Drug & supplement interaction

Hawthorn + Glyceryl trinitrate

Glyceryl trinitrate brand name: Nitronal.

Major Interaction
Medically reviewed by · Updated October 2026
The bottom line Major

Hawthorn has a major interaction with Glyceryl trinitrate. Theoretically, concomitant use might cause additive coronary vasodilatory effects.

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

Hawthorn and Glyceryl trinitrate

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

Major

NITRATES

Why this applies to Glyceryl trinitrate

Glyceryl trinitrate falls under NITRATES — the group Hawthorn interacts with.

Theoretically, concomitant use might cause additive coronary vasodilatory effects.
Some evidence shows that hawthorn might lower blood pressure due to vasodilatory effects.
Severity Major Likelihood Probable Evidence D

Interaction 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..

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

Here's the gist: nitroglycerin (Nitronal) works by relaxing and widening your blood vessels, which eases the heart's workload and relieves chest pain. Hawthorn seems to do something similar in a milder way, gently opening vessels and possibly nudging blood pressure down. Stack the two together and those effects can pile on top of each other.

What that might feel like is more lightheadedness, dizziness, a pounding headache, flushing, or feeling faint when you stand up, all signs your blood pressure has dipped too low. I'll be straight with you: this concern is based on how both work in theory and in lab studies, not on strong human trials, so it may not cause trouble for everyone. Still, since nitroglycerin already drops pressure noticeably, please check with your pharmacist or doctor before pairing it with hawthorn.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chang Q, Zuo Z, Harrison F, Chow MS. Hawthorn. J Clin Pharmacol 2002;42:605-12.
  2. Walker AF, Marakis G, Simpson E, et al. Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial. Br J Gen.Pract 2006;56:437-43.

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

Hawthorn Also Interacts With Other Medications

Hawthorn has 13 major, 177 moderate known drug interactions in our database — the Glyceryl trinitrate one above is one of them. If you take anything else, check it against the full list below.

Major 13 Moderate 177 No known interaction 2,640 (incl. Glyceryl trinitrate)
Taking anything else?

Check Another of Your Medications Against Hawthorn

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

From our Q&A

Questions About Hawthorn or Glyceryl trinitrate

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

This page covers Hawthorn only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Glyceryl trinitrate page lists 2 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Coleus (major).

By severity: 2 major.

From our pharmacist’s overview on the Glyceryl trinitrate page

“The irony with glyceryl trinitrate (Nitronal) is that both supplements known to interact with it, hawthorn and coleus, are sold for heart health, exactly the concern of someone using this angina medicine. Both interactions are rated major, and both work the same way.”

Reviewed by 2 · Jul 18, 2026

Open the Glyceryl trinitrate interaction page

One more smart check

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

We hold 2,624 real supplement products containing Hawthorn, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Hawthorn. Your product may carry other ingredients that interact with Glyceryl trinitrate too, on top of Hawthorn — 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 Hawthorn and Glyceryl trinitrate 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 Hawthorn
Top 10%

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

29 days ago today
Medication Glyceryl trinitrate
Steady interest

#2,712 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 Hawthorn

What is Hawthorn?

Hawthorn
  • Heart failure symptoms
  • High blood pressure
  • Chest pain (angina)
  • Irregular heartbeat
  • Digestive upset
  • Anxiety

Hawthorn is a plant traditionally used for heart-related complaints, and some studies suggest it may modestly help symptoms of mild heart failure when added to standard care. However, the evidence is mixed and it should never replace prescribed heart medicines. Always talk to your pharmacist or doctor before using hawthorn, especially if you have a heart condition.

Read the full Hawthorn monograph & all interactions
Keep checking

Other Drugs & Hawthorn

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

13Major
177Moderate
0Minor
2,639No known interaction
13 Major 177 Moderate 2,639 No interaction
Major

13 interactions

Moderate

177 interactions

Showing 60 of 177 moderate interactions — see all 177 on the Hawthorn page.

No interaction 2,639 drugs checked — show the list

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

Showing the 60 most looked-up of 2,639 medications checked with no known interaction — see the full Hawthorn list.

See the full Hawthorn interactions page
See every supplement checked against Glyceryl trinitrate, 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
Hawthorn monograph › Uses, safety, and every drug interaction in one place Glyceryl trinitrate supplement interactions › Every supplement checked against Glyceryl trinitrate, 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 Hawthorn and Glyceryl trinitrate Together: Common Questions

Can you take Hawthorn with Glyceryl trinitrate?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Hawthorn and Glyceryl trinitrate interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Glyceryl trinitrate and Hawthorn?

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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.