Drug & supplement interaction

Wild Lettuce + Promethazine

Promethazine brand name: Phenergan.

Moderate Interaction
Medically reviewed by · Updated February 2023
The bottom line Moderate

Wild Lettuce has a moderate interaction with Promethazine. Studies report varying evidence on whether or not wild lettuce contains hyoscyamine, an anticholinergic drug.

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

Wild Lettuce 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 Wild Lettuce interacts with.

Studies report varying evidence on whether or not wild lettuce contains hyoscyamine, an anticholinergic drug. If it does, it appears to be in very low amounts. Nevertheless, there have been case reports of individuals consuming large amounts of wild lettuce experiencing anticholinergic-related side effects, such as constipation, dry mouth, dizziness, and sweating. Therefore, if you are already taking a drug with anticholinergic effects, you should be cautious about combining it with wild lettuce as the risk of side effects may be increased.
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 gist with Promethazine (Phenergan): it already has built-in anticholinergic activity, which is why it commonly causes dry mouth, constipation, blurry vision, drowsiness, and feeling a little foggy or dizzy. Wild lettuce might add a small anticholinergic push of its own, plus it's used as a calming, sedating herb, so the main concern is simply piling more of the same effects on top of each other.

I want to be honest about the evidence here: it's weak. It isn't even clear wild lettuce contains much anticholinergic compound, and the reports of trouble came from people taking large amounts. Still, since both can leave you extra sleepy and dried out, it's worth a quick chat with your pharmacist or doctor before pairing them, especially if you drive or are older.

Contact Dr. Brian directly if you have additional questions on this interaction

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

Wild Lettuce Also Interacts With Other Medications

Wild Lettuce has 392 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 392 No known interaction 2,438 (incl. Promethazine)
Taking anything else?

Check Another of Your Medications Against Wild Lettuce

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

From our Q&A

Questions About Wild Lettuce 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 Wild Lettuce 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 Wild Lettuce 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

One more smart check

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

We hold 99 real supplement products containing Wild Lettuce, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Wild Lettuce. Your product may carry other ingredients that interact with Promethazine too, on top of Wild Lettuce — 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 Wild Lettuce 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 Wild Lettuce
Steady interest

#1,150 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Promethazine
Top half

#1,056 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 Wild Lettuce

What is Wild Lettuce?

Wild Lettuce
  • Insomnia and trouble sleeping
  • Anxiety and restlessness
  • Pain relief
  • Cough and respiratory symptoms
  • Muscle spasms

Wild lettuce is a traditional herb used mainly for sleep, anxiety, and pain, but solid human research supporting these uses is very limited. Because its safety is not well studied, it should be used cautiously, avoided in pregnancy and breastfeeding, and discussed with your pharmacist or doctor first.

Read the full Wild Lettuce 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 & Wild Lettuce

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

0Major
392Moderate
0Minor
2,437No known interaction
392 Moderate 2,437 No interaction
Moderate

392 interactions

Showing 60 of 392 moderate interactions — see all 392 on the Wild Lettuce page.

No interaction 2,437 drugs checked — show the list

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

Showing the 60 most looked-up of 2,437 medications checked with no known interaction — see the full Wild Lettuce list.

See the full Wild Lettuce 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
Wild Lettuce 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 Wild Lettuce and Promethazine Together: Common Questions

Can you take Wild Lettuce 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 Wild Lettuce 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 Wild Lettuce?

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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.