Interactions on record — worth a quick check against your medications. Based on 1 of 2 ingredients. Check your meds →
Dietary supplement

Spirulina & Chlorella Ingredients & Drug Interactions

by Onnit

Spirulina & Chlorella label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 30, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Spirulina & Chlorella against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Spirulina & Chlorella is a dietary supplement by Onnit with 2 active ingredients. Its ingredients are commonly taken for general nutrition and 'detox' support, immune support, liver and kidney support.Based on those ingredients, 337 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Chlorella. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Spirulina & Chlorella by Onnit

Ask about any prescription or over-the-counter medication and we check it for interactions with Spirulina & Chlorella by Onnit — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Spirulina & Chlorella by Onnit

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Sep 17, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains 2 active ingredients: chlorella and organic spirulina. Chlorella is a single-celled green alga, and spirulina is another type of algae — both are nutrient-dense whole foods used as dietary supplements.

The capsules also contain vegetarian capsule material, rice concentrate, and rice bran as inactive ingredients.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded Chlorella's overall clinical evidence instead.

Moderate

Some clinical evidence supports Chlorella for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Pregnancy-related iron deficiency — rated "Possibly Effective" (Natural Medicines).

Chlorella has possibly effective evidence for pregnancy-related iron deficiency. For brain tumors, depression, fatigue, and nonalcoholic fatty liver disease (NAFLD), the evidence is insufficient to rate — we don't yet know if it works for these uses.

We hold no effectiveness data for organic spirulina.

The evidence, ingredient by ingredient Chlorella

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Chlorella is generally well tolerated short term, but product quality and purity vary widely, so sourcing matters. Most common side effects are allergic reactions, abdominal cramping, constipation, diarrhea, fatigue, gas, nausea, photosensitivity, and stool discoloration — especially during the first two weeks.

Rare serious reactions like anaphylaxis have been reported. Safety hasn't been established for long-term use or in certain populations; your doctor should approve use if you have allergies or immune sensitivities.

For pregnancy, chlorella is rated possibly safe, but lactation safety data is not on file. Talk with your doctor or pharmacist before using it while breastfeeding.

Side effects, ingredient by ingredient Chlorella

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Chlorella.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 337 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check with your doctor or pharmacist before taking this product if you're on warfarin (Coumadin) or any blood thinner — chlorella may reduce how well it works. Also double-check if you take photosensitizing drugs, which increase sun sensitivity.

We could not check organic spirulina for interactions.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

Spirulina & Chlorella may interest you if you're looking for an algae-based nutrient supplement, especially if you have pregnancy-related iron deficiency — though the evidence for other uses is still uncertain. Avoid it if you take warfarin or photosensitizing drugs without first talking to your doctor or pharmacist, and be aware that allergic reactions and digestive upset can happen, particularly early on.

Because product quality varies, stick with a trusted brand source.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 23, 2023.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Spirulina & Chlorella, straight from the product label.

Brand Onnit
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Jan 23, 2023
DSLD ID 273163
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Women (not pregnant or lactating)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Spirulina & Chlorella by Onnit, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
2 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
7
IngredientAmount% DV
Chlorella500 mg--
organic Spirulina500 mg--

Other ingredients: Vegetarian Capsule, Rice concentrate, Rice Bran

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formulation

Complete Supplement Packs

FDA Statement of Identity

Dietary Supplement

General Statements

Go beyond a multivitamin Day Support Contains 1 Day Pack Not labeled for individual sale ONN

Suggested/Recommended/Usage/Directions

Suggested Use: Adults, as a dietary supplement, take one day packet in the morning or early afternoon, preferably with a light meal.

Precautions

Consult a medical doctor before taking this or any other nutritional supplement if you have or suspect a medical condition, or are taking any medications. Do not use if you are pregnant or nursing.

Keep out of reach of children.

Storage

Store in a cool, dry place.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Spirulina & Chlorella by Onnit label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Spirulina & Chlorella label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Spirulina & Chlorella by Onnit

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 Capsule(s) Dosage formCapsule Servings per container7 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Chlorella

Interacts with
337 drugs
500 mg per serving

Chlorella is a nutrient-rich freshwater green algae taken as a supplement for general wellness, immune support, and 'detox.' Some small studies sugges...

Chlorella monograph & interactions

Organic Spirulina

500 mg per serving

Other (inactive) ingredients: Vegetarian Capsule, Rice concentrate, Rice Bran. These complete the product’s ingredient list but are not active constituents.

Interaction report

Spirulina & Chlorella by Onnit Drug Interactions

Want to check YOUR meds against Spirulina & Chlorella?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
337Drugs
337 Moderate

Ingredients driving the most interactions

Chlorella 337

Individual Drug Interactions

The ingredients in Spirulina & Chlorella interact with 337 drugs. Click any drug to see the details.

1 of the 2 ingredients in Spirulina & Chlorella interact with drugs. Each result below shows which ingredient is responsible. Chlorella

Each ingredient & the kinds of drugs it affects

For each ingredient in Spirulina & Chlorella with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Chlorella2 drug types · 337 drugs

Photosensitizing Drugs

Theoretically, chlorella might have additive effects with photosensitizing drugs.
Chlorella has been reported to cause photosensitization. In five case reports, patients who had ingested chlorella exhibited swelling followed by erythematopurpuric lesions on sun-exposed areas of the body. Theoretically, concomitant use with photosensitizing drugs may exacerbate effects.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, chlorella might reduce the clinical effects of warfarin.
Chlorella contains significant amounts of vitamin K. There is at least one case report of warfarin therapy becoming sub-therapeutic after initiation of chlorella supplements.

