythia?

  • Colds and flu symptoms
  • Sore throat
  • Fever
  • Inflammation
  • Antimicrobial support

Forsythia is a traditional Chinese herb, used mainly for cold and flu symptoms and as part of multi-herb formulas. Most evidence comes from laboratory, animal, and traditional use rather than strong human studies, so its real-world benefits remain unproven. Talk to your pharmacist or doctor before using it, especially if you are pregnant, breastfeeding, or taking other medicines.

Read the full Forsythia monograph & all interactions
Medication

About Azithromycin

What Is Azithromycin Used For?

Brand names: Zithromax, Zmax, Azasite

  • Azithromycin is used to treat certain bacterial infections, such as bronchitis; pneumonia; sexually transmitted diseases (STD); and infections of the ears, lungs, sinuses, skin, throat, and reproductive organs. Azithromycin also is used to treat or prevent disseminated Mycobacterium avium complex (MAC) infection [a type of lung infection that often affects people with human immunodeficiency virus (HIV)]. Azithromycin is in a class of medications called macrolide antibiotics. It works by stopping the growth of bacteria.

  • Antibiotics such as azithromycin will not work for colds, flu, or other viral infections. Using antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.

See full Azithromycin drug information
Keep checking

Other Drugs & Forsythia

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

0Major
122Moderate
0Minor
2,707No known interaction
122 Moderate 2,707 No interaction
Moderate

122 interactions

Showing 60 of 122 moderate interactions — see all 122 on the Forsythia page.

No interaction 2,707 drugs checked — show the list

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

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Forsythia list.

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

Can you take Forsythia with Azithromycin?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Forsythia and Azithromycin interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Azithromycin and Forsythia?

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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.