Drug & supplement interaction

Guar Gum + Isosorbide Dinitrate

Isosorbide Dinitrate brand names: Isordil, Angitak, Cedocard Retard, Isoket Retard, Isoket.

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

Guar Gum has a moderate interaction with Isosorbide Dinitrate. Guar gum might reduce the absorption of some oral drugs, potentially decreasing their effectiveness.

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

Guar Gum and Isosorbide Dinitrate

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

Moderate

ORAL DRUGS

Why this applies to Isosorbide Dinitrate

Isosorbide Dinitrate falls under ORAL DRUGS — the group Guar Gum interacts with.

Guar gum might reduce the absorption of some oral drugs, potentially decreasing their effectiveness.
Clinical research shows that guar gum reduces or slows absorption of medications such as penicillin and metformin. To avoid changes in absorption, take guar gum 30-60 minutes after oral medications.
Severity Moderate Likelihood Possible Evidence B

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 guar gum and your isosorbide dinitrate: this fiber forms a thick gel in your stomach that can grab onto pills and slow how much medicine actually gets absorbed. For a heart medicine you take to prevent chest pain, that could mean less of it reaches your bloodstream, so you might not get the steady angina protection you're counting on.

The good news is the fix is simple. Take your isosorbide first, then wait about 30 to 60 minutes before your guar gum. That spacing usually keeps things working as they should. This isn't a dangerous reaction, just a timing one, but since angina is nothing to gamble with, please run your routine by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gin H, Orgerie MB, Aubertin J. The influence of Guar gum on absorption of metformin from the gut in healthy volunteers. Horm Metab Res 1989;21:81-3.
  2. Huupponen R, Seppala P, Iisalo E. Effect of guar gum, a fibre preparation, on digoxin and penicillin absorption in man. Eur J Clin Pharmacol 1984;26:279-81. 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

Guar Gum Also Interacts With Other Medications

Guar Gum has 2,024 moderate known drug interactions in our database — the Isosorbide Dinitrate one above is one of them. If you take anything else, check it against the full list below.

Moderate 2,024 No known interaction 806 (incl. Isosorbide Dinitrate)
Taking anything else?

Check Another of Your Medications Against Guar Gum

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

From our Q&A

Questions About Guar Gum or Isosorbide Dinitrate

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

This page covers Guar Gum only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isosorbide Dinitrate page lists 22 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 Beer (moderate).

By severity: 4 major · 9 moderate · 9 minor.

From our pharmacist’s overview on the Isosorbide Dinitrate page

“Isosorbide dinitrate (Isordil, Isoket) relaxes blood vessels to prevent and relieve angina, so a supplement that pushes that relaxation further, or works against it, is not a small thing, and this list of 22 warrants genuine care. Four entries rate major: herbs with vasodilating effects of their own, like hawthorn, that can stack on to…”

Reviewed by 2 · Jul 18, 2026

Open the Isosorbide Dinitrate interaction page

One more smart check

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

We hold 33 real supplement products containing Guar Gum, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Guar Gum. Your product may carry other ingredients that interact with Isosorbide Dinitrate too, on top of Guar Gum — 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 Guar Gum and Isosorbide Dinitrate 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 Guar Gum
Top half

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

29 days ago today
Medication Isosorbide Dinitrate
Steady interest

#1,511 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 Guar Gum

What is Guar Gum?

Guar Gum
  • Constipation and bowel regularity
  • Diarrhea (as a stool bulking agent)
  • Lowering cholesterol
  • Blood sugar control
  • Feeling full for weight management

Guar gum is a soluble, gel-forming fiber from the guar bean that may modestly help with cholesterol, blood sugar, and bowel regularity. It is generally safe in food amounts, but concentrated supplements can cause gas, bloating, and a risk of throat or gut blockage if not taken with enough water. Always take it with plenty of fluid and check with your pharmacist or doctor first.

Read the full Guar Gum monograph & all interactions
Medication

About Isosorbide

What Is Isosorbide Used For?

Brand names: Isordil, Angitak, Cedocard Retard, Isoket Retard, Isoket

Isosorbide is used to prevent angina pectoris — chest pain or tightness caused by coronary artery disease. Both isosorbide dinitrate tablets and isosorbide mononitrate tablets (including Monoket and Isordil) are used for this purpose.

Important: none of these oral formulations work fast enough to stop a chest pain episode that has already started. They are taken on a schedule to prevent angina, not to treat it in the moment.

See full Isosorbide drug information
Keep checking

Other Drugs & Guar Gum

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

0Major
2,024Moderate
0Minor
805No known interaction
2,024 Moderate 805 No interaction
Moderate

2,024 interactions

Showing 60 of 2,024 moderate interactions — see all 2,024 on the Guar Gum page.

No interaction 805 drugs checked — show the list

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

Showing the 60 most looked-up of 805 medications checked with no known interaction — see the full Guar Gum list.

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

Can you take Guar Gum with Isosorbide Dinitrate?
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 Guar Gum and Isosorbide Dinitrate 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 Isosorbide Dinitrate and Guar Gum?

Our pharmacists answer your medication & supplement questions — free.

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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.