Drug & supplement interaction

Dulse + Methenamine Mandelate

Methenamine Mandelate brand names: Mandelamine, Methimazole.

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

Dulse has a moderate interaction with Methenamine Mandelate. Theoretically, due to its iodine content, dulse might alter the effects of antithyroid drugs.

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

Dulse and Methenamine Mandelate

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

Moderate

ANTITHYROID DRUGS

Why this applies to Methenamine Mandelate

Methenamine Mandelate falls under ANTITHYROID DRUGS — the group Dulse interacts with.

Theoretically, due to its iodine content, dulse might alter the effects of antithyroid drugs.
Dulse is rich in iodine. Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history.
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 to know: the drug listed here (under the brand mix-up with Methimazole) is an antithyroid medicine that works by lowering how much thyroid hormone your body makes. Your thyroid uses iodine as the raw material to build that hormone. Dulse is a seaweed that's naturally loaded with iodine, so adding a concentrated dulse supplement could basically feed your thyroid extra fuel and work against what the medication is trying to do.

This concern is theoretical, based on how iodine behaves rather than firm studies, so don't panic. A sprinkle of dulse as food is unlikely to cause trouble, but high-dose iodine supplements can swing thyroid levels either way. Before adding dulse, please check with your pharmacist or doctor so your thyroid stays on track.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Allsopp P, Crowe W, Bahar B, et al. The effect of consuming Palmaria palmata-enriched bread on inflammatory markers, antioxidant status, lipid profile and thyroid function in a randomised placebo-controlled intervention trial in healthy adults. Eur J Nutr PubMed
  2. Takase T, Nakamura A, Miyoshi H, et al. Effects of Palmaria palmata on lipid metabolism and glycemic control in participants with hypercholesterolemia in a randomized double-blind placebo-controlled trial. Phytother Res. 2020.

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

Dulse Also Interacts With Other Medications

Dulse has 22 moderate, 62 minor known drug interactions in our database — the Methenamine Mandelate one above is one of them. If you take anything else, check it against the full list below.

Moderate 22 Minor 62 No known interaction 2,746 (incl. Methenamine Mandelate)
Taking anything else?

Check Another of Your Medications Against Dulse

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

Everything else you take

See Every Supplement That Interacts With Methenamine Mandelate

This page covers Dulse only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methenamine Mandelate page lists 91 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Ascophyllum Nodosum (moderate).

By severity: 4 major · 77 moderate · 10 minor.

From our pharmacist’s overview on the Methenamine Mandelate page

“People take methenamine mandelate (Mandelamine) day after day to keep urinary tract infections at bay, and that long habit is exactly why the 91 supplements on this page deserve genuine vigilance. Four carry a major rating, and most of those point at the liver: Siberian cocklebur has been linked to outright liver failure, and heavy bee…”

Reviewed by 2 · Jul 18, 2026

Open the Methenamine Mandelate interaction page

One more smart check

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

We hold 546 real supplement products containing Dulse, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Dulse. Your product may carry other ingredients that interact with Methenamine Mandelate too, on top of Dulse — 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 Dulse and Methenamine Mandelate 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 Dulse
Top 25%

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

29 days ago today
Medication Methenamine Mandelate
Top half

#1,345 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 Dulse

What is Dulse?

Dulse
  • Nutritional supplement (iodine, minerals)
  • Source of plant protein
  • General wellness
  • Anti-inflammatory support
  • Thyroid/iodine support

Dulse is a red seaweed eaten as a food in many coastal cultures and is a natural source of iodine, potassium, protein, and antioxidant compounds. As a food it is generally considered safe for most people, but concentrated supplements can deliver large amounts of iodine and potassium, so use caution. Talk to your pharmacist or doctor before using it medicinally, especially if you have thyroid or kidney problems.

Read the full Dulse monograph & all interactions
Medication

About Methimazole

What Is Methimazole Used For?

Brand names: Mandelamine, Methimazole

Methimazole tablets are used in adults and children with hyperthyroidism (an overactive thyroid) due to Graves' disease or toxic multinodular goiter when surgery or radioactive iodine is not the right option. They work to lower thyroid hormone levels and ease symptoms.

Methimazole tablets are also used to bring thyroid hormone levels down before a patient undergoes thyroidectomy (thyroid surgery) or radioactive iodine treatment, making those procedures safer.

See full Methimazole drug information
Keep checking

Other Drugs & Dulse

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

0Major
22Moderate
62Minor
2,745No known interaction
22 Moderate 62 Minor 2,745 No interaction
Moderate

22 interactions

Minor

62 interactions

Showing 60 of 62 minor interactions — see all 62 on the Dulse page.

No interaction 2,745 drugs checked — show the list

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

Showing the 60 most looked-up of 2,745 medications checked with no known interaction — see the full Dulse list.

See the full Dulse interactions page
See every supplement checked against Methenamine Mandelate, 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
Dulse monograph › Uses, safety, and every drug interaction in one place Methenamine Mandelate supplement interactions › Every supplement checked against Methenamine Mandelate, ranked by severity Methimazole 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 Dulse and Methenamine Mandelate Together: Common Questions

Can you take Dulse with Methenamine Mandelate?
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 Dulse and Methenamine Mandelate 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 Methenamine Mandelate and Dulse?

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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.