Drug & supplement interaction

Ascophyllum Nodosum + Riociguat

Riociguat brand name: Adempas.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between Ascophyllum Nodosum and Riociguat in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Ascophyllum Nodosum and Riociguat

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Riociguat and Ascophyllum Nodosum in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Ascophyllum Nodosum safety at a glance

Ascophyllum Nodosu... overall Use caution Generally used in foods, but its iodine content and possible heavy metal contamination warrant caution.
Pregnancy Avoid Avoid due to high iodine levels and possible contaminants that may affect the baby.
Breastfeeding Avoid Avoid because iodine and contaminants can pass into breast milk.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Riociguat and Ascophyllum Nodosum? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Riociguat

Interactions in our licensed database are recorded against drug classes, not just single drug names. Riociguat is filed under 4 classifications — including antihypertensive drugs, p-glycoprotein substrates, cytochrome p450 3a4 (cyp3a4) substrates. Ascophyllum Nodosum has documented interactions with 3 drug classes — the most serious being amiodarone (cordarone) (moderate), antithyroid drugs (moderate) and thyroid hormone (moderate) — and none of Riociguat’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Ascophyllum Nodosum Does Interact With Other Medications

Ascophyllum Nodosum has 22 moderate known drug interactions in our database — Riociguat isn’t one of them. If you take anything else, check it against the full list below.

Moderate 22 No known interaction 2,808 (incl. Riociguat)
Taking anything else?

Check Another of Your Medications Against Ascophyllum Nodosum

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

What to actually watch for

What Riociguat’s Own FDA Label Lists

This is not an interaction — none of it involves Ascophyllum Nodosum. These are the most notable effects listed in the ADVERSE REACTIONS section of Riociguat’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 3 of them are worth acting on rather than waiting out — marked below.

  • Trouble swallowing Worth acting on
  • Anemia Worth acting on
  • Bleeding or bruising Worth acting on
  • Heartburn
  • Bloating or gas
  • A stuffy or runny nose
  • A fast or pounding heartbeat
  • Low blood pressure
  • Stomach upset
  • Constipation

Showing the 10 most notable of 16 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Riociguat. Read the label on DailyMed › Ascophyllum Nodosum’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Ascophyllum Nodosum side to compare — that is a limit of the record, not a statement that Ascophyllum Nodosum has no side effects.

Everything else you take

See Every Supplement That Interacts With Riociguat

This page covers Ascophyllum Nodosum only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Riociguat page lists 230 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), Grapefruit (major) and St. John's Wort (major).

By severity: 6 major · 187 moderate · 37 minor.

From our pharmacist’s overview on the Riociguat page

“Riociguat (Adempas) works by relaxing the blood vessels in your lungs, which also lowers blood pressure, so I read this list of 230 supplements and herbs with real concern, and the six rated major are what to understand first. Grapefruit can push riociguat levels up and intensify its effect, while St.”

Reviewed by 2 · Jul 18, 2026

Open the Riociguat interaction page

One more smart check

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

We hold 360 real supplement products containing Ascophyllum Nodosum, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ascophyllum Nodosum. Even though Ascophyllum Nodosum itself has no known interaction with Riociguat, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Ascophyllum Nodosum and Riociguat 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 Ascophyllum Nodosum
Top 25%

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

29 days ago today
Medication Riociguat
Steady interest

#1,603 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Ascophyllum Nodosum reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The Ascophyllum Nodosum and Riociguat records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Ascophyllum Nodosum

What is Ascophyllum Nodosum?

Ascophyllum Nodosum
  • Weight management
  • Blood sugar support
  • Thyroid support (iodine source)
  • Digestive health
  • Source of vitamins and minerals
  • Joint comfort

Ascophyllum nodosum (often sold as bladderwrack or brown seaweed) is a nutrient-rich algae that people use for weight, blood sugar, and thyroid support, but solid human evidence is limited for most of these uses. Because it naturally contains iodine and can absorb heavy metals like arsenic, it should be used cautiously, and pregnant or breastfeeding people should avoid it unless a doctor approves.

