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Dietary supplement

Chito-Lean Ingredients & Drug Interactions

by 21st Century

Chito-Lean label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Chito-Lean 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

Chito-Lean is a dietary supplement by 21st Century with 1 active ingredient. Its ingredients are commonly taken for weight management, lowering cholesterol, wound care.Based on those ingredients, 3 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Chitosan, Purified. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Chito-Lean by 21st Century

Ask about any prescription or over-the-counter medication and we check it for interactions with Chito-Lean by 21st Century — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Chito-Lean by 21st Century

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 16, 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.

Chito-Lean contains one active ingredient: purified chitosan, a fiber derived from shellfish shells. Chitosan works by binding to dietary fats and cholesterol in your digestive tract, which may help reduce how much your body absorbs.

The capsule also contains inactive ingredients—gelatin, psyllium, and magnesium stearate—that help form and stabilize the tablet.

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: fat blocker and weight management support.
  • We looked for evidence on: Obesity, Hypercholesterolemia, Body weight, Lipid metabolism.
  • The strongest evidence on file: Chitosan is rated "Possibly Effective" for Obesity (Natural Medicines).
  • Also on file: Chitosan is rated "Insufficient Reliable Evidence To Rate" for Hypercholesterolemia.

The evidence behind chitosan is mixed. It's rated possibly effective for obesity and postoperative recovery (healing after surgery), and possibly effective for high blood pressure.

For Crohn disease and dry eye, there isn't enough reliable evidence in our data to rate how well it works. If you're thinking about using it for one of these reasons, talk with your doctor about whether the strength of the evidence matches what you're hoping to achieve.

The evidence, ingredient by ingredient Chitosan

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.

Chitosan is generally well tolerated in the short term, but quality evidence is limited. The most common side effects are constipation, diarrhea, gas, nausea, and stomach discomfort.

One person with kidney failure reported itching during 12 weeks of use, though it's unclear if chitosan caused it. There isn't enough safety data to use this product during pregnancy or while breastfeeding—avoid it in both cases.

Because chitosan is made from shellfish shells, anyone with a shellfish allergy should steer clear.

Side effects, ingredient by ingredient Chitosan

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 — Chitosan.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 3 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 you take Chito-Lean, double-check with your doctor or pharmacist if you take warfarin (Coumadin) or any other blood thinner—chitosan may increase bleeding risk. Also confirm its use if you take acyclovir (Zovirax) or other antivirals, since chitosan can lower how much antiviral your body absorbs.

No interactions are documented for the other medications we checked.

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.

Chito-Lean may be worth considering if you're interested in weight management or blood pressure support and don't take warfarin or acyclovir. If you take any blood thinners, antivirals, or other regular medications, check with your doctor or pharmacist before starting—especially given the documented interactions with warfarin and acyclovir.

Skip it if you're pregnant, breastfeeding, or allergic to shellfish.

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 Aug 24, 2012.

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 Chito-Lean, straight from the product label.

Brand 21st Century
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Aug 24, 2012
DSLD ID 11143
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
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 Chito-Lean by 21st Century, 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:
1 Capsule(s)
Maximum serving Sizes:
3 Capsule(s)
Servings per container
20
IngredientAmount% DV
Chitosan, Purified1200 mg--

Other ingredients: Gelatin, Psyllium, Magnesium Stearate

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

No Added Sugar, Salt, Yeast, Preservatives or Artificial Flavors. No Ephedra, Ma-Huang or Caffeien.

General Statements

Made in U.S.A.

Unconditionally guaranteed for purity, freshness and label potency.

General

0606

Brand IP Statement(s)

Chito-Lean(TM) Contains Chitosan - The All-Natural Fat Blocker from the Sea

FDA Statement of Identity

Dietary Supplement

Formula

This product contains crustacean ingredients (shrimp shells).

FDA Disclaimer Statement

*This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Precautions

Warning: You should not take Chitosan if you have any kind of Shellfish allergy or are pregnant or breast-feeding. Consult your medical practitioner before using this product or beginning a weight management program. This product is for adult use only and should be taken at least 4 hours before or after ingestion of any fat soluble vitamins, medications or fatty acids.

Keep out of reach of children.

Do not use if product appears to be tampered with or seal is broken.

