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

Chlorella 500 mg Ingredients & Drug Interactions

by NOW

Chlorella 500 mg label
See full label image
Tablet Or Pill Category: Botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Chlorella 500 mg 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

Chlorella 500 mg is a dietary supplement by NOW 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.

Jump to a section

Check Your Meds Against Chlorella 500 mg by NOW

Ask about any prescription or over-the-counter medication and we check it for interactions with Chlorella 500 mg by NOW — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of Chlorella 500 mg by NOW

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 Jul 11, 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 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: chlorella, a freshwater algae, at 500 mg per tablet. It also contains silicon dioxide as an inactive ingredient (a binder).

Chlorella is a whole-food supplement — the algae itself is the active material, not an isolated compound extracted from it.

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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: General nutrition and nutrient support.
  • We looked for evidence on: Pregnancy-related iron deficiency, Immune function, Antioxidant support, General wellness.
  • The strongest evidence on file: Chlorella is rated "Possibly Effective" for Pregnancy-related iron deficiency (Natural Medicines).

The evidence for chlorella is mixed. It's rated possibly effective for pregnancy-related iron deficiency.

For brain tumors, depression, fatigue, and nonalcoholic fatty liver disease (NAFLD), the evidence isn't strong enough to rate — we don't have reliable data yet to say whether it works for those.

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 in the short term, though product quality and purity vary widely depending on the brand and batch. The most common side effects are mild: allergic reactions, abdominal cramping, constipation, diarrhea, fatigue, gas, nausea, photosensitivity, and stool discoloration.

Most digestive upset happens during the first two weeks. Serious allergic reactions, including anaphylaxis, are rare but have been reported — in people taking it and in those preparing the tablets.

Because long-term safety data is limited, don't use chlorella unless your doctor approves it.

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.

Before taking Chlorella 500 mg, check with your pharmacist if you take warfarin or any other blood thinners — chlorella can reduce their effectiveness. Also flag any medications that make your skin photosensitive (sensitive to sunlight), because chlorella may add to that effect.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

Chlorella may be worth considering if you're pregnant with iron deficiency and your doctor recommends it. If you take warfarin or any photosensitizing medication, talk to your pharmacist before starting — this product can interfere with both.

Check your complete medication list with the tool on this page before you buy.

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

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jun 20, 2024.

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 Chlorella 500 mg, straight from the product label.

Brand NOW
Barcode (UPC) 733739026316
Net contents 200 Tablet(s)
Market status On market
Date entered into DSLD Jun 20, 2024
DSLD ID 313808
Product type Botanical
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Kosher, Organic, Gluten Free
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 Chlorella 500 mg by NOW, 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:
6 Tablet(s)
Maximum serving Sizes:
6 Tablet(s)
Servings per container
33
UPC/BARCODE
733739026316
IngredientAmount% DV
Calories10 Calorie(s)--
Total Carbohydrates1 Gram(s)1%
Protein2 Gram(s)--
Chlorella3 Gram(s)--

Other ingredients: Silicon Dioxide

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.
Suggested/Recommended/Usage/Directions

Suggested Use: Take 6 tablets daily.

Formula

NOW Chlorella delivers the natural nutrient profile found in genuine whole foods. Chlorella is a green single-celled microalgae that has naturally occurring chlorophyll, plus beta-carotene, mixed carotenoids, vitamin C, iron and protein. The cell wall in this high quality chlorella has been broken down mechanically to aid digestibility.

Naturally occurring chlorophyll & beta-carotene Broken cell wall algae

Triangle K (Kosher)

Formulation

Not manufactured with yeast, wheat, gluten, soy, corn, milk, egg, fish, shellfish, tree nut or sesame ingredients.

Natural color variation may occur in this product.

Super green

Vegetarian/Vegan

Non-GMO Project Verified nongmoproject.org

Certified Organic by QAI. US-ORG-050

Packaged and quality tested in the USA.

Precautions

Not manufactured with yeast, wheat, gluten, soy, corn, milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a facility that processes other ingredients containing these allergens.

Caution: May cause GI discomfort in sensitive individuals.

Storage

Store in a cool, dry place after opening.

Seals/Symbols

USDA Organic Triangle K (Kosher)

Non-GMO Project Verified nongmoproject.org

GMP Quality Assured

FDA Statement of Identity

A Dietary Supplement

General Statements

Botanicals/Herbs Family owned since 1968.

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

See for yourself

Chlorella 500 mg by NOW label

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

Chlorella 500 mg 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 Chlorella 500 mg by NOW

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

Serving size6 Tablet(s) Dosage formTablet Or Pill Servings per container33 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.

Protein

2 Gram(s) per serving

Chlorella

Interacts with
337 drugs
3 Gram(s) 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

Other (inactive) ingredients: Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Chlorella 500 mg by NOW Drug Interactions

Want to check YOUR meds against Chlorella 500 mg?

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 Chlorella 500 mg interact with 337 drugs. Click any drug to see the details.

1 of the 2 ingredients in Chlorella 500 mg interact with drugs. Each result below shows which ingredient is responsible. Chlorella

Each ingredient & the kinds of drugs it affects

For each ingredient in Chlorella 500 mg 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 Chlorella 500 mg, from the product label.

NOW

See all NOW products
Name
NOW FOODS
Street Address
395 S. Glen Ellyn Rd.
City
Bloomingdale
State
IL
ZipCode
60108
Web Address
www.nowfoods.com
Pharmacist Counseling Corner

Chlorella 500 mg by NOW: Common Questions

Does Chlorella 500 mg by NOW interact with any medications?
Yes. Based on its ingredients, Chlorella 500 mg 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?
Chlorella 500 mg 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 chlorella help with my energy?
Fatigue is on the list of uses people explore with chlorella, but we don't have reliable evidence that it works for that yet. The data isn't strong enough to say one way or the other.
Is chlorella safe if I'm pregnant?
The safety data on chlorella in pregnancy isn't established, so there isn't enough information to know either way. Talk with your doctor or pharmacist before taking it — they can weigh the potential benefits against the unknowns for your situation.
What's the most common side effect?
Stomach upset is most common, especially in the first two weeks: diarrhea, cramping, nausea, or gas. These are usually mild and tend to settle down. Rarely, some people have allergic reactions or photosensitivity.
Can chlorella cause a rash?
Chlorella can cause photosensitivity — sensitivity to sunlight that may lead to swelling or rash-like lesions on exposed skin. This was reported in five case histories. If you notice any reaction on sun-exposed areas after starting chlorella, tell your doctor or pharmacist right away.
Does the quality of chlorella supplements vary?
Yes — product quality and purity vary widely. Not all chlorella supplements are equal. Talk to your pharmacist about sourcing if you decide to use one.

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

Not sure if Chlorella 500 mg is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.

Chlorella 500 mg label
Go deeper

The Full Monographs Behind Chlorella 500 mg’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

Chlorella 500 mg'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

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team