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

Prebiotic Fiber with Fibersol-2 Ingredients & Drug Interactions

by NOW

Prebiotic Fiber with Fibersol-2 label
See full label image
Powder Category: Fiber And Other 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 Prebiotic Fiber with Fibersol-2 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

Prebiotic Fiber with Fibersol-2 is a dietary supplement by NOW with 2 active ingredients. Its ingredients are commonly taken for constipation, diarrhea, high cholesterol.Based on those ingredients, 2,025 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Dietary Fiber. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Prebiotic Fiber with Fibersol-2 by NOW

Ask about any prescription or over-the-counter medication and we check it for interactions with Prebiotic Fiber with Fibersol-2 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.
Computed from our clinical databases

HelloPharmacist Scorecard of Prebiotic Fiber with Fibersol-2 by NOW

Four independent checks of what is known — a summary of the available information, not a grade of the product itself.

Evidence for Intended Use
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
Not assessable

The stated purpose hasn't been mapped to our evidence data yet.

Why this rating?
  • We haven't mapped this product's purpose to our evidence data yet — it'll be graded on the next content refresh.
Ingredient Transparency
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.
Known Interaction Concern
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 — Black Psyllium.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: heart-rhythm medications; lithium.
  • For scale: 2,026 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.
Safety Information
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.

HelloPharmacist summaryFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

Assessment coverage: 1 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Oct 24, 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 Prebiotic Fiber with Fibersol-2, straight from the product label.

Brand NOW
Barcode (UPC) 733739059079
Net contents 12 Ounce(s); 340 Gram(s)
Market status On market
Date entered into DSLD Oct 24, 2024
DSLD ID 313983
Product type Fiber And Other Nutrients
Supplement form Powder
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Kosher, Gluten Free, Dairy 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 Prebiotic Fiber with Fibersol-2 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:
12 Gram(s)
Maximum serving Sizes:
12 Gram(s)
Servings per container
28
UPC/BARCODE
733739059079
IngredientAmount% DV
Calories20 Calorie(s)--
Total Carbohydrates12 Gram(s)4%
Dietary Fiber11 Gram(s)39%
Soluble Fiber11 Gram(s)--
Fibersol-2 Digestion-Resistant Maltodextrin12 Gram(s)--

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 usage: Mix 2 level tablespoons daily in 8 oz. of water or other beverage to supplement your meal.

Formula

Fibersol-2 is a tasteless, soluble fiber derived from non-GMO corn that can help manage hunger and promote a feeling of fullness up to two hours after a typical meal in healthy adults while also helping maintain healthy, normal glucose levels. Fibersol-2 also acts as a prebiotic fiber that can help to nourish intestinal flora and maintain a healthy intestinal tract environment.

Excellent source of Fiber

Triangle K (Kosher)

Formulation

NOW Prebiotic Fiber with Fibersol-2 dissolves rapidly in water or your favorite beverage and is a convenient and effective way to help maintain regularity.

Natural color variation may occur in this product.

Hunger management Pure powder Maintains regularity

Non-GMO

Vegetarian/Vegan

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

Packaged and quality tested in the USA.

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.

Precautions

Caution: For adults only.

Consult your physician if pregnant/nursing, taking medication, or have a medical condition.

Keep out of reach of children.

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

Storage

Store in a cool, dry place after opening.

This product is sold by weight not volume.

FDA Statement of Identity

A Dietary Supplement

Seals/Symbols

Triangle K (Kosher)

GMP Quality Assured

General Statements

Digestive Family owned since 1968.

Brand IP Statement(s)

Fibersol-2 is a registered trademark of ADM/Matsutani LLC.

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

See for yourself

Prebiotic Fiber with Fibersol-2 by NOW label

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

Prebiotic Fiber with Fibersol-2 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 Prebiotic Fiber with Fibersol-2 by NOW

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

Serving size12 Gram(s) Dosage formPowder Servings per container28 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.

Dietary Fiber

Interacts with
2,025 drugs
11 Gram(s) per serving

Black psyllium is a soluble-fiber supplement made from the seeds of a Plantago plant, used mostly to ease constipation and support digestive health. I...

