Drug & supplement interaction

Algal Oil + Riociguat

Riociguat brand name: Adempas.

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

Algal Oil has a moderate interaction with Riociguat. Theoretically, taking algal oil with antihypertensive drugs might increase the risk of hypotension.

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

Algal Oil and Riociguat

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Riociguat

Riociguat falls under ANTIHYPERTENSIVE DRUGS — the group Algal Oil interacts with.

Theoretically, taking algal oil with antihypertensive drugs might increase the risk of hypotension.
Algal oil usually contains docosahexaenoic acid (DHA) and/or eicosapentaenoic acid (EPA). There is evidence that fish oil, which also contains DHA and EPA, can modestly lower blood pressure and might have additive effects in patients treated with antihypertensive drugs.
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 simple version. Riociguat (Adempas) works by relaxing and widening your blood vessels, which naturally lowers blood pressure. Omega-3s from algal oil can gently nudge your blood pressure down too. So the worry here is that the two together could add up and drop your pressure a little more than expected.

If that happened, you might feel dizzy, lightheaded, or faint, especially when standing up quickly. The good news: this is a theoretical concern based on how these work, not something proven to cause big problems. Food amounts of omega-3s are unlikely to matter, but a concentrated daily supplement is worth a mention. Don't stop either one. Just let your pharmacist or doctor know so they can keep an eye on your readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Prisco D, Paniccia R, Bandinelli B, et al. Effect of medium-term supplementation with a moderate dose of n-3 polyunsaturated fatty acids on blood pressure in mild hypertensive patients. Thromb Res 1998;1:105-12.
  2. Toft I, Bonaa KH, Ingebretsen OC, et al. Effects of n-3 polyunsaturated fatty acids on glucose homeostasis and blood pressure in essential hypertension. A randomized, controlled trial. Ann Intern Med 1995;123:911-8.
  3. Sacks FM, Hebert P, Appel LJ, et al. Short report: the effect of fish oil on blood pressure and high-density lipoprotein-cholesterol levels in phase I of the trials of hypertension prevention. J Hypertens 1994;12:209-13.
  4. Vandongen R, Mori TA, Burke V, et al. Effects on blood pressure of omega 3 fats in subjects at increased risk of cardiovascular disease. Hypertension 1993;22:371-9. PubMed
  5. Mori, T. A., Bao, D. Q., Burke, V., Puddey, I. B., and Beilin, L. J. Docosahexaenoic acid but not eicosapentaenoic acid lowers ambulatory blood pressure and heart rate in humans. Hypertension 1999;34(2):253-260. PubMed
  6. Nestel, P., Shige, H., Pomeroy, S., Cehun, M., Abbey, M., and Raederstorff, D. The n-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid increase systemic arterial compliance in humans. Am.J.Clin.Nutr. 2002;76(2):326-330. PubMed
  7. Woodman, R. J., Mori, T. A., Burke, V., Puddey, I. B., Barden, A., Watts, G. F., and Beilin, L. J. Effects of purified eicosapentaenoic acid and docosahexaenoic acid on platelet, fibrinolytic and vascular function in hypertensive type 2 diabetic patients PubMed
  8. Theobald, H. E., Goodall, A. H., Sattar, N., Talbot, D. C., Chowienczyk, P. J., and Sanders, T. A. Low-dose docosahexaenoic acid lowers diastolic blood pressure in middle-aged men and women. J Nutr 2007;137(4):973-978.

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

Algal Oil Also Interacts With Other Medications

Algal Oil has 257 moderate, 117 minor known drug interactions in our database — the Riociguat one above is one of them. If you take anything else, check it against the full list below.

Moderate 257 Minor 117 No known interaction 2,456 (incl. Riociguat)
Taking anything else?

Check Another of Your Medications Against Algal Oil

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

Everything else you take

See Every Supplement That Interacts With Riociguat

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

We hold 188 real supplement products containing Algal Oil, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Algal Oil. Your product may carry other ingredients that interact with Riociguat too, on top of Algal Oil — 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 Algal Oil 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 Algal Oil
Top 25%

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

29 days ago today
Medication Riociguat
Steady interest

#2,178 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 Algal Oil

What is Algal Oil?

Algal Oil
  • Vegan/vegetarian source of omega-3s (DHA and EPA)
  • Heart and triglyceride health
  • Brain and eye support
  • Pregnancy and infant nutrition
  • General anti-inflammatory support

Algal oil is a plant-based source of the omega-3 fats DHA and (in some products) EPA, making it a popular alternative to fish oil for vegetarians, vegans, and people who dislike fish. There is reasonable evidence that omega-3s can lower triglycerides and support heart and brain health, though more research is needed for many specific uses. It is generally well tolerated, but check with your pharmacist or doctor before starting, especially if you take blood thinners or are pregnant.

Read the full Algal Oil 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.
See full Riociguat drug information
Keep checking

Other Drugs & Algal Oil

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

0Major
257Moderate
117Minor
2,455No known interaction
257 Moderate 117 Minor 2,455 No interaction
Moderate

257 interactions

Showing 60 of 257 moderate interactions — see all 257 on the Algal Oil page.

Minor

117 interactions

Showing 60 of 117 minor interactions — see all 117 on the Algal Oil page.

No interaction 2,455 drugs checked — show the list

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

Showing the 60 most looked-up of 2,455 medications checked with no known interaction — see the full Algal Oil list.

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

Can you take Algal Oil with Riociguat?
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 Algal Oil and Riociguat 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 Riociguat and Algal Oil?

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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.