Interactions on record — worth a quick check against your medications. Based on 5 of 6 ingredients. Check your meds →
Dietary supplement

Fiber Formula Ingredients & Drug Interactions

by Trader Joe's

Fiber Formula label
See full label image
Capsule Category: Other Combinations
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 Fiber Formula 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

Fiber Formula is a dietary supplement by Trader Joe's with 6 active ingredients. Its ingredients are commonly taken for constipation, diarrhea, high cholesterol.Based on those ingredients, 2,077 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Marshmallow (Althaea officinalis) root extract, Dietary Fiber, Guar Gum (Cyamopsis tetragonoloba) seed extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Fiber Formula by Trader Joe's

Ask about any prescription or over-the-counter medication and we check it for interactions with Fiber Formula by Trader Joe's — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Fiber Formula by Trader Joe's

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 30, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 1 of its 6 active ingredients.
  • “Proprietary Fiber Blend (Combination)” is a proprietary blend — the label gives one combined amount (3.40 Gram(s)) without saying how much of each component you get.

Trader Joe's Fiber Formula contains five active ingredients: marshmallow root extract, psyllium, pectin, guar gum, and oat. These are all soluble and insoluble fiber sources designed to support digestive health.

The capsules also contain inactive ingredients—cellulose, vegetable capsule material, vegetable glycerin, magnesium stearate, and silicon dioxide—which are common fillers and binders. Marshmallow root adds mucilage; pectin is a soluble fiber from fruit; guar gum is a seed extract thickener; and oat provides beta-glucan fiber.

Psyllium is included but we don't hold detailed safety and interaction data for it, so if you have specific questions about that ingredient, talk it over with your pharmacist.

Does it work?

Strong 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
Strong

Clinical evidence supports at least one of this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: Digestive health and bowel regularity.
  • We looked for evidence on: Constipation, Diarrhea, Irritable bowel syndrome (IBS), Dyslipidemia, Hypercholesterolemia, Colonic motility — and 2 related terms.
  • The strongest evidence on file: Black Psyllium is rated "Effective" for Constipation (Natural Medicines).
  • Also on file: Oats is rated "Likely Effective" for Dyslipidemia.
  • Also on file: Pectin is rated "Possibly Effective" for Hypercholesterolemia.

The evidence for this product's ingredients is mixed. Oat has strong evidence (Likely Effective) for lowering cholesterol and supporting heart health.

Pectin and guar gum are rated Possibly Effective for cholesterol and blood sugar control. Marshmallow, however, lacks reliable evidence for the conditions it's traditionally used for—diarrhea, vaginal infections, eczema, and respiratory infections all fall into Insufficient Reliable Evidence.

Psyllium's effectiveness rating isn't on file with us. For fiber's general digestive role, the ingredients here are standard, but the specific health claims depend on which part of the formula matters most to your situation.

The evidence, ingredient by ingredient Black Psyllium Marshmallow Pectin Guar Gum Oats

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 4 of the 5 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 5 of 5.
  • General safety write-ups exist for 5 of 5.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Trader Joe's Fiber Formula is generally well tolerated when taken with plenty of water. The most common side effects are mild: gas, bloating, loose stools, diarrhea, abdominal cramps, and an unpleasant taste—especially when you first start.

These usually fade as your body adjusts. Start low and increase slowly to minimize discomfort.

A rare but serious risk is bowel obstruction if you don't drink enough fluid, so hydration is essential. Marsh­mallow has limited human safety data and should be avoided in pregnancy and while breastfeeding.

For pectin during pregnancy and breastfeeding, concentrated supplement amounts haven't been well studied—dietary amounts from food are fine, so talk with your doctor about the supplement dose. Guar gum's supplement form in pregnancy and breastfeeding is also under-studied; again, food amounts are likely okay.

Oat as a food is considered safe in pregnancy and breastfeeding. Allergic reactions to pectin are rare but possible, including anaphylaxis in sensitive individuals.

Side effects, ingredient by ingredient Black Psyllium Marshmallow Pectin Guar Gum Oats

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?
  • 5 of the 5 matched ingredients can interact with medications — Black Psyllium, Pectin, Marshmallow, Oats, Guar Gum.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; diabetes medications; heart-rhythm medications; lithium.
  • For scale: 2,078 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.

