Drug & supplement interaction

Caprylic Acid + Guanethidine Monosulfate

Guanethidine Monosulfate brand names: Ismelin, Isimil.

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

Caprylic Acid has a moderate interaction with Guanethidine Monosulfate. Theoretically, caprylic acid might increase the risk of hypotension when used with antihypertensive drugs.

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

Caprylic Acid and Guanethidine Monosulfate

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Guanethidine Monosulfate

Guanethidine Monosulfate falls under ANTIHYPERTENSIVE DRUGS — the group Caprylic Acid interacts with.

Theoretically, caprylic acid might increase the risk of hypotension when used with antihypertensive drugs.
Animal research suggests that caprylic acid might have positive inotropic effects, resulting in reduced arterial pressure and vascular resistance and increased cardiac output.
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

Guanethidine is an older, strong blood pressure medicine that works by lowering the activity of certain nerves, which relaxes blood vessels and brings pressure down. The concern here is simple: caprylic acid might also nudge blood pressure lower. If both push in the same direction, you could end up with too much of a drop.

What that can feel like with guanethidine is dizziness, lightheadedness, or even fainting, especially when you stand up quickly (this drug is already known for that). I want to be honest though, this interaction is theoretical and comes mostly from animal studies, so it may not happen at all. Food amounts of coconut oil are very unlikely to matter. Before starting a concentrated caprylic acid supplement, check with your doctor or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kristev A, Mitkov D, Lukanov Y, Chapkynov P. The effect of octanoic fatty acid on the cardiovascular system of the guinea pig. Cor Vasa 1989;31(4):321-7.

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

Caprylic Acid Also Interacts With Other Medications

Caprylic Acid has 261 moderate known drug interactions in our database — the Guanethidine Monosulfate one above is one of them. If you take anything else, check it against the full list below.

Moderate 261 No known interaction 2,569 (incl. Guanethidine Monosulfate)
Taking anything else?

Check Another of Your Medications Against Caprylic Acid

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

Everything else you take

See Every Supplement That Interacts With Guanethidine Monosulfate

This page covers Caprylic Acid only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Guanethidine Monosulfate page lists 137 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Tyramine (major) and Adrafinil (moderate).

By severity: 4 major · 112 moderate · 21 minor.

From our pharmacist’s overview on the Guanethidine Monosulfate page

“Guanethidine monosulfate (Ismelin) is a forceful older drug for severe high blood pressure, and its interaction list warrants genuine care. Nearly all 137 supplements and herbs on file pull blood pressure one way or the other, either adding to the drug's effect and risking dizziness and faints, or pushing pressure back up and undoing t…”

Reviewed by 2 · Jul 18, 2026

Open the Guanethidine Monosulfate interaction page

One more smart check

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

We hold 514 real supplement products containing Caprylic Acid, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Caprylic Acid. Your product may carry other ingredients that interact with Guanethidine Monosulfate too, on top of Caprylic Acid — 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 Caprylic Acid and Guanethidine Monosulfate 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 Caprylic Acid
Top 25%

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

29 days ago today
Medication Guanethidine Monosulfate
Steady interest

#1,449 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 Caprylic Acid

What is Caprylic Acid?

Caprylic Acid
  • Candida and yeast overgrowth
  • Gut health support
  • Antimicrobial
  • Digestive health
  • Part of ketogenic diets

Caprylic acid is a medium-chain fatty acid found in coconut oil and palm kernel oil that is popularly used for yeast overgrowth and gut health. While laboratory studies show it has antimicrobial activity, strong human evidence for most supplement claims is limited. It is generally considered safe in food amounts, but talk with your pharmacist or doctor before using concentrated supplements.

Read the full Caprylic Acid monograph & all interactions
Keep checking

Other Drugs & Caprylic Acid

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

0Major
261Moderate
0Minor
2,568No known interaction
261 Moderate 2,568 No interaction
Moderate

261 interactions

Showing 60 of 261 moderate interactions — see all 261 on the Caprylic Acid page.

No interaction 2,568 drugs checked — show the list

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

Showing the 60 most looked-up of 2,568 medications checked with no known interaction — see the full Caprylic Acid list.

See the full Caprylic Acid interactions page
See every supplement checked against Guanethidine Monosulfate, 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
Caprylic Acid monograph › Uses, safety, and every drug interaction in one place Guanethidine Monosulfate supplement interactions › Every supplement checked against Guanethidine Monosulfate, 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 Caprylic Acid and Guanethidine Monosulfate Together: Common Questions

Can you take Caprylic Acid with Guanethidine Monosulfate?
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 Caprylic Acid and Guanethidine Monosulfate 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 Guanethidine Monosulfate and Caprylic Acid?

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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.