Drug & supplement interaction

Slippery Elm + Nitroglycerin

Nitroglycerin brand names: Nitrostat, Nitrogard SR, Sustachron, Nitro-Bid, Sustachron ER Buccal, and others.

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

Slippery Elm has a moderate interaction with Nitroglycerin. Theoretically, slippery elm may slow the absorption and reduce serum levels of oral drugs.

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

Slippery Elm and Nitroglycerin

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

Moderate

ORAL DRUGS

Why this applies to Nitroglycerin

Nitroglycerin falls under ORAL DRUGS — the group Slippery Elm interacts with.

Theoretically, slippery elm may slow the absorption and reduce serum levels of oral drugs.
Slippery elm inner bark contains mucilage, which may interfere with the absorption of orally administered drugs.
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 thing with slippery elm: it forms a thick, slippery gel in your stomach that can act like a barrier and slow down how well swallowed medicines get absorbed. So if you take an oral (swallowed) nitroglycerin product at the same time, the worry is that your body might take in a little less of it, which could make it less effective at preventing angina (chest pain).

A couple of important points. This is a theoretical concern based on how the fiber works, not something proven in studies, so don't panic. Also, many nitroglycerin forms (the under-the-tongue tablets, sprays, ointments, and patches) bypass the gut entirely, so this wouldn't apply to them. If you take a swallowed form, just separate the two by a few hours and check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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

Slippery Elm Also Interacts With Other Medications

Slippery Elm has 2,021 moderate known drug interactions in our database — the Nitroglycerin one above is one of them. If you take anything else, check it against the full list below.

Moderate 2,021 No known interaction 809 (incl. Nitroglycerin)
Taking anything else?

Check Another of Your Medications Against Slippery Elm

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

From our Q&A

Questions About Slippery Elm or Nitroglycerin

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

This page covers Slippery Elm only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nitroglycerin page lists 26 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Coleus (major), Hawthorn (major) and N-acetyl Cysteine (nac) (major).

By severity: 5 major · 11 moderate · 10 minor.

From our pharmacist’s overview on the Nitroglycerin page

“Nitroglycerin (Nitrostat, Nitro-Bid) exists to open blood vessels quickly during angina, so a supplement that also drops blood pressure, or one that fights the drug's effect, is not a small matter, and this list warrants real care before you add to it. The most serious entries pull in two directions.”

Reviewed by 2 · Jul 18, 2026

Open the Nitroglycerin interaction page

One more smart check

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

We hold 1,490 real supplement products containing Slippery Elm, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Slippery Elm. Your product may carry other ingredients that interact with Nitroglycerin too, on top of Slippery Elm — 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 Slippery Elm and Nitroglycerin 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 Slippery Elm
Top 10%

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

29 days ago today
Medication Nitroglycerin
Top 10%

#228 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 Slippery Elm

What is Slippery Elm?

Slippery Elm
  • Sore throat and cough
  • Heartburn and acid reflux
  • Digestive upset and IBS
  • Skin irritation (topical)
  • Constipation or diarrhea

Slippery elm is a traditional herbal remedy made from the inner bark of a North American elm tree, used mainly to soothe sore throats and irritated digestive tracts. Its mucilage can coat and calm mucous membranes, but solid human evidence for most uses is limited. It is generally considered low-risk for short-term use, but you should still check with your pharmacist or doctor first.

Read the full Slippery Elm monograph & all interactions
Medication

About Nitroglycerin Topical

What Is Nitroglycerin Topical Used For?

Brand names: Nitrostat, Nitrogard SR, Sustachron, Nitro-Bid, Sustachron ER Buccal, Nitroglyn, Nitro Time, Nitrong, Nitrogard, Nitrocine Timecaps, Nitroquick, Rectiv, Gonitro

Rectiv (nitroglycerin ointment 0.4%, applied rectally) is specifically indicated to treat moderate to severe pain associated with chronic anal fissure — a small tear in the lining of the anal canal.

Nitro-Bid (nitroglycerin ointment, applied to the skin) has been used to reduce exercise-related angina (chest pain brought on by physical activity). These are distinct products with separate uses; they are not interchangeable.

See full Nitroglycerin Topical drug information
Keep checking

Other Drugs & Slippery Elm

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

0Major
2,021Moderate
0Minor
808No known interaction
2,021 Moderate 808 No interaction
Moderate

2,021 interactions

Showing 60 of 2,021 moderate interactions — see all 2,021 on the Slippery Elm page.

No interaction 808 drugs checked — show the list

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

Showing the 60 most looked-up of 808 medications checked with no known interaction — see the full Slippery Elm list.

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

Can you take Slippery Elm with Nitroglycerin?
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 Slippery Elm and Nitroglycerin 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 Nitroglycerin and Slippery Elm?

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.