Interactions on record — worth a quick check against your medications. Based on 4 of 6 ingredients. Check your meds →
Dietary supplement

Fiber Formula Ingredients & Drug Interactions

by CVS Health

Fiber Formula label
See full label image
Capsule Category: Botanical With Nutrients
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 CVS Health with 6 active ingredients. Its ingredients are commonly taken for constipation, diarrhea, high cholesterol.Based on those ingredients, 2,049 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Marshmallow Root Extract, Dietary Fiber, Guar Gum 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 CVS Health

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

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HelloPharmacist Scorecard of Fiber Formula by CVS Health

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” is a proprietary blend — the label gives one combined amount (3.40 Gram(s)) without saying how much of each component you get.

This formula contains five active ingredients. Marshmallow root extract is included for soothing properties; pectin and guar gum seed extract are both soluble fibers meant to support digestive health and cholesterol levels; oat bran adds insoluble fiber; and psyllium rounds out the fiber blend.

The product also contains inactive ingredients—cellulose, vegetable capsule material, magnesium stearate, and silicon dioxide—which are fillers and binders that help form and stabilize the capsule.

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: colon function and toxin elimination.
  • We looked for evidence on: Constipation, Diarrhea, Irritable bowel syndrome (IBS), bowel regularity, digestive cleansing, waste elimination.
  • The strongest evidence on file: Black Psyllium is rated "Effective" for Constipation (Natural Medicines).
  • Also on file: Guar Gum is rated "Possibly Effective" for Constipation, Irritable bowel syndrome (IBS).
  • Also on file: Black Psyllium is rated "Insufficient Reliable Evidence To Rate" for Diarrhea.

Pectin and guar gum both have some evidence supporting use for high cholesterol (hypercholesterolemia) — the data rates them as possibly effective. Guar gum is also possibly effective for irritable bowel syndrome, high blood pressure, and constipation.

Marshmallow root, however, lacks reliable evidence for the conditions listed in the data we hold, including sore throat, diarrhea, and skin conditions like eczema — the evidence is insufficient to rate it. Oat bran and psyllium effectiveness information is not in our data.

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

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

Pectin is generally well tolerated in the amounts found in food and typical supplements, though concentrated supplement safety during pregnancy and breastfeeding has not been well studied — check with your doctor if you're pregnant or nursing. The most common side effects from pectin are mild: diarrhea, gas, loose stools, and cramping.

Rarely, some people experience allergic reactions, including severe ones (anaphylaxis) in sensitive individuals. Guar gum is generally well tolerated as a food but must be taken with plenty of water to avoid choking or blockage; gastrointestinal side effects like bloating, gas, and loose stools are common and usually mild if you start with small doses.

Pregnancy and lactation safety for guar gum supplements specifically has not been well studied. Marshmallow root is generally well tolerated for short-term use, but it's best avoided during pregnancy and breastfeeding because safety data are limited.

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

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?
  • 4 of the 4 matched ingredients can interact with medications — Black Psyllium, Pectin, Marshmallow, Guar Gum.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; heart-rhythm medications; lithium.
  • For scale: 2,050 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 this product, check with your doctor or pharmacist if you use lithium (mood stabilizer), digoxin or other heart medications, lovastatin or other cholesterol drugs, tetracycline or penicillin antibiotics, metformin or other diabetes medications, birth-control pills containing ethinyl estradiol, or blood thinners or antiplatelet drugs. These are the medication types most affected by ingredients in this formula, and absorption or levels may change.

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 fiber formula may help with cholesterol and constipation, but it can reduce how your body absorbs several important medications — especially digoxin, penicillin, metformin, tetracycline antibiotics, and lovastatin — and it may raise lithium levels. If you take any regular medications, especially heart, antibiotic, diabetes, or mood-stabilizing drugs, discuss this product with your doctor or pharmacist before you start.

The most common side effects are gas, bloating, and loose stools, especially at first.

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

Assessment coverage: 4 of 6 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 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 CVS Health
Net contents 112 Capsule(s)
Market status On market
Date entered into DSLD Jul 25, 2017
DSLD ID 76540
Product type Botanical With Nutrients
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegetarian, Adult (18 - 50 Years), Dairy Free, Sugar 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 CVS Health, 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 Root Extract0 NP--
Oat Bran0 NP--
Pectin0 NP--
Psyllium0 NP--
Guar Gum seed extract0 NP--
Proprietary Fiber Blend3.4 Gram(s)--

Other ingredients: Cellulose, Vegetable Capsule, 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.
Formula

CVS Health Fiber Formula contains fiber and herbs that absorb and eliminate toxins and supports colon function.

Fiber & herbs

General Statements

Fiber is effective only when fully dispersed in the colon to adhere to and eliminate toxins and enhance the removal of waste products.

That’s important, since detoxification products containing clay can deplete the body of healthy minerals, and often contain high levels of lead and other toxins.

Not for individual sale

~ Absorbs & eliminates toxins ~ Supports colon function

Brand IP Statement(s)

True Dispersion technology ensures the fiber is completely released and dispersed throughout the colon through cleansing.

