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

Diet Duo Ingredients & Drug Interactions

by Swanson

Diet Duo label
See full label image
Capsule Category: Botanical With Nutrients
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 Diet Duo 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

Diet Duo is a dietary supplement by Swanson with 2 active ingredients. 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 LipoSan Ultra Chitosan. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Diet Duo by Swanson

Ask about any prescription or over-the-counter medication and we check it for interactions with Diet Duo by Swanson — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Diet Duo by Swanson

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 23, 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.

Diet Duo contains 2 active ingredients. Phase 2 Carb Controller is included to help manage carbohydrate intake.

LipoSan Ultra Chitosan is a fiber derived from shellfish that works as a lipid binder — it's meant to help reduce how much fat your body absorbs from food. The capsules also contain inactive ingredients: gelatin, gum arabic, rice flour, and magnesium stearate.

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: supports healthy body weight and minimizes carbohydrate and fat impact.
  • We looked for evidence on: Obesity, Hypercholesterolemia, Weight management, Metabolic health.
  • 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.

For chitosan, the evidence shows it's possibly effective for obesity and high blood pressure, and possibly effective for recovery after surgery. For Crohn disease and dry eye, we don't have reliable evidence to say whether it works.

Phase 2 Carb Controller's effectiveness isn't covered in the data we hold.

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 short-term, though quality evidence is limited. The most common side effects are constipation, diarrhea, gas, stomach discomfort, and nausea.

Some people report dryness of the throat or excessive fat in the stool (steatorrhea). One person with kidney failure reported itching during treatment — it's unclear whether chitosan caused it.

Shellfish allergy is a concern since chitosan comes from shellfish. Avoid chitosan during pregnancy and while breastfeeding — there isn't enough safety data to know it's okay in either.

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 taking Diet Duo, check with your doctor or pharmacist if you take warfarin (Coumadin) — chitosan may increase bleeding risk. Also double-check if you take acyclovir (Zovirax) — chitosan may reduce how well it works.

We could not check Phase 2 Carb Controller for drug interactions, so mention that ingredient specifically when you ask.

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.

Diet Duo may be worth considering if you're interested in a carb- and fat-blocking supplement and don't have a shellfish allergy or take warfarin or acyclovir. If you're pregnant, breastfeeding, or take any regular medications, talk with your doctor or pharmacist before starting — especially if you're on a blood thinner or antiviral.

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 Sep 24, 2019.

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 Diet Duo, straight from the product label.

Brand Swanson
Barcode (UPC) 087614040486
Net contents 120 Capsule(s)
Market status On market
Date entered into DSLD Sep 24, 2019
DSLD ID 203357
Product type Botanical With Nutrients
Supplement form Capsule
Dietary claims / uses Nutrient, 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 Diet Duo by Swanson, 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
60
UPC/BARCODE
087614040486
IngredientAmount% DV
Phase 2 Carb Controller1 Gram(s)--
LipoSan Ultra Chitosan500 mg--

Other ingredients: Gelatin, Gum Arabic, Rice Flour, 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.
General Statements

Minimizes the impact of both dietary carbohydrates and fat

Supports a healthy body weight Science-Backed Quality Since 1969

Weight management

Formula

Features chitosan and Phase 2 starch blocker

Features Chitosan and White Kidney Bean

Suggested/Recommended/Usage/Directions

Suggested use: As a dietary supplement, take two capsules with water before each meal. Medications and fat soluble vitamins (A, D, E and K) should be taken at least 4 hours before or after ingestion to ensure absorption.

Precautions

Medications and fat soluble vitamins (A, D, E and K) should be taken at least 4 hours before or after ingestion to ensure absorption.

Warning: For adults only.

Consult your physician before using this or any product if you are pregnant or nursing, taking medication or have a medical condition.

Keep out of reach of children.

Do not use if seal is broken.

Brand IP Statement(s)

Phase 2 Carb Controller is used with permission under license. LipoSan ULTRA is a registered trademark of Primex ehf.

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.

FDA Statement of Identity

Dietary Supplement

General

SWD048 Rev 1 10 09 18

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

See for yourself

Diet Duo by Swanson label

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

Diet Duo 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 Diet Duo by Swanson

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 container60 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.

Phase 2 Carb Controller

1 Gram(s) per serving

LipoSan Ultra Chitosan

Interacts with
3 drugs
500 mg per serving Form: Shellfish

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...

LipoSan Ultra Chitosan monograph & interactions

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

Interaction report

Diet Duo by Swanson Drug Interactions

Want to check YOUR meds against Diet Duo?

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

LipoSan Ultra Chitosan 3

Individual Drug Interactions

The ingredients in Diet Duo interact with 3 drugs. Click any drug to see the details.

1 of the 2 ingredients in Diet Duo interact with drugs. Each result below shows which ingredient is responsible. LipoSan Ultra Chitosan

Each ingredient & the kinds of drugs it affects

For each ingredient in Diet Duo 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.

LipoSan Ultra Chitosan2 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
LipoSan Ultra Chitosan full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Diet Duo, from the product label.

Swanson

See all Swanson products
Name
Swanson Health Products
City
Fargo
State
ND
ZipCode
58104
Phone Number
1-800-437-4148
Web Address
swanson.com
Pharmacist Counseling Corner

Diet Duo by Swanson: Common Questions

Does Diet Duo by Swanson interact with any medications?
Yes. Based on its ingredients, Diet Duo 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?
Diet Duo 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.
Is chitosan safe if I have a shellfish allergy?
No — chitosan is derived from shellfish, so it's a genuine concern if you have that allergy. Don't take this product and talk with your pharmacist about safer alternatives.
What are the most common side effects?
Constipation, diarrhea, gas, and stomach discomfort happen most often. Some people also report nausea or a dry throat. Most side effects are mild and short-term.
Can I take this while pregnant or breastfeeding?
No — there isn't enough safety data for either. Avoid it during pregnancy and while breastfeeding, and talk with your doctor about what's safe for you.
Does it actually help with weight loss?
Chitosan is possibly effective for obesity based on the evidence we have. Phase 2 Carb Controller's effectiveness isn't established in the data we hold, so we can't say how much it helps.
Will it interact with my blood pressure medication?
We don't have interaction data for warfarin or other blood pressure drugs specifically, but if you take any prescription medication — including blood thinners — check it with your pharmacist before starting Diet Duo.

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

Not sure if Diet Duo is safe with your meds?

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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.

Diet Duo label
Go deeper

The Full Monographs Behind Diet Duo’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

Diet Duo'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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