Suggested/Recommended/Usage/Directions

Suggested Use: As a dietary supplement, take up to 3 capsules with an 8 oz. glass of water 30 minutes before meals, or as directed by a medical practitioner. Not to exceed 12 capsules in a 24 hours period.

Storage

Store at room temperature.

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

See for yourself

Chito-Lean by 21st Century label

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

Chito-Lean 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 Chito-Lean by 21st Century

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Servings per container20 Amounts shown are per serving.

Chitosan, Purified

Interacts with
3 drugs
1200 mg per serving

Chitosan is a fiber-like substance made from the shells of shrimp, crabs, and other shellfish, often marketed for weight loss and cholesterol. The evi...

Chitosan, Purified monograph & interactions

Other (inactive) ingredients: Gelatin, Psyllium, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Chito-Lean by 21st Century Drug Interactions

Want to check YOUR meds against Chito-Lean?

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
3Drugs
3 Moderate

Ingredients driving the most interactions

Chitosan, Purified 3

Individual Drug Interactions

The ingredients in Chito-Lean interact with 3 drugs. Click any drug to see the details.

1 of the 1 ingredient in Chito-Lean interact with drugs. Each result below shows which ingredient is responsible. Chitosan, Purified

Each ingredient & the kinds of drugs it affects

For each ingredient in Chito-Lean 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.

Chitosan, Purified2 drug types · 3 drugs

Acyclovir (Zovirax)

Chitosan can reduce the absorption of acyclovir, potentially increasing the risk for treatment failure.
Clinical research in humans shows that taking chitosan along with acyclovir 200 mg reduces acyclovir absorption. Concomitant administration of chitosan 400 mg or 1000 mg reduced the acyclovir area under the curve (AUC) and peak plasma concentration by about 30% and 40%, respectively, compared with control. Concomitant administration with chitosan 1000 mg also increased time to peak concentration from 1 hour to 2 hours. In vitro research suggests that the mechanism for reduced absorption is due to acyclovir entrapment in chitosan-mucus complexes, which reduces intestinal absorption.

Likelihood Possible Evidence B
Warfarin (Coumadin)

Theoretically, chitosan might increase the risk of bleeding when taken with warfarin.
In a case report, a patient taking warfarin had a significantly increased international normalized ratio (INR) after starting chitosan 1200 mg daily. The INR normalized after chitosan was discontinued and vitamin K was administered. The patient once again started taking chitosan and again had a significant increase in INR. The INR stabilized again once chitosan was discontinued. Researchers theorize that this interaction might occur because chitosan decreases absorption of fat-soluble vitamins, including vitamin K, which could increase the anticoagulant effect of warfarin.

Likelihood Possible Evidence D
Chitosan, Purified full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Chito-Lean, from the product label.

21st Century

See all 21st Century products
Name
21st Century HealthCare, Inc.
Street Address
2119 S. Wilson Street
City
Tempe
State
AZ
ZipCode
85282
Web Address
www.21stcenturyvitamins.com
Pharmacist Counseling Corner

Chito-Lean by 21st Century: Common Questions

Does Chito-Lean by 21st Century interact with any medications?
Yes. Based on its ingredients, Chito-Lean has a known interaction with 3 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Chito-Lean contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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.
What is chitosan, and where does it come from?
Chitosan is a fiber made from shellfish shells, usually from shrimp or crab. It works by binding to fats and cholesterol in your digestive tract so your body doesn't absorb as much of them.
Can I take Chito-Lean if I have a shellfish allergy?
No. Since chitosan is derived from shellfish shells, you should avoid this product if you're allergic to shellfish.
What side effects should I expect?
The most common ones are constipation, diarrhea, gas, stomach discomfort, and nausea. Some people also report a dry throat or fatty stools. Most side effects are mild and short-term.
Is Chito-Lean safe to use during pregnancy or while breastfeeding?
There isn't enough safety data to recommend it in either case. Avoid using it if you're pregnant or breastfeeding, and talk with your doctor or pharmacist if you have questions about alternatives.
Does Chito-Lean really help with weight loss?
The evidence is fair—chitosan is rated possibly effective for obesity. That means some studies show a benefit, but it's not proven to work reliably for everyone. It works best alongside diet and exercise, not as a replacement for them.