Ascophyllum nodosum · Fucaceae · Whole seaweed (thallus/fronds) · Capsules, tablets, powder, extracts, teas, and topical products

An interaction check asks whether these two react with each other — it does not ask whether Ascophyllum Nodosum is a good idea for someone in your situation. Here is what our Ascophyllum Nodosum record says about it on its own.

Ascophyllum Nodosum: dosing

There is no well-established standard dose of Ascophyllum nodosum. Products vary widely in strength and iodine content, which makes consistent dosing difficult.If you choose to use it, follow the directions on the product label and do not exceed the recommended amount.

From our Ascophyllum Nodosum monograph — the full record covers uses, side effects and every documented interaction.

Read the full Ascophyllum Nodosum monograph & all interactions
Medication

About Riociguat

What Is Riociguat Used For?

Brand name: Adempas

Riociguat — sold as Adempas and under the generic name Riociguat — is used to treat adults with two conditions that cause dangerously high blood pressure in the arteries of the lungs.

  • Chronic Thromboembolic Pulmonary Hypertension (CTEPH): Used after surgical treatment, or when surgery is not an option, to improve exercise capacity and functional class.
  • Pulmonary Arterial Hypertension (PAH): Used to improve exercise capacity, functional class, and to delay the condition from getting worse. It can be used alone or combined with certain other PAH medicines.

Most-Reported Side Effects for Riociguat

From FAERS, the FDA’s public side-effect reporting system (32,415 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 5,718 reports
Headache 4,513 reports
Nausea 3,769 reports
Diarrhea 3,533 reports
Dizziness 3,522 reports
See full Riociguat drug information
Keep checking

Other Drugs & Ascophyllum Nodosum

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

0Major
22Moderate
0Minor
2,807No known interaction
22 Moderate 2,807 No interaction
Moderate

22 interactions

No interaction 2,807 drugs checked — show the list

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

Showing the 60 most looked-up of 2,807 medications checked with no known interaction — see the full Ascophyllum Nodosum list.

See the full Ascophyllum Nodosum interactions page
See every supplement checked against Riociguat, ranked by severity
Evidence & sources

Ascophyllum Nodosum References

The 5 references that drive our Ascophyllum Nodosum monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  2. Sterling JB, Heymann WR. Potassium iodide in dermatology: a 19th century drug for the 21st century-uses, pharmacology, adverse effects, and contraindications. J Am Acad Dermatol 2000;43:691-7. PubMed
  3. Combet E, Ma ZF, Cousins F, et al. Low-level seaweed supplementation improves iodine status in iodine-insufficient women. Br J Nutr 2014;112:753-61. PubMed
  4. Simmons-Boyce JL, Purcell SL, Nelson CM, MacKinnon SL. Dietary Ascophyllum nodosum increases urinary excretion of tricarboxylic acid cycle intermediates in male Sprague-dawley rats. J Nutr 2009;139:1487-94. PubMed
  5. Sorge US, Henriksen M, Bastan A, et al. Short communication: Iodine concentrations in serum, milk, and tears after feeding Ascophyllum nodosum to dairy cows-A pilot study. J Dairy Sci 2016;99:8472-6. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Ascophyllum Nodosum and Riociguat Together: Common Questions

Is it safe to take Ascophyllum Nodosum with Riociguat?
We do not list a known interaction between Ascophyllum Nodosum and Riociguat. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Ascophyllum Nodosum and Riociguat combination checked?
Interactions in our licensed database are recorded against drug classes. Riociguat is filed under 4 classifications, and Ascophyllum Nodosum has documented interactions with 3 drug classes — none of Riociguat's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Ascophyllum Nodosum interact with any other medications?
Yes. Ascophyllum Nodosum has 22 documented drug interactions in our database — Riociguat is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Riociguat interact with any supplements?
Yes. Riociguat has documented interactions with 230 supplements in our database — Ascophyllum Nodosum is not one of them. The Riociguat interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Ascophyllum Nodosum monograph Uses, safety profile, and every drug interaction in one place Riociguat drug information The full plain-English guide to this medication Riociguat supplement interactions Every supplement checked against Riociguat, 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 References The 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Riociguat and Ascophyllum Nodosum?

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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.