Drug & supplement interaction

Blue-green Algae + Tacrolimus

Tacrolimus brand names: Prograf (capsule), Prograf (injectable), Protopic, Prograf XL, Astagraf XL, and others.

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

Blue-green Algae has a moderate interaction with Tacrolimus. Theoretically, concurrent use of blue-green algae might interfere with immunosuppressive therapy.

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

Blue-green Algae and Tacrolimus

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

Moderate

IMMUNOSUPPRESSANTS

Why this applies to Tacrolimus

Tacrolimus falls under IMMUNOSUPPRESSANTS — the group Blue-green Algae interacts with.

Theoretically, concurrent use of blue-green algae might interfere with immunosuppressive therapy.
Blue-green algae have been shown to stimulate the immune system.
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 thinking on this one. You take tacrolimus to quiet your immune system so your body doesn't attack your transplanted organ. Blue-green algae (like spirulina) work in the opposite direction. In lab studies, they appear to stimulate immune activity. So in theory, adding the algae could partly push against what your tacrolimus is doing, which is not what you want when you're protecting a transplant.

I want to be honest about the evidence here: this is based on test-tube and animal data, not real patients, so it's a theoretical concern rather than a proven one. But tacrolimus is a medication where we don't take chances. Please run any blue-green algae product past your transplant team or pharmacist before starting it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Jensen GS, Ginsberg DJ, Huerta P, et al. Consumption of Aphanizomenon flos-aquae has rapid effects on the circulation and function of immune cells in humans. A novel approach to nutritional mobilization of the immune system. JANA 2000;2:50-6.
  2. Hayashi O, Katoh T, Okuwaki Y. Enhancement of antibody production in mice by dietary Spirulina platensis. J Nutr Sci Vitaminol (Tokyo) 1994;40:431-41.. 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

Blue-green Algae Also Interacts With Other Medications

Blue-green Algae has 326 moderate known drug interactions in our database — the Tacrolimus one above is one of them. If you take anything else, check it against the full list below.

Moderate 326 No known interaction 2,504 (incl. Tacrolimus)
Taking anything else?

Check Another of Your Medications Against Blue-green Algae

Covers the 2,830 medications we’ve checked against Blue-green Algae. Pick one to open its full report.

From our Q&A

Questions About Blue-green Algae or Tacrolimus

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Blue-green Algae or Tacrolimus, 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 Tacrolimus

This page covers Blue-green Algae only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tacrolimus page lists 202 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Asarabacca (major) and Cesium (major).

By severity: 11 major · 152 moderate · 39 minor.

From our pharmacist’s overview on the Tacrolimus page

“Tacrolimus (Prograf, Astagraf XL, Envarsus XR) keeps a transplanted organ from being rejected, and it works inside a narrow blood-level window, meaning even small shifts can invite rejection or toxicity. That makes these 202 supplement interactions worth real caution.”

Reviewed by 2 · Jul 18, 2026

Open the Tacrolimus interaction page

One more smart check

Taking Blue-green Algae as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,180 real supplement products containing Blue-green Algae, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Blue-green Algae. Your product may carry other ingredients that interact with Tacrolimus too, on top of Blue-green Algae — 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 Blue-green Algae and Tacrolimus 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 Blue-green Algae
Top 10%

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

29 days ago today
Medication Tacrolimus
Top 25%

#398 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 Blue-green Algae

What is Blue-green Algae?

Blue-green Algae
  • General nutrition and energy
  • Antioxidant support
  • Cholesterol and metabolic health
  • Immune support
  • Weight management

Blue-green algae are nutrient-rich aquatic microorganisms (such as spirulina and Klamath Lake algae) taken as a supplement for energy, nutrition, and general wellness. Evidence for most health claims is limited, and some products can be contaminated with toxins or heavy metals, so quality testing matters. Talk to your pharmacist or doctor before using, especially during pregnancy or breastfeeding.

Read the full Blue-green Algae monograph & all interactions
Medication

About Tacrolimus

What Is Tacrolimus Used For?

Brand names: Prograf (capsule), Prograf (injectable), Protopic, Prograf XL, Astagraf XL, Envarsus XR

Tacrolimus is prescribed to help prevent your body from rejecting a transplanted organ. It is used in adults who receive a kidney, liver, or heart transplant, and in children who receive a liver transplant. It is always used alongside other anti-rejection medicines.

Because tacrolimus works by dampening your immune system, it lowers the risk of your body attacking the new organ — but it also means you need to be watched closely for infections and other side effects throughout your treatment.

See full Tacrolimus drug information
Keep checking

Other Drugs & Blue-green Algae

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

0Major
326Moderate
0Minor
2,503No known interaction
326 Moderate 2,503 No interaction
Moderate

326 interactions

Showing 60 of 326 moderate interactions — see all 326 on the Blue-green Algae page.

No interaction 2,503 drugs checked — show the list

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

Showing the 60 most looked-up of 2,503 medications checked with no known interaction — see the full Blue-green Algae list.

See the full Blue-green Algae interactions page
See every supplement checked against Tacrolimus, 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
Blue-green Algae monograph › Uses, safety, and every drug interaction in one place Tacrolimus supplement interactions › Every supplement checked against Tacrolimus, ranked by severity Tacrolimus 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 Blue-green Algae and Tacrolimus Together: Common Questions

Can you take Blue-green Algae with Tacrolimus?
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 Blue-green Algae and Tacrolimus 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 Tacrolimus and Blue-green Algae?

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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.