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 30, 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.

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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.

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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 Oct 1, 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.

NOW Chlorella 500 mg contains one active ingredient: chlorella, a freshwater microalgae. Each tablet delivers 500 mg of this whole-algae supplement.

The product also includes silicon dioxide as an inactive ingredient to help with tablet formation.

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).

The data shows chlorella is possibly effective for pregnancy-related iron deficiency. For other common uses — brain tumors, fatty liver disease, depression, and fatigue — the evidence we hold is insufficient to rate it.

That doesn't mean it doesn't work; it means the current research isn't strong enough yet to say either way.

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 between manufacturers. The most common side effects are allergic reactions, stomach cramping, constipation, diarrhea, fatigue, gas, nausea, photosensitivity, and darkened stool — many mild and temporary, especially in the first two weeks.

Rare but serious reactions include anaphylaxis (a severe allergic reaction). Long-term safety hasn't been established, so the data advises against taking it unless your doctor approves.

If you're pregnant, the data rates it as possibly safe, but there isn't enough information to know for certain — talk with your doctor or pharmacist about what's right for you.

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 NOW Chlorella 500 mg, check with your doctor or pharmacist if you take warfarin (Coumadin) or other blood thinners — chlorella's vitamin K content can reduce how well they work. Also check if you're on any photosensitizing medications that increase sun sensitivity, since 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 behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

Chlorella may be worth considering if you're pregnant and dealing with iron deficiency, or if your doctor has recommended it for another reason. If you take warfarin or any medication that increases sun sensitivity, you need to clear it first with your doctor or pharmacist — chlorella can interfere with both.

Start by checking your medications with the tool on this page, then have a conversation with your own healthcare provider before you begin.

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.
Can I take chlorella if I'm pregnant?
The data rates chlorella as possibly safe during pregnancy, but there isn't enough information to know for certain. Talk with your doctor or pharmacist about whether it's right for you, especially if you're looking to address pregnancy-related iron deficiency.
What are the most common side effects?
Most side effects are mild: stomach cramping, constipation, diarrhea, gas, nausea, and darkened stool, especially in the first two weeks. Allergic reactions can also occur. If you have a history of food or supplement allergies, mention it to your doctor or pharmacist before starting.
Why does chlorella interact with warfarin?
Chlorella is rich in vitamin K, which helps your blood clot. Warfarin works by blocking vitamin K's effects to thin your blood. When you add chlorella, the extra vitamin K can work against the warfarin and make it less effective, so your blood may clot more easily than it should.
What is chlorella, and what is it supposed to do?
Chlorella is a freshwater microalgae — a single-celled green plant. It's used as a nutritional supplement and may help with pregnancy-related iron deficiency, though the evidence for other uses like fatigue or liver health isn't strong enough to rate yet.
Can chlorella cause sun sensitivity?
Yes. Chlorella has been reported to cause photosensitization in some people — meaning it can make your skin more sensitive to sun exposure, leading to swelling or red or purple lesions on areas exposed to the sun. If you're already on a medication that increases sun sensitivity, this risk may be higher.
Is there any other ingredient I should know about?
The tablet also contains silicon dioxide, a common inactive ingredient used to help form the tablet. There are no interactions documented for it.

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

Not sure if Chlorella 500 mg 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.

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

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