CVS Quality Money back guaranteed

2015 CVS/pharmacy

Formulation

This is a clay-free formula.

Contains no sugar, salt, yeast, wheat, soy, dairy products, artificial colors, flavors, preservatives or ingredients of animal origin.

~ Clay-free formula

~ Vegetarian

Precautions

Caution: Take this product with at least 8 oz. of water. Taking without enough water may cause choking. Do not take this product if you have difficulty swallowing. If you experience chest pain, vomiting, or difficulty swallowing or breathing after taking this product, seek immediate medical attention.

Do not use if pregnant or nursing. If taking any medications, consult healthcare professional before use.

Suggested/Recommended/Usage/Directions

Recommendation: For 14 days, take four capsules in the morning and four at night with eight ounces of water. Or, may be taken as eight capsules at night with eight ounces of water.

General

LS98457CV . A03 BLK845A

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.

FDA Statement of Identity

Dietary Supplement

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

See for yourself

Fiber Formula by CVS Health 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 CVS Health

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

3.4 Gram(s) per serving

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

Interaction report

Fiber Formula by CVS Health 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
2,049Drugs
2,031 Moderate 18 Minor

Ingredients driving the most interactions

Marshmallow Root Extract 2,040
Dietary Fiber 2,025
Guar Gum seed extract 2,025
Pectin 23

Individual Drug Interactions

The ingredients in Fiber Formula interact with 2,049 drugs. Click any drug to see the details.

4 of the 6 ingredients in Fiber Formula interact with drugs. Each result below shows which ingredient is responsible. Marshmallow Root Extract Dietary Fiber Guar Gum seed extract 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 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 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 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 seed extract 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.

CVS Health

See all CVS Health products
Name
CVS Pharmacy, Inc.
Street Address
One CVS Drive
City
Woonsocket
State
RI
ZipCode
02895
Phone Number
1-800-746-7287
Web Address
www.cvs.com
Pharmacist Counseling Corner

Fiber Formula by CVS Health: Common Questions

Does Fiber Formula by CVS Health interact with any medications?
Yes. Based on its ingredients, Fiber Formula has a known interaction with 2,049 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.
Is marshmallow root in this formula safe during pregnancy?
No — the safety data advise against it. There isn't enough reliable information to know whether marshmallow root is safe when you're pregnant, so it's best avoided. Talk with your doctor or pharmacist about whether this product is right for you.
What are the most common side effects I might notice?
The fiber ingredients — especially guar gum and pectin — commonly cause bloating, gas, loose stools, and mild cramping, particularly when you first start. These effects usually improve if you begin with a small dose and increase it gradually. Drinking plenty of water with each dose helps too.
Can this product help with high cholesterol?
Possibly. Both pectin and guar gum in this formula are rated possibly effective for high cholesterol based on current evidence. Results vary from person to person, and it works best alongside a healthy diet and exercise.
Why do I need to take this product away from my other medications?
Several ingredients in this formula — marshmallow root, pectin, and guar gum — can coat the stomach or slow how your body absorbs other drugs, making them less effective. Taking this product 30–60 minutes after your regular medications helps keep them from interfering with each other.
Is oat bran in this formula safe? Does it interact with medications?
We don't hold safety or interaction data for oat bran in our system, so we can't answer that directly. Ask your doctor or pharmacist if you have specific concerns about this ingredient.
What if I'm breastfeeding — is this product safe?
Safety information for supplement amounts of these ingredients while breastfeeding is limited. Pectin from food is likely fine, but concentrated supplements and marshmallow root are best avoided unless your doctor says otherwise. Talk with your doctor or pharmacist about your situation.

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 →
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 60 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
  8. Albert KS, Welch RD, DeSante KA, et al. Decreased tetracycline bioavailability caused by a bismuth subsalicylate antidiarrheal mixture. J Pharm Sci 1979;68:586-8. PubMed
  9. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  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
  1. Gin H, Orgerie MB, Aubertin J. The influence of Guar gum on absorption of metformin from the gut in healthy volunteers. Horm Metab Res 1989;21:81-3.
  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
  3. Malo JL, Cartier A, L'Archeveque J, et al. Prevalence of occupational asthma and immunologic sensitization to guar gum among employees at a carpet-manufacturing plant. J Allergy Clin Immunol 1990;86:562-9. PubMed
  4. Lagier F, Cartier A, Somer J, et al. Occupational asthma caused by guar gum. J Allergy Clin Immunol 1990;85:785-90.
  5. Lewis JH. Esophageal and small bowel obstruction from guar gum-containing diet pills: analysis of 26 cases reported to the FDA. Am J Gastroenterol 1992;87:1424-8.
  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
  7. Superko HR, Haskell WL, Sawrey-Kubicek L, Farquhar JW. Effects of solid and liquid guar gum on plasma cholesterol and triglyceride concentrations in moderate hypercholesterolemia. Am J Cardiol 1988;62:51-5. PubMed
  8. 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
  9. Groop PH, Aro A, Stenman S, Groop L. Long-term effects of guar gum in subjects with non-insulin-dependent diabetes mellitus. Am J Clin Nutr 1993;58:513-8. PubMed
  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 →

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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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