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

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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.

Chito-Lean label
Go deeper

The Full Monographs Behind Chito-Lean’s Ingredients

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

Herb & supplement monograph

Chitosan

Interacts with 3 drugs

Chitosan is a fiber-like substance made from the shells of shrimp, crabs, and other shellfish, often marketed for weight loss and cholesterol. The evidence for these benefits is weak, and an...

Read the full Chitosan monograph →
Sources

Sources & How We Checked

Chito-Lean'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 17 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.

Chitosan 17 references
  1. Jing SB, Li L, Ji D, et al. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol 1997;49:721-3. PubMed
  2. Pittler MH, Abbot NC, Harkness EF, Ernst E. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr 1999;53:379-81. PubMed
  3. Ho SC, Tai ES, Eng PH, et al. In the absence of dietary surveillance, chitosan does not reduce plasma lipids or obesity in hypercholesterolaemic obese Asian subjects. Singapore Med J 2001;42:6-10.
  4. Bokura H, Kobayashi S. Chitosan decreases total cholesterol in women: a randomized, double-blind, placebo-controlled trial. Eur J Clin Nutr 2003;57:721-5. PubMed
  5. Mhurchu CN, Poppitt SD, McGill AT, et al. The effect of the dietary supplement, Chitosan, on body weight: a randomised controlled trial in 250 overweight and obese adults. Int J Obes Relat Metab Disord 2004;28:1149-56. PubMed
  6. Huang SS, Sung SH, Chiang CE. Chitosan potentiation of warfarin effect. Ann Pharmacother 2007;41:1912-4. PubMed
  7. Tsai, G. J. and Su, W. H. Antibacterial activity of shrimp chitosan against Escherichia coli. J Food Prot. 1999;62(3):239-243. PubMed
  8. Wuolijoki, E., Hirvela, T., and Ylitalo, P. Decrease in serum LDL cholesterol with microcrystalline chitosan. Methods Find.Exp Clin Pharmacol. 1999;21(5):357-361. PubMed
  9. Nelson, J. L., Alexander, J. W., Gianotti, L., Chalk, C. L., and Pyles, T. Influence of dietary fiber on microbial growth in vitro and bacterial translocation after burn injury in mice. Nutrition 1994;10(1):32-36.
  10. Schiller RN, Barrager E, Schauss EA, and et al. A randomized, double-blind, placebo-controlled study examining the effects of a rapidly soluble chitosan dietary supplement on weight loss and body composition in overweight and mildly obese individuals. J
  11. Koide, S. S. Chitin-chitosan: properties, benefits and risks. Nutrition Research 1998;8(6):1091-1101. DOI
  12. Maezaki Y, Tsuji K, Nakawa, and et al. Hypocholesterolaemic effect of chitosan in adult males. Biosc Biochem Biotech 1993;57:1439-1444.
  13. Kubbinga M, Nguyen MA, Staubach P, et al. The influence of chitosan on the oral bioavailability of acyclovir-a comparative bioavailability study in humans. Pharm Res 2015;32(7):2241-9. PubMed
  14. Jull AB, Ni Mhurchu C, Bennett DA, et al. Chitosan for overweight or obesity. Cochrane Database Syst Rev 2008;(3):CD003892. PubMed
  15. Schmidl D, Werkmeister R, Kaya S, et al. A Controlled, Randomized Double-Blind Study to Evaluate the Safety and Efficacy of Chitosan-N-Acetylcysteine for the Treatment of Dry Eye Syndrome. J Ocul Pharmacol Ther. 2017;33(5):375-382.
  16. Moraru C, Mincea MM, Frandes M, Timar B, Ostafe V. A meta-analysis on randomised controlled clinical trials evaluating the effect of the dietary supplement chitosan on weight loss, lipid parameters and blood pressure. Medicina (Kaunas). 2018;54(6):109. PubMed
  17. García MA, Hensler G, Al-Gousous J, Pielenhofer J, Wagner M, Lennernäs H, Langguth P. Novel food drug interaction mechanism involving acyclovir, chitosan and endogenous mucus. Drug Metab Pharmacokinet. 2023;49:100491. PubMed

See these in context on the Chitosan 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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