If you take lithium, blood pressure or cholesterol medication (especially lovastatin), heart rhythm medication (digoxin), diabetes medication (metformin or insulin), tetracycline or penicillin antibiotics, or birth control pills, check with your doctor or pharmacist first. Guar gum and marshmallow may slow absorption of many oral medications, so space them 30–60 minutes apart from your other pills.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with clinical evidence supporting its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

This is a fiber supplement designed for digestive support. It's a reasonable choice if you're looking for a plant-based fiber blend, but you must take it with plenty of water and watch for interactions with blood sugar, heart, and antibiotic medications—especially if you take lithium.

Start with a small dose to let your gut adjust. Before you begin, check all your medications with your doctor or pharmacist, particularly if you take diabetes drugs, insulin, antibiotics, or heart medications.

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

Assessment coverage: 5 of 6 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Aug 22, 2017.

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 Fiber Formula, straight from the product label.

Brand Trader Joe's
Net contents 112 Capsule(s)
Market status On market
Date entered into DSLD Aug 22, 2017
DSLD ID 75791
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Vegetarian, Adult (18 - 50 Years), 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 Fiber Formula by Trader Joe's, 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:
8 Capsule(s)
Maximum serving Sizes:
8 Capsule(s)
Servings per container
14
IngredientAmount% DV
Calories15 Calorie(s)--
Total Carbohydrates4 Gram(s)1%
Dietary Fiber4 Gram(s)16%
Marshmallow (Althaea officinalis) root extract0 NP--
Proprietary Fiber Blend (Combination)3.4 Gram(s)--
Psyllium0 NP--
Pectin0 NP--
Guar Gum (Cyamopsis tetragonoloba) seed extract0 NP--
Oat0 NP--

Other ingredients: Cellulose, Vegetable Capsule, Vegetable Glycerin, Magnesium Stearate, 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.
FDA Statement of Identity

Dietary Supplement

Seals/Symbols

Vegetarian

g Gluten Free

Precautions

Do not exceed recommended dosage.

Caution: Do not use if pregnant or nursing. If taking prescription drugs, consult your healthcare practitioner prior to use.

Suggested/Recommended/Usage/Directions

Recommendations: Day 1 through 14: Four capsules in the morning and four capsules at night with 8 ounces of water. May be taken as eight capsules at night with 8 ounces of water.

General Statements

Actual size of capsule

Formulation

Vegetarian

No gluten ingredients used

General

LS98457TJ.A02

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

See for yourself

Fiber Formula by Trader Joe's label

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

Fiber Formula 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 Fiber Formula by Trader Joe's

These are the 6 active ingredients this product is made of. Select any to open its full monograph.

Serving size8 Capsule(s) Dosage formCapsule Servings per container14 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
4 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

Proprietary Fiber Blend (Combination)

3.4 Gram(s) per serving

Other (inactive) ingredients: Cellulose, Vegetable Capsule, Vegetable Glycerin, Magnesium Stearate, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Fiber Formula by Trader Joe's Drug Interactions

Want to check YOUR meds against Fiber Formula?

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
2,077Drugs
2,059 Moderate 18 Minor

Ingredients driving the most interactions

Marshmallow (Althaea officinalis) root extract 2,040
Dietary Fiber 2,025
Guar Gum (Cyamopsis tetragonoloba) seed extract 2,025
Oat 86
Pectin 23

Individual Drug Interactions

The ingredients in Fiber Formula interact with 2,077 drugs. Click any drug to see the details.

5 of the 6 ingredients in Fiber Formula interact with drugs. Each result below shows which ingredient is responsible. Marshmallow (Althaea officinalis) root extract Dietary Fiber Guar Gum (Cyamopsis tetragonoloba) seed extract Oat Pectin

Each ingredient & the kinds of drugs it affects

For each ingredient in Fiber Formula with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Marshmallow (Althaea officinalis) root extract3 drug types · 2,040 drugs

Lithium

Theoretically, due to potential diuretic effects, marshmallow might reduce excretion and increase levels of lithium.
Marshmallow is thought to have diuretic properties. To avoid lithium toxicity, the dose of lithium might need to be decreased when used with marshmallow.