Dietary Fiber monograph & interactions
  • › Soluble Fiber

Fibersol-2 Digestion-Resistant Maltodextrin

12 Gram(s) per serving
Interaction report

Prebiotic Fiber with Fibersol-2 by NOW Drug Interactions

Prebiotic Fiber with Fibersol-2 contains 2 ingredients, and 1 of them has known drug interactions. Altogether it interacts with 2,025 medications. Here’s the picture, then you can look up your own drug.

Want to check YOUR meds against Prebiotic Fiber with Fibersol-2?

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
2,025Drugs
23 Moderate 2,002 Minor

Ingredients driving the most interactions

Dietary Fiber 2,025

Individual Drug Interactions

The ingredients in Prebiotic Fiber with Fibersol-2 interact with 2,025 drugs. Click any drug to see the details.

1 of the 2 ingredients in Prebiotic Fiber with Fibersol-2 interact with drugs. Each result below shows which ingredient is responsible. Dietary Fiber

Each ingredient & the kinds of drugs it affects

For each ingredient in Prebiotic Fiber with Fibersol-2 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.

Dietary Fiber7 drug types · 2,025 drugs

Carbamazepine (Tegretol)

Theoretically, black psyllium might reduce the effects of carbamazepine and increase the risk for convulsions.
Theoretically, black psyllium might reduce carbamazepine absorption. A preliminary study using blond psyllium reported decreased carbamazepine bioavailability due to binding of the drug to psyllium, as well as reduction of available fluid in the gut for dissolution of the drug. This interaction may also occur with black psyllium.

Likelihood Probable Evidence D
Lithium

Theoretically, taking black psyllium at the same time as lithium might reduce lithium absorption.
The fiber in black psyllium might reduce lithium absorption and plasma levels. Some case reports describe a reduction in plasma lithium levels with concomitant administration of blond psyllium. This was reversed when psyllium was stopped. This interaction may also occur with black psyllium.

Likelihood Probable Evidence D
Metformin (Glucophage)

Theoretically, black psyllium might increase the therapeutic and adverse effects of metformin.
Animal research shows that concurrent consumption of blond psyllium with metformin slows and increases the absorption of metformin. This interaction may also occur with black psyllium. To avoid changes in absorption, take psyllium 30-60 minutes after metformin.

Likelihood Possible Evidence D
Olanzapine (Zyprexa)

Theoretically, taking black psyllium at the same time as olanzapine might reduce olanzapine absorption.
The fiber in black psyllium might decrease the absorption of olanzapine. A single case report describes a reduction in the effectiveness of olanzapine when it was concomitantly administered with an unspecified type of psyllium 3 grams orally twice daily. This effect was reversed when psyllium was stopped.

Likelihood Possible Evidence D
Digoxin (Lanoxin)

Theoretically, taking black psyllium at the same time as digoxin might reduce digoxin absorption and decrease digoxin levels.
Psyllium might bind digoxin in the gut. However, some clinical evidence suggests that psyllium does not impact digoxin absorption.

Likelihood Unlikely Evidence B
Ethinyl Estradiol

Theoretically, taking black psyllium at the same time as ethinyl estradiol might alter levels of estradiol.
Concurrent use of blond psyllium with ethinyl estradiol results in a slight increase in the extent of ethinyl estradiol absorption and a slower rate of absorption. This is unlikely to be clinically significant.

Likelihood Unlikely Evidence D
Oral Drugs

Theoretically, psyllium might increase, decrease, or have no effect on the absorption of oral drugs.
Psyllium seems to have variable effects on drug absorption. To avoid changes in absorption, take psyllium 30-60 minutes after oral medications. Animal research shows that blond psyllium delays and increases the absorption of metformin and ethinyl estradiol. Case reports and animal research suggest that blond psyllium might reduce absorption of lithium, digoxin, olanzapine, and carbamazepine. Finally, some pharmacokinetic studies show that psyllium does not affect the absorption of levothyroxine or warfarin. Although many of these studies evaluated blond psyllium, the fiber content in black psyllium may have similar effects.

Likelihood Possible Evidence B
Dietary Fiber full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Prebiotic Fiber with Fibersol-2, 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
nowfoods.com
Pharmacist Counseling Corner

Prebiotic Fiber with Fibersol-2 by NOW: Common Questions

Does Prebiotic Fiber with Fibersol-2 by NOW interact with any medications?
Yes. Based on its ingredients, Prebiotic Fiber with Fibersol-2 has a known interaction with 2,025 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Prebiotic Fiber with Fibersol-2 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.

