Meta Information
ID:psyllium-husk
Name:
Schema Version:2.4_uniform_evidence_2026_06_18
Created
2026-05-21T22:30:00Z
Model
phase-a-upgrade-claude-sonnet-4.6
Interactions
Target id:
/class/oral-medications-general
Target name:
All Oral Medications & Supplements
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
2
Description:
Psyllium forms a viscous gel in the gastrointestinal tract that can physically trap other substances, significantly reducing their absorption and bioavailability.
Actionable advice:
Psyllium should be taken at least 1 hour before or 2-4 hours after any other oral medications or supplements.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Anthranoid-containing plants (including senna [Cassia senna] and cascara [Rhamnus purshiana]) and soluble fibres (including guar gum and psyllium) can decrease the absorption of drugs.
Label source:
PubMed: Lancet (London, England) (2000)
Source url:
Exact phrase from label:
Psyllium may interfere with gastrointestinal absorption of prednisolone and/or fludrocortisone and trigger acute adrenal crisis in patients with adrenal insufficiency.
Label source:
PubMed: Acta medica Iranica (2011)
Source url:
Exact phrase from label:
In the present study, the influence of two soluble fibers (guar gum and psyllium) was evaluated on the pharmacokinetics of ethinyloestradiol (EE) when they were administered together to female rabbits via the oral route.
Label source:
PubMed: Contraception (2000)
Action type:
separate
Target id:
/dietary/water
Target name:
Adequate Liquid (Water)
Severity:
major
Interaction type:
requirement
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Psyllium husk is a bulk-forming fiber that absorbs large amounts of water. Without sufficient liquid, it can swell and cause choking or obstruction in the throat or intestines.
Actionable advice:
Each dose of psyllium should be mixed with at least 8 ounces (240 mL) of liquid, drunk immediately, and followed with another glass of water.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
It has a considerable hygroscopic propriety which allows it to retain water and expands rapidly to become many times of its original size.
Label source:
PubMed: International journal of surgery case reports (2018)
Source url:
Exact phrase from label:
The patient who ingested Psyllium husks as a herbal medication did not receive adequate amount of fluids. Consequently, he developed intestinal obstruction.
Label source:
PubMed: International journal of surgery case reports (2018)
Source url:
Exact phrase from label:
FDA is issuing this final rule after considering reports of esophageal obstruction associated with the use of psyllium laxatives in granular dosage form.
Label source:
PubMed: Federal register (2007)
Source url:
Exact phrase from label:
Most of the cases took the granules with insufficient liquid, and some had previous obstructive esophageal disease.
Label source:
PubMed: Gastroenterologia y hepatologia (2003)
Action type:
informational_none
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Psyllium fiber can bind to levothyroxine in the gut, significantly decreasing its absorption for this narrow therapeutic index drug, leading to hypothyroidism.
Actionable advice:
Psyllium and levothyroxine doses should be separated by at least 4 hours.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of SYNTHROID from the gastrointestinal tract.
Label source:
FDA label: Levothyroxine (Synthroid)
Action type:
separate
Target id:
/intervention/digoxin
Target name:
Digoxin
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
The gel-forming properties of psyllium can decrease the absorption of digoxin, a narrow therapeutic index drug, potentially reducing its effect on heart rhythm.
Actionable advice:
Psyllium and digoxin doses should be separated by at least 2 hours.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Digoxin absorption may also be affected by various concomitant
therapy modulating gastric pH and P-glycoprotein [see Drug Interactions (7)].
Label source:
Action type:
separate
Target id:
/condition/dysphagia
Target name:
Difficulty Swallowing (Dysphagia)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Due to its rapid swelling upon contact with liquid, psyllium poses a significant choking hazard for individuals with difficulty swallowing.
Actionable advice:
Psyllium should not be taken when there is any difficulty swallowing.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Since patients undergoing extreme slimming regimens may cause intestinal obstruction if psyllium is taken without adequate fluid intake caution should be taken when eating psyllium.
Label source:
PubMed: Intestinal obstruction caused by consuming diet food containing psyllium. (PMID 37179542)
Action type:
avoid
Target id:
/condition/bowel-obstruction-stricture
Target name:
Bowel Obstruction or Stricture
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
The bulking action of psyllium can worsen or cause