Likelihood Probable Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, marshmallow flower might have antiplatelet effects.
Animal research suggests that marshmallow flower extract has antiplatelet effects. However, the root and leaf of marshmallow, not the flower, are the plant parts most commonly found in dietary supplements. Theoretically, use of marshmallow flower with anticoagulant/antiplatelet drugs can have additive effects, and might increase the risk for bleeding in some patients.

Likelihood Unlikely Evidence D
Oral Drugs

Theoretically, mucilage in marshmallow might impair absorption of oral drugs.
Marshmallow contains mucilage which can affect oral drug absorption. To avoid changes in absorption, take marshmallow 30-60 minutes after oral medications.

Likelihood Possible Evidence D
Marshmallow (Althaea officinalis) root extract full monograph & interactions

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

Guar Gum (Cyamopsis tetragonoloba) seed extract5 drug types · 2,025 drugs

Ethinyl Estradiol

Theoretically, guar gum might reduce the absorption of ethinyl estradiol, potentially decreasing its effectiveness.
Animal research shows that taking guar gum with ethinyl estradiol decreases ethinyl estradiol absorption. However, this effect has not been reported in humans.

Likelihood Possible Evidence D
Metformin (Glucophage)

Guar gum might reduce the absorption of metformin, potentially decreasing its effectiveness.
A small study in healthy volunteers shows that guar gum reduces the absorption rate of metformin.

Likelihood Probable Evidence B
Oral Drugs

Guar gum might reduce the absorption of some oral drugs, potentially decreasing their effectiveness.
Clinical research shows that guar gum reduces or slows absorption of medications such as penicillin and metformin. To avoid changes in absorption, take guar gum 30-60 minutes after oral medications.

Likelihood Possible Evidence B
Penicillin

Guar gum might reduce the absorption of penicillin, potentially decreasing its effectiveness.
A small clinical study in healthy volunteers shows that taking guar gum with penicillin results in decreased penicillin absorption and reduced penicillin levels.

Likelihood Probable Evidence B
Digoxin (Lanoxin)

Guar gum might slow digoxin absorption, but it does not seem to impact how much digoxin is absorbed overall.
Two small studies in healthy volunteers show no change in the overall extent of digoxin absorption, although early absorption was slowed, when taken with guar gum.

Likelihood Possible Evidence B
Guar Gum (Cyamopsis tetragonoloba) seed extract full monograph & interactions

Oat2 drug types · 86 drugs

Antidiabetes Drugs

Theoretically, oats may have additive effects with antidiabetic agents and might increase the risk of hypoglycemia.
Consuming oats can decrease blood glucose in patients with diabetes. In those who require insulin, taking oats 100 grams daily for 2 days reduces the insulin dose required to achieve metabolic control.

Likelihood Possible Evidence D
Insulin

Concomitant use of oats and insulin might increase the risk of hypoglycemia.
In patients with insulin-dependent type 2 diabetes, taking oats 100 grams daily for 2 days reduces the insulin dose required to achieve metabolic control.

Likelihood Possible Evidence B
Oat full monograph & interactions

Pectin3 drug types · 23 drugs

Digoxin (Lanoxin)

Theoretically, pectin might reduce the absorption of digoxin, potentially decreasing its effectiveness.
A small clinical study shows that taking digoxin with a kaolin-pectin suspension reduces the absorption of digoxin by about 62%. It is unclear if these effects are due to pectin, kaolin, or the combination.

Likelihood Possible Evidence B
Lovastatin (Mevacor)

Theoretically, pectin might reduce the absorption of lovastatin, potentially decreasing its effectiveness.
Case reports suggest that concomitant use of pectin and lovastatin might reduce the cholesterol-lowering effect of lovastatin, possibly due to reduced intestinal absorption of lovastatin.