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

Not sure if Prebiotic Fiber with Fibersol-2 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.

Prebiotic Fiber with Fibersol-2 label
Go deeper

The Full Monographs Behind Prebiotic Fiber with Fibersol-2’s Ingredients

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

Herb & supplement monograph

Black Psyllium

Interacts with 2,025 drugs

Black psyllium is a soluble-fiber supplement made from the seeds of a Plantago plant, used mostly to ease constipation and support digestive health. It is best known and most studied for rel...

Read the full Black Psyllium monograph →
Sources

Sources & How We Checked

Prebiotic Fiber with Fibersol-2'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 18 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.

Black Psyllium 18 references
  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  3. Covington TR, et al. Handbook of Nonprescription Drugs. 11th ed. Washington, DC: American Pharmaceutical Association, 1996.
  4. Etman M. Effect of a bulk forming laxative on the bioavailablility of carbamazepine in man. Drug Dev Ind Pharm 1995;21:1901-6.
  5. Perlman BB. Interaction between lithium salts and ispaghula husk. Lancet 1990;335:416.
  6. Vaswani SK, Hamilton RG, Valentine MD, Adkinson NF. Psyllium laxative-induced anaphylaxis, asthma, and rhinitis. Allergy 1996;51:266-8. PubMed
  7. Lantner RR, Espiritu BR, Zumerchik P, Tobin MC. Anaphylaxis following ingestion of a psyllium-containing cereal. JAMA 1990;264:2534-6. DOI
  8. Kaplan MJ. Anaphylactic reaction to "Heartwise." N Engl J Med 1990;323:1072-3. DOI
  9. Nordstrom M, Melander A, Robertsson E, Steen B. Influence of wheat bran and of a bulk-forming ispaghula cathartic on the bioavailability of digoxin in geriatric in-patients. Drug Nutr Interact 1987;5:67-9..
  10. Robinson DS, Benjamin DM, McCormack JJ. Interaction of warfarin and nonsystemic gastrointestinal drugs. Clin Pharmacol Ther 1971;12:491-5. PubMed
  11. Garcia JJ, Fernandez N, Diez MJ, et al. Influence of two dietary fibers in the oral bioavailability and other pharmacokinetic parameters of ethinyloestradiol. Contraception 2000;62:253-7. PubMed
  12. Fernandez N, Lopez C, Díez R, et al. Drug interactions with the dietary fiber Plantago ovata husk. Expert Opin Drug Metab Toxicol 2012;8(11):1377-86.
  13. Semen plantaginis in: WHO Monographs on Selected Medicinal Plants, volume 1. World Health Organization, Geneva, 1999. Available at http://apps.who.int/medicinedocs/en/d/Js2200e/. Accessed November 26, 1026.
  14. Code of Federal Regulations, Title 21 (21CFR 101.17). Food labeling warning, notice, and safe handling statements. Available at www.ecfr.gov/cgi-bin/text-idx?SID=20f647d3b74161501f46564b915b4048&mc=true&node=se21.2.101_117&rgn=div8. Accessed December 3, 2
  15. Code of Federal Regulations, Title 21 (21CFR 201.319). Specific labeling requirements - water-soluble gums, hydrophilic gums, and hydrophilic mucilloids. Available at www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=201.319. Accessed Dece
  16. Diez R, Garcia JJ, Diez MJ, Sierra M, Sahagun AM, Fernandez N. Influence of Plantago ovata husk (dietary fiber) on the bioavailability and other pharmacokinetic parameters of metformin in diabetic rabbits. BMC Complement Altern Med. 2017 Jun 7;17(1):298. PubMed
  17. Chiu AC, Sherman SI. Effects of pharmacological fiber supplements on levothyroxine absorption. Thyroid. 1998;8(8):667-71. PubMed
  18. Merrick C, Madden CA, Capurso NA. A Case of Blunted Orally Disintegrating Olanzapine Effect Due to Coadministered Psyllium. J Clin Psychiatry 2021;82(2):20cr13633. PubMed

See these in context on the Black Psyllium 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