Drug & supplement interaction

Asafoetida + Guanethidine Monosulfate

Guanethidine Monosulfate brand names: Ismelin, Isimil.

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

Asafoetida has a moderate interaction with Guanethidine Monosulfate. Evidence from animal research suggests that asafoetida has hypotensive effects.

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

Asafoetida 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 Asafoetida interacts with.

Evidence from animal research suggests that asafoetida has hypotensive effects. Theoretically, concomitant use may increase therapeutic effects of antihypertensive therapy due to hypotensive activity of asafoetida. Some antihypertensive drugs include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others.
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, potent blood pressure medicine that lowers pressure by reducing the activity of certain nerves. Here's the thing to keep an eye on: lab and animal research hints that asafoetida itself may gently lower blood pressure too. So in theory, pairing concentrated asafoetida supplements with guanethidine could push your numbers down a little more than expected.

If that happens, you might feel dizzy, lightheaded, or faint, especially when standing up quickly. I want to stress this is a theoretical concern based on weak evidence, not something proven in people. The pinch of asafoetida in cooking is very unlikely to matter. If you're considering a concentrated supplement, check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Fatehi, M., Farifteh, F., and Fatehi-Hassanabad, Z. Antispasmodic and hypotensive effects of Ferula asafoetida gum extract. J Ethnopharmacol 2004;91(2-3):321-324. 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

Asafoetida Also Interacts With Other Medications

Asafoetida has 288 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 288 No known interaction 2,542 (incl. Guanethidine Monosulfate)
Taking anything else?

Check Another of Your Medications Against Asafoetida

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

Everything else you take

See Every Supplement That Interacts With Guanethidine Monosulfate

This page covers Asafoetida 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 Asafoetida as Part of a Dietary Supplement Product? Check It for Interactions

We hold 40 real supplement products containing Asafoetida, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Asafoetida. Your product may carry other ingredients that interact with Guanethidine Monosulfate too, on top of Asafoetida — 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 Asafoetida 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 Asafoetida
Top half

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

29 days ago today
Medication Guanethidine Monosulfate
Steady interest

#1,654 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 Asafoetida

What is Asafoetida?

Asafoetida
  • Digestive upset and gas
  • Bloating and stomach cramps
  • Irritable bowel symptoms
  • Respiratory complaints
  • Used as a cooking spice

Asafoetida is a strong-smelling plant resin used widely as a spice and in traditional medicine, mainly for digestive complaints. Solid human evidence for its medicinal benefits is limited, though it is generally considered safe in the small amounts used in cooking. Talk with your pharmacist or doctor before using concentrated supplements, and avoid them during pregnancy and breastfeeding.

Read the full Asafoetida monograph & all interactions
Keep checking

Other Drugs & Asafoetida

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

0Major
288Moderate
0Minor
2,541No known interaction
288 Moderate 2,541 No interaction
Moderate

288 interactions

Showing 60 of 288 moderate interactions — see all 288 on the Asafoetida page.

No interaction 2,541 drugs checked — show the list

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

Showing the 60 most looked-up of 2,541 medications checked with no known interaction — see the full Asafoetida list.

See the full Asafoetida 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
Asafoetida 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 Asafoetida and Guanethidine Monosulfate Together: Common Questions

Can you take Asafoetida 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 Asafoetida 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 Asafoetida?

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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.