Likelihood Possible Evidence D
Tetracycline Antibiotics

Theoretically, pectin might reduce the absorption of tetracycline antibiotics, potentially decreasing their effectiveness.
A small clinical study shows that taking tetracycline with bismuth subsalicylate in a kaolin-pectin suspension reduces the absorption of tetracycline by about 34%. It is unclear if these effects are due to pectin, kaolin, bismuth subsalicylate, or the combination.

Likelihood Possible Evidence B
Pectin full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Fiber Formula, from the product label.

Trader Joe's

See all Trader Joe's products
Name
Trader Joe's
Street Address
800 S. Shamrock
City
Monrovia
State
CA
ZipCode
91016
Pharmacist Counseling Corner

Fiber Formula by Trader Joe's: Common Questions

Does Fiber Formula by Trader Joe's interact with any medications?
Yes. Based on its ingredients, Fiber Formula has a known interaction with 2,077 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Fiber Formula contains 6 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 this if I'm on birth control?
The guar gum in this formula may reduce absorption of ethinyl estradiol (a common birth control ingredient), potentially lowering its effectiveness. Talk with your doctor or pharmacist to see if you need to adjust the timing or dose of your birth control, or if this product is right for you.
What are the most common side effects?
Gas, bloating, loose stools, diarrhea, belly cramps, and an unpleasant taste are the typical ones. They're usually mild and improve as your body gets used to the extra fiber. Starting with a small dose and drinking lots of water will help.
Is it safe to take during pregnancy?
Marshmallow should be avoided in pregnancy because there isn't enough safety data. Oat as a food is considered safe. Pectin and guar gum in concentrated supplement form haven't been well studied during pregnancy, so talk with your doctor about whether this product is okay for you right now.
Why do I need to drink so much water with this?
These fibers absorb water and swell in your digestive tract. Without enough fluid, they can cause severe blockage in your esophagus or small intestine. It's a real risk, so drink generously.
Does this product actually help with cholesterol or blood sugar?
Oat and pectin have decent evidence for lowering cholesterol. Guar gum may help with both cholesterol and blood sugar. Marshmallow doesn't have reliable evidence for the conditions it's commonly used for—that's a gap in the data.
Can I take this with my other medications?
Maybe—it depends on what you take. This formula can interact with a wide range of drugs, from antibiotics to heart and diabetes medications. Use the medication checker on this page with your exact prescriptions, and talk with your pharmacist before you start.

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.

Fiber Formula label
Go deeper

The Full Monographs Behind Fiber Formula’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 → Herb & supplement monograph

Marshmallow

Interacts with 2,040 drugs

Marshmallow root is a traditional herb rich in soothing, gel-like fibers called mucilage, which is why it has long been used for coughs, sore throats, and stomach irritation. Evidence for th...

Read the full Marshmallow monograph → Herb & supplement monograph

Pectin

Interacts with 23 drugs

Pectin is a natural soluble fiber found in fruits like apples and citrus, and it is widely used in foods and as a fiber supplement. It may modestly help with cholesterol, blood sugar, and di...

Read the full Pectin monograph → Herb & supplement monograph

Guar Gum

Interacts with 2,025 drugs

Guar gum is a soluble, gel-forming fiber from the guar bean that may modestly help with cholesterol, blood sugar, and bowel regularity. It is generally safe in food amounts, but concentrated...

Read the full Guar Gum monograph → Herb & supplement monograph

Oats

Interacts with 86 drugs

Oats are a well-studied whole grain whose soluble fiber (beta-glucan) can help lower cholesterol and support heart health when eaten regularly. As a food, oats are safe for most people, and...

Read the full Oats monograph →
Sources

Sources & How We Checked

Fiber Formula'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 73 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 →

Marshmallow 5 references
  1. Monographs on the medicinal uses of plant drugs. Exeter, UK: European Scientific Co-op Phytother, 1997.
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  5. Hage-Sleiman R, Mroueh M, Daher CF. Pharmacological evaluation of aqueous extract of Althaea officinalis flower grown in Lebanon. Pharm Biol 2011;49(3):327-33.

