Drug & supplement interaction

Black Seed + Riociguat

Riociguat brand name: Adempas.

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

Black Seed has a moderate interaction with Riociguat. Theoretically, taking black seed with antihypertensive drugs might increase the risk of hypotension.

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

Black Seed 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 Black Seed interacts with.

Theoretically, taking black seed with antihypertensive drugs might increase the risk of hypotension.
Clinical research suggests that black seed powder and oil might reduce blood pressure by 2-3 mmHg. In animal research, black seed modestly reduces blood pressure and concomitant use of black seed and amlodipine (Norvasc) or metoprolol (Lopressor) increased the blood pressure lowering effects of these drugs.
Severity Moderate Likelihood Possible Evidence B

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 already works by relaxing your blood vessels to lower the pressure in your lungs, and as a side effect it can lower your overall blood pressure too. Black seed appears to gently nudge blood pressure down as well, by maybe 2 to 3 points in studies. Stack the two together and that combined drop could be a little stronger than expected.

What that might feel like is dizziness, lightheadedness, a headache, or feeling faint when you stand up. This concern is mostly theoretical and based on modest, lower-quality research, and a sprinkle of black seed as a spice in food is unlikely to matter. Concentrated supplement doses are the real question. Please check with your pharmacist or doctor before adding it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Dehkordi FR, Kamkhah AF. Antihypertensive effect of Nigella sativa seed extract in patients with mild hypertension. Fundam Clin Pharmacol 2008;22:447-52.
  2. Sahebkar A, Soranna D, Liu X, et al. A systematic review and meta-analysis of randomized controlled trials investigating the effects of supplementation with Nigella sativa (black seed) on blood pressure. J Hypertens 2016;34:2127-35. PubMed
  3. Alam MA, Bin Jardan YA, Raish M, Al-Mohizea AM, Ahad A, Al-Jenoobi FBI. Effect of Nigella sativa and fenugreek on the pharmacokinetics and pharmacodynamics of amlodipine in hypertensive rats. Curr Drug Metab. 2020;21(4):318-325. PubMed
  4. Bin Jardan YA, Ahad A, Raish M, Alam MA, Al-Mohizea AM, Al-Jenoobi FI. Effects of garden cress, fenugreek and black seed on the pharmacodynamics of metoprolol: an herb-drug interaction study in rats with hypertension. Pharm Biol 2021;59(1):1088-1097. 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

Black Seed Also Interacts With Other Medications

Black Seed has 911 moderate 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 911 No known interaction 1,919 (incl. Riociguat)
Taking anything else?

Check Another of Your Medications Against Black Seed

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

From our Q&A

Questions About Black Seed or Riociguat

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Black Seed or Riociguat, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Riociguat

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

We hold 226 real supplement products containing Black Seed, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Seed. Your product may carry other ingredients that interact with Riociguat too, on top of Black Seed — 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 Black Seed 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 Black Seed
Top 25%

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

29 days ago today
Medication Riociguat
Steady interest

#1,546 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 Black Seed

What is Black Seed?

Black Seed
  • Respiratory support (asthma, allergies, cough)
  • Digestive upset
  • Immune support
  • Blood sugar and cholesterol support
  • General inflammation

Black seed (Nigella sativa) is a traditional spice and remedy that has been studied for asthma, blood sugar, cholesterol, and blood pressure, with early research showing some promise but no firmly proven benefits. It is generally well tolerated in food amounts, but supplement-strength doses are less studied, so talk to your pharmacist or doctor before using it—especially if you are pregnant, breastfeeding, or take other medicines.

Read the full Black Seed monograph & all interactions
Medication

About Riociguat

What Is Riociguat Used For?

Brand name: Adempas

Riociguat tablets — sold under the brand names Adempas and Riociguat — are approved for adults with two types of high blood pressure in the lungs. The first is chronic thromboembolic pulmonary hypertension (CTEPH), a condition caused by blood clots that have blocked or narrowed the arteries in the lungs. Riociguat is used when surgery has not fully fixed the problem, or when surgery is not an option.

The second is pulmonary arterial hypertension (PAH), a progressive disease where the arteries in the lungs become stiff and narrowed. In PAH, riociguat helps improve exercise ability, functional class (how well you can get around day-to-day), and slows disease worsening. It can be used alone or combined with other PAH medicines called endothelin receptor antagonists or prostanoids.

See full Riociguat drug information
Keep checking

Other Drugs & Black Seed

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

0Major
911Moderate
0Minor
1,918No known interaction
911 Moderate 1,918 No interaction
Moderate

911 interactions

Showing 60 of 911 moderate interactions — see all 911 on the Black Seed page.

No interaction 1,918 drugs checked — show the list

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

Showing the 60 most looked-up of 1,918 medications checked with no known interaction — see the full Black Seed list.

See the full Black Seed 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
Black Seed 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 Black Seed and Riociguat Together: Common Questions

Can you take Black Seed 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 Black Seed 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

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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.