Drug & supplement interaction

Canadian Hemp + Promethazine

Promethazine brand name: Phenergan.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Canadian Hemp and Promethazine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Canadian Hemp and Promethazine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Promethazine and Canadian Hemp in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Canadian Hemp safety at a glance

Canadian Hemp overall Avoid It contains toxic cardiac glycosides and is considered a poisonous plant, not a safe supplement.
Pregnancy Likely Unsafe When used orally due to the toxic potential of its cardiac glycoside constituents; avoid using. Read the full pregnancy detail
Breastfeeding Likely Unsafe When used orally due to the toxic potential of its cardiac glycoside constituents; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Promethazine and Canadian Hemp? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Promethazine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Promethazine is filed under 4 classifications — including phenothiazines, anticholinergic drugs, photosensitizing drugs. Canadian Hemp has documented interactions with 2 drug classes — the most serious being digoxin (lanoxin) (moderate) and diuretic drugs (moderate) — and none of Promethazine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Canadian Hemp Does Interact With Other Medications

Canadian Hemp has 76 moderate known drug interactions in our database — Promethazine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 76 No known interaction 2,754 (incl. Promethazine)
Taking anything else?

Check Another of Your Medications Against Canadian Hemp

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

What to actually watch for

No Interaction Found — But Data Suggests Canadian Hemp and Promethazine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • A slow heartbeat Worth acting on Additional detail

    Canadian Hemp

    “Orally, Canadian hemp can cause digitalis-like toxicity due to its cardiac glycoside constituents. Symptoms of toxicity can include bradycardia with hypotension, increased heart contractions, and reflex hypertension. Canadian hemp can also cause topical irritation of the gastrointestinal mucous membranes.”

    Canadian Hemp · Natural Medicines adverse-effect record, reported in hypertension.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    “Orally, Canadian hemp might cause bradycardia with low blood pressure, increased heart contractions, and reflex hypertension (18).”

    Canadian Hemp · Natural Medicines adverse-effect record, reported in hypertension.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Promethazine

    Listed in the ADVERSE REACTIONS section of the FDA label for Promethazine. Read the label on DailyMed ›

  • Vomiting / Nausea reported in 11.7% of FDA reports for Promethazine Additional detail

    Canadian Hemp

    “Orally, Canadian hemp can cause topical irritation of the gastrointestinal mucous membranes. This irritation can result in a higher incidence of nausea and vomiting than with other cardiac glycoside-containing plants (such as digitalis) (18).”

    Canadian Hemp · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Promethazine

    Listed in the ADVERSE REACTIONS section of the FDA label for Promethazine, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Canadian Hemp but not commonly for Promethazine: raised blood pressure and low blood pressure.

Effects for Promethazine come from the ADVERSE REACTIONS section of its FDA label; effects for Canadian Hemp come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 22,361 voluntary FDA FAERS reports for Promethazine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Canadian Hemp in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Unsafe

When used orally due to the toxic potential of its cardiac glycoside constituents; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Canadian Hemp 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 Canadian Hemp 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 Canadian Hemp 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 Canadian Hemp 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 Canadian Hemp
Top half

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

29 days ago today
Medication Promethazine
Top half

#1,219 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Canadian Hemp reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Canadian Hemp and Promethazine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Canadian Hemp

What is Canadian Hemp?

  • Heart-related swelling (dropsy/edema)
  • Fluid retention
  • Constipation
  • Urinary problems
  • Traditional folk remedy uses

Canadian Hemp (Apocynum cannabinum) is a toxic North American plant historically used as a heart stimulant and diuretic, but it contains potent cardiac glycosides that can cause dangerous heart and poisoning effects. It is not a safe or recommended dietary supplement, and there is no reliable modern evidence supporting its use. Avoid using it and talk to a pharmacist or doctor about safer, proven options.

Apocynum cannabinum · Apocynaceae · Dried roots and rhizomes · Tincture, dried root, traditional decoction (rarely sold as a modern supplement)

An interaction check asks whether these two react with each other — it does not ask whether Canadian Hemp is a good idea for someone in your situation. Here is what our Canadian Hemp record says about it on its own.

Canadian Hemp: dosing

There is no established safe dose for Canadian Hemp, and we do not provide one. Because it contains potent and potentially deadly heart-acting compounds with a very narrow safety margin, no general dosing guidance can be given.If you come across a product containing Apocynum cannabinum, do not take it without speaking to a pharmacist or doctor first. In nearly all cases, safer and better-studied options are available.

From our Canadian Hemp monograph — the full record covers uses, side effects and every documented interaction.

Read the full Canadian Hemp 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.

Most-Reported Side Effects for Promethazine

From FAERS, the FDA’s public side-effect reporting system (22,614 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dependence 3,586 reports
Nausea 2,646 reports
Vomiting 1,802 reports
Fatigue 1,496 reports
Diarrhea 1,341 reports
See full Promethazine drug information
Keep checking

Other Drugs & Canadian Hemp

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

0Major
76Moderate
0Minor
2,753No known interaction
76 Moderate 2,753 No interaction
Moderate

76 interactions

Showing 60 of 76 moderate interactions — see all 76 on the Canadian Hemp page.

No interaction 2,753 drugs checked — show the list

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

Showing the 60 most looked-up of 2,753 medications checked with no known interaction — see the full Canadian Hemp list.

See the full Canadian Hemp interactions page
See every supplement checked against Promethazine, ranked by severity
Evidence & sources

Canadian Hemp References

The 2 references that drive our Canadian Hemp monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Canadian Hemp and Promethazine Together: Common Questions

Is it safe to take Canadian Hemp with Promethazine?
We do not list a known interaction between Canadian Hemp and Promethazine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Canadian Hemp and Promethazine have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Canadian Hemp and Promethazine combination checked?
Interactions in our licensed database are recorded against drug classes. Promethazine is filed under 4 classifications, and Canadian Hemp has documented interactions with 2 drug classes — none of Promethazine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Canadian Hemp interact with any other medications?
Yes. Canadian Hemp has 76 documented drug interactions in our database — Promethazine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Promethazine interact with any supplements?
Yes. Promethazine has documented interactions with 83 supplements in our database — Canadian Hemp is not one of them. The Promethazine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Canadian Hemp monograph Uses, safety profile, and every drug interaction in one place Promethazine drug information The full plain-English guide to this medication Promethazine supplement interactions Every supplement checked against Promethazine, 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 References The 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Promethazine and Canadian Hemp?

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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.