See these in context on the Marshmallow monograph →

Pectin 11 references
  1. Jaakkola MS, et al. Asthma caused by occupational exposure to pectin. J Allergy Clin Immunol 1997;100:575-6. PubMed
  2. Westphal W, et al. [Exogenous allergic asthma following pectin exposure-a new occupational allergen]. Pneumologie 1990;44(Suppl 1):337-8.
  3. Baldwin JL, et al. Pectin-induced occupational asthma. Chest 1993;104:1936-7. PubMed
  4. Cohen AJ, Forse MS, Tarlo SM. Occupational asthma caused by pectin inhalation during the manufacture of jam. Chest 1993;103:309-11.
  5. Kraut A, et al. Christmas candy maker's asthma. IgG4-mediated pectin allergy. Chest 1992;102:1605-7. PubMed
  6. Richter WO, Jacob BG, Schwandt P. Interaction between fibre and lovastatin. Lancet 1991;338:706.
  7. Albert KS, Ayres JW, DiSanto AR, et al. Influence of kaolin-pectin suspension on digoxin bioavailability. J Pharm Sci 1978;67:1582-6. PubMed
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  10. Federal Register April 17,2003. Anti-Diarrheal Products for over-the-counter human use; final monograph. Available at: http://www.fda.gov/OHRMS/DOCKETS/98fr/03-9380.pdf (Accessed 27 December 2004).
  11. Washio K, Nakamura M, Sato N, et al. Anaphylaxis in a pectin- and cashew nut-allergic child caused by a citrus bath. Allergol Int 2022;71(1):155-157. PubMed

See these in context on the Pectin monograph →

Guar Gum 26 references
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  2. Huupponen R, Seppala P, Iisalo E. Effect of guar gum, a fibre preparation, on digoxin and penicillin absorption in man. Eur J Clin Pharmacol 1984;26:279-81. PubMed
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  6. Vuorinen-Markkola H, Sinisalo M, Koivisto VA. Guar gum in insulin-dependent diabetes: effects on glycemic control and serum lipoproteins. Am J Clin Nutr 1992;56:1056-1060. PubMed
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  10. Chuang LM, Jou TS, Yang WS, et al. Therapeutic effect of guar gum in patients with non-insulin-dependent diabetes mellitus. J Formos Med Assoc 1992;91:15-9.
  11. Ebeling P, Yki-Jarvinen H, Aro A, et al. Glucose and lipid metabolism and insulin sensitivity in type 1 diabetes: the effect of guar gum. Am J Clin Nutr 1988;48:98-103. PubMed
  12. Scheen AJ. Clinical pharmacokinetics of metformin. Clin Pharmacokinet 1996;30:359-71. PubMed
  13. Knopp RH, Superko HR, Davidson M, et al. Long-term blood cholesterol-lowering effects of a dietary fiber supplement. Am J Prev Med 1999;17:18-23. PubMed
  14. Patrick PG, Gohman SM, Marx SC, et al. Effect of supplements of partially hydrolyzed guar gum on the occurrence of constipation and use of laxative agents. J Am Diet Assoc 1998;98:912-4. PubMed
  15. Osterlund P, Ruotsalainen T, Korpela R, et al. Lactobacillus supplementation for diarrhoea related to chemotherapy of colorectal cancer: a randomised study. Br J Cancer 2007;97:1028-34. PubMed
  16. Lembcke B, Hasler K, Kramer P, et al. Plasma digoxin concentrations during administration of dietary fibre (guar gum) in man. Z Gastroenterol 1982;20;164-7.
  17. Riikonen, S., Savonius, H., Gylling, H., Nikkila, K., Tuomi, A. M., and Miettinen, T. A. Oral guar gum, a gel-forming dietary fiber relieves pruritus in intrahepatic cholestasis of pregnancy. Acta Obstet.Gynecol.Scand. 2000;79(4):260-264. DOI
  18. Kovacs, E. M., Westerterp-Plantenga, M. S., Saris, W. H., Goossens, I., Geurten, P., and Brouns, F. The effect of addition of modified guar gum to a low-energy semisolid meal on appetite and body weight loss. Int.J.Obes.Relat Metab Disord. 2001;25(3):307 PubMed
  19. Halama, W. H. and Mauldin, J. L. Distal esophageal obstruction due to a guar gum preparation (Cal-Ban 3000). South.Med.J. 1992;85(6):642-645. PubMed
  20. Landin, K., Holm, G., Tengborn, L., and Smith, U. Guar gum improves insulin sensitivity, blood lipids, blood pressure, and fibrinolysis in healthy men. Am.J.Clin.Nutr. 1992;56(6):1061-1065. PubMed
  21. Cicero, A. F., Derosa, G., Manca, M., Bove, M., Borghi, C., and Gaddi, A. V. Different effect of psyllium and guar dietary supplementation on blood pressure control in hypertensive overweight patients: a six-month, randomized clinical trial. Clin.Exp.Hyp PubMed
  22. Simons LA, Gayst S, Balasubramaniam S, Ruys J. Long-term treatment of hypercholesterolaemia with a new palatable formulation of guar gum. Atherosclerosis 1982;45:101-108. PubMed
  23. Salenius JP, Harju E, Jokela H, et al. Long term effects of guar gum on lipid metabolism after carotid endarterectomy. BMJ 1-14-1995;310:95-96. PubMed
  24. Gylling, H., Riikonen, S., Nikkila, K., Savonius, H., and Miettinen, T. A. Oral guar gum treatment of intrahepatic cholestasis and pruritus in pregnant women: effects on serum cholestanol and other non-cholesterol sterols. Eur.J.Clin.Invest 1998;28(5):35 PubMed
  25. Brillantino A, Iacobellis F, Izzo G, et al. Maintenance therapy with partially hydrolyzed guar gum in the conservative treatment of chronic anal fissure: results of a prospective, randomized study. Biomed Res Int 2014;2014:964942. PubMed
  26. Polymeros D, Beintaris I, Gaglia A, et al. Partially hydrolyzed guar gum accelerates colonic transit time and improves symptoms in adults with chronic constipation. Dig Dis Sci 2014;59(9):2207-14. PubMed

