Drug & supplement interaction

Teazle + Promethazine

Promethazine brand name: Phenergan.

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

Teazle has a moderate interaction with Promethazine. In vitro research suggests that teazle extract can inhibit acetylcholinesterase activity.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Teazle and Promethazine

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

Moderate

ANTICHOLINERGIC DRUGS

Why this applies to Promethazine

Promethazine falls under ANTICHOLINERGIC DRUGS — the group Teazle interacts with.

In vitro research suggests that teazle extract can inhibit acetylcholinesterase activity. Theoretically, concurrent use of anticholinergic drugs and teazle might decrease the effectiveness of teazle or the anticholinergic agent.
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 is the simple version. Promethazine (Phenergan) works partly by blocking acetylcholine, one of your body's nerve signaling chemicals. That blocking action is what helps with nausea and allergy symptoms, but it also causes the familiar side effects like dry mouth, drowsiness, blurry vision, and constipation. Teazle is interesting because, in lab dish studies only, some of its compounds seem to do the opposite and boost acetylcholine a bit.

So in theory, the two could work against each other, meaning teazle might slightly dull how well promethazine controls your nausea or allergies, or vice versa. Keep in mind this is purely a theoretical, test-tube idea with no real human proof, so I would not lose sleep over it. Still, it is worth a quick mention to your pharmacist before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Oszmianski J, Wojdylo A, Juszczyk P, Nowicka P. Roots and leaf extracts of Dipsacus fullonum L. and their biological activities. Plants (Basel) 2020;9(1):78. 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

Teazle Also Interacts With Other Medications

Teazle has 218 moderate known drug interactions in our database — the Promethazine one above is one of them. If you take anything else, check it against the full list below.

Moderate 218 No known interaction 2,612 (incl. Promethazine)
Taking anything else?

Check Another of Your Medications Against Teazle

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

From our Q&A

Questions About Teazle or Promethazine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Teazle or Promethazine, 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 Promethazine

This page covers Teazle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Promethazine page lists 83 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 3 major · 57 moderate · 23 minor.

From our pharmacist’s overview on the Promethazine page

“Promethazine (Phenergan) is a phenothiazine antihistamine used for allergies, nausea, and motion sickness, and it is strongly anticholinergic on its own, causing dry mouth, blurred vision, drowsiness, and constipation. That is why the 83 supplements and herbs on this list deserve real attention, starting with the three rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Promethazine interaction page

How much people look this up

Where Teazle and Promethazine 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 Teazle
Steady interest

#1,099 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Promethazine
Steady interest

#2,002 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 Teazle

What is Teazle?

Teazle
  • Lyme disease (folk use)
  • Joint and muscle pain
  • Osteoarthritis and rheumatoid arthritis
  • Skin conditions such as psoriasis
  • Wound healing

Teazle (Dipsacus fullonum) is a spiky plant used in traditional and folk medicine, most notably as a tincture marketed for Lyme disease and for joint pain and skin problems. There is very little high-quality human research to support any of these uses, so its benefits remain unproven. Talk with a pharmacist or doctor before trying it, and never use it to replace standard treatment for serious infections like Lyme disease.

Read the full Teazle monograph & all interactions
Medication

About Promethazine

What Is Promethazine Used For?

Brand name: Phenergan

Promethazine is used for a wide range of conditions. Tablets, oral solution, and rectal suppositories (brands including Phenergan, Promethegan, and Phenadoz) are approved for seasonal and perennial allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, hives (urticaria), angioedema, dermographism, and allergic reactions to blood or plasma. They are also used for motion sickness (both prevention and active treatment), nausea and vomiting related to anesthesia and surgery, sedation, and as a helper medication alongside pain relievers after surgery.

Promethazine hydrochloride injection (brands including Phenergan and Promethazine HCl injection) is used for many of the same purposes but is reserved for situations where oral treatment is not possible — including allergic emergencies as an adjunct to epinephrine, sedation during labor, and as an aid during certain surgical procedures such as bronchoscopy and eye surgery.

See full Promethazine drug information
Keep checking

Other Drugs & Teazle

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

0Major
218Moderate
0Minor
2,611No known interaction
218 Moderate 2,611 No interaction
Moderate

218 interactions

Showing 60 of 218 moderate interactions — see all 218 on the Teazle page.

No interaction 2,611 drugs checked — show the list

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

Showing the 60 most looked-up of 2,611 medications checked with no known interaction — see the full Teazle list.

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

Can you take Teazle with Promethazine?
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 Teazle and Promethazine 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 Promethazine and Teazle?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.