Likelihood Possible Evidence D
Chlorella full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Spirulina & Chlorella, from the product label.

Onnit

See all Onnit products
Name
Onnit Labs
Pharmacist Counseling Corner

Spirulina & Chlorella by Onnit: Common Questions

Does Spirulina & Chlorella by Onnit interact with any medications?
Yes. Based on its ingredients, Spirulina & Chlorella has a known interaction with 337 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Spirulina & Chlorella contains 2 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Will this interact with my blood thinner?
If you take warfarin (Coumadin), yes — there's a documented interaction. Chlorella in this product contains vitamin K, which can reduce warfarin's effectiveness; one case report shows this happened when someone started chlorella. Check with your doctor or pharmacist before using this product.
What are the most common side effects?
Most people tolerate it well, but chlorella can cause abdominal cramping, constipation, diarrhea, gas, nausea, and stool discoloration — especially in the first two weeks. Allergic reactions and photosensitivity (sun-related skin reactions) have also been reported. Rare serious allergic reactions like anaphylaxis are possible.
Is it safe to take while pregnant?
Chlorella is rated possibly safe in pregnancy, but safety data for long-term use isn't complete. Talk with your doctor before starting it — they can weigh the benefits against any individual concerns.
Is it safe while breastfeeding?
We don't have lactation safety data on file for chlorella. Talk with your doctor or pharmacist for personalized advice before using this while breastfeeding.
Does this really work for fatigue or depression?
The evidence isn't there yet — we have insufficient reliable evidence to say whether chlorella works for fatigue or depression. It's possibly effective for pregnancy-related iron deficiency, but for other uses, the science is still being sorted out.
Why does the product quality vary?
Chlorella quality and purity vary widely between brands and suppliers. This matters because it affects both safety and effectiveness, so choosing a reputable, well-tested source is important.

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

Not sure if Spirulina & Chlorella is safe with your meds?

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Spirulina & Chlorella label
Go deeper

The Full Monographs Behind Spirulina & Chlorella’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Chlorella

Interacts with 337 drugs

Chlorella is a nutrient-rich freshwater green algae taken as a supplement for general wellness, immune support, and 'detox.' Some small studies suggest possible benefits for cholesterol, blo...

Read the full Chlorella monograph →
Sources

Sources & How We Checked

Spirulina & Chlorella's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 13 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Chlorella 13 references
  1. Peirce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York, NY: William Morrow and Co., 1999.
  2. Ng TP, Tan WC, Lee YK. Occupational asthma in a pharmacist induced by chlorella, a unicellular algae preparation. Resp Med 1994;88:555-7. PubMed
  3. Jitsukawa K, Suizu R, Hidano A. Chlorella photosensitization. New phytophotodermatosis. Int J Dermatol 1984;23:263-8. PubMed
  4. Merchant RE, Carmack CA, Wise CM. Nutritional supplementation with Chlorella pyrenoidosa for patients with fibromyalgia syndrome: a pilot study. Phytother Res 2000;14:167-73.
  5. Merchant RE, Rice CD, Young HF. Dietary Chlorella pyrenoidosa for patients with malignant glioma: effects on immunocompetence, quality of life, and survival. Phytother Res 1990;4:220-31.
  6. Halperin SA, Smith B, Nolan C, et al. Safety and immunoenhancing effect of a Chlorella-derived dietary supplement in healthy adults undergoing influenza vaccination: randomized, double-blind, placebo-controlled trial. CMAJ 2003;169:111-7..
  7. Ohtake, T., Negishi, K., Okamoto, K., Oka, M., Maesato, K., Moriya, H., and Kobayashi, S. Manganese-induced Parkinsonism in a patient undergoing maintenance hemodialysis. Am J Kidney Dis 2005;46(4):749-753. PubMed
  8. Ng, T. P., Tan, W. C., and Lee, Y. K. Occupational asthma in a pharmacist induced by Chlorella, a unicellular algae preparation. Respir.Med. 1994;88(7):555-557. PubMed
  9. Ohkawa, S., Yoneda, Y., Ohsumi, Y., and Tabuchi, M. [Warfarin therapy and chlorella]. Rinsho Shinkeigaku 1995;35(7):806-807.
  10. Azocar J, Diaz A. Efficacy and safety of chlorella supplementation in adults with chronic hepatitis C virus infection. World J Gastroenterol 2013;19(7):1085-90. PubMed
  11. Panahi Y, Badeli R, Karami GR, Badeli Z, Sahebkar A. A randomized controlled trial of 6-week Chlorella vulgaris supplementation in patients with major depressive disorder. Complement Ther Med 2015;23(4):598-602. PubMed
  12. Nakano S, Takekoshi H, Nakano M. Chlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant women. Plant Foods Hum Nutr 2010;65(1):25-30. PubMed
  13. Yavasoglu I, Turgutkaya A, Bolaman Z. Chlorella-induced thrombocytopenia. Sao Paulo Med J 2018;136(6):602-3. PubMed

See these in context on the Chlorella monograph →

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

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