See these in context on the Guar Gum monograph →

Oats 13 references
  1. Cooper SG, Tracey EJ. Small-bowel obstruction caused by oat-bran bezoar. N Engl J Med 1989;320:1148-9. DOI
  2. Pick ME, Hawrysh ZJ, Gee MI, et al. Oat bran concentrate bread products improve long-term control of diabetes: a pilot study. J Am Diet Assoc 1996;96:1254-61. PubMed
  3. Braaten JT, Scott FW, Wood PJ, et al. High beta-glucan oat bran and oat gum reduce postprandial blood glucose and insulin in subjects with and without type 2 diabetes. Diabet Med 1994;11:312-8.
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  6. Foulke J. FDA Allows Whole Oat Foods To Make Health Claim on Reducing the Risk of Heart Disease. FDA Talk Paper. 1997. Available at: http://www.fda.gov/bbs/topics/ANSWERS/ANS00782.html.
  7. Chandalia M, Garg A, Lutjohann D, et al. Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus. N Engl J Med 2000;342:1392-8. PubMed
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  10. Delgado G, Kleber ME, Krämer BK, et al. Dietary intervention with oatmeal in patients with uncontrolled type 2 diabetes mellitus - A crossover study. Exp Clin Endocrinol Diabetes. 2019;127(9):623-629. PubMed
  11. Sobhan M, Hojati M, Vafaie SY, Ahmadimoghaddam D, Mohammadi Y, Mehrpooya M. The efficacy of colloidal oatmeal cream 1% as add-on therapy in the management of chronic irritant hand eczema: A double-blind study. Clin Cosmet Investig Dermatol. 2020;13:241-25
  12. Hou Q, Li Y, Li L, Cheng G, Sun X, Li S, Tian H. The metabolic effects of oats intake in patients with type 2 diabetes: A systematic review and meta-analysis. Nutrients. 2015;7(12):10369-87. PubMed
  13. González-Afonso M, Cañas JA, Sastre B, et al. A Case of Anaphylaxis After Ingestion of Oats: Research Into New Allergens. J Investig Allergol Clin Immunol 2022;32(6):506-508. PubMed

See these in context on the Oats monograph →

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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.

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