Herb & supplement monograph

Blue-green Algae Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Blue-green Algae interacts with medications. The heart of this page is the interaction list — every drug Blue-green Algae is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Blue-green Algae is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

Check Blue-green Algae against your medication

Add one medication

✓ Supplement

Blue-green Algae

1 Your medication

Start typing any prescription or over-the-counter drug name.

Reviewed by licensed pharmacists Sourced from Natural Medicines

On this page

Blue-green Algae Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Blue-green Algae drug interaction appears low for most people. None of the listed interactions are rated major, and the concerns that do exist rest mostly on theoretical reasoning or limited evidence rather than proven harm in people.

Interactions deserving the most attention

The best-supported concern involves diabetes medications: human research shows blue-green algae can lower blood sugar in people with diabetes, so adding it could increase the chance of blood sugar dropping too low. We also pay attention to immunosuppressants, because blue-green algae can stimulate the immune system and might, in theory, work against these closely-monitored medicines. Blood thinners appear on the list too, but a small human study found no effect on clotting, so a bleeding interaction is considered unlikely.

What the rest of the list means

The long list of medications comes from a few broad categories flagged at a moderate level, not hundreds of separately proven problems. Much of the concern is theoretical, and in at least one case, the predicted effect on blood clotting was tested in people and did not appear.

Check your medications against Blue-green Algae

Based on HelloPharmacist’s Blue-green Algae interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Blue-green Algae

327 medications have a known interaction with Blue-green Algae, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Blue-green Algae using our pharmacist-reviewed interaction data.

AI summaries are generated from our Blue-green Algae interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Blue-green Algae combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Blue-green Algae affects

Every type of medication (drug category) Blue-green Algae is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 3 drug categories Blue-green Algae interacts with

Anticoagulant/antiplatelet DrugsAntidiabetes DrugsImmunosuppressants

Anticoagulant/Antiplatelet Drugs

Theoretically, spirulina blue-green algae might increase the risk of bleeding if used with other anticoagulant or antiplatelet drugs. However, this is unlikely.
Spirulina blue-green algae have shown antiplatelet and anticoagulant effects in vitro. However, one preliminary study in 24 patients receiving spirulina blue-green algae 2.3 grams daily for 2 weeks showed no effect on platelet activation or measures of clotting time.

Likelihood Unlikely Evidence D

Antidiabetes Drugs

Theoretically, taking blue-green algae with antidiabetes drugs might increase the risk of hypoglycemia.
Human research shows that spirulina blue-green algae can have hypoglycemic effects in patients with diabetes, at least some of whom were using antidiabetes drugs. However, blue-green algae does not seem to improve glycated hemoglobin (HbA1c) levels in patients with diabetes. A meta-analysis of animal studies also suggests that spirulina blue-green algae have hypoglycemic effects.

Likelihood Possible Evidence B

Immunosuppressants

Theoretically, concurrent use of blue-green algae might interfere with immunosuppressive therapy.
Blue-green algae have been shown to stimulate the immune system.

Likelihood Possible Evidence D

Monograph

Blue-green Algae: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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.

Part used: Whole dried microorganism (algae biomass)
Common forms: Tablets, capsules, powder, flakes, and liquid extracts

People commonly use it for

General nutrition and energy
Antioxidant support
Cholesterol and metabolic health
Immune support
Weight management

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Quality varies and some products can be contaminated with toxins or heavy metals.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using. Some blue-green algae products, specifically those of the species Aphanizomenon flos-aquae,...

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using. Some blue-green algae products, specifically those of the species Aphanizomenon flos-aquae,...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Blue-green algae are tiny water-living organisms also called cyanobacteria. The term covers several different species. Two of the most common in supplements are spirulina (from the Arthrospira genus) and Aphanizomenon flos-aquae (often called Klamath algae, harvested from Klamath Lake in Oregon).

These algae grow in fresh and salt water around the world. They have been eaten for centuries in some cultures and are now sold as a "superfood" supplement. People take blue-green algae as tablets, capsules, powders, flakes, or liquids, often mixed into smoothies or other drinks.

Blue-green algae naturally contain protein and a mix of vitamins and minerals, which is part of why they are marketed for energy and general nutrition.

How it works

Blue-green algae contain protein, pigments like phycocyanin and chlorophyll, plant compounds, and a range of vitamins and minerals. Researchers believe some of these compounds may act as antioxidants, meaning they may help protect cells from a type of damage called oxidative stress.

Laboratory and animal studies suggest blue-green algae may affect inflammation, fat levels, and the immune system. However, these effects are not well proven in people, and results in a test tube or in animals do not always carry over to humans.

In short, the proposed mechanisms are mostly based on early research, and much remains uncertain.

Effectiveness

Does Blue-green Algae work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 37 uses evaluated

1 Possibly effective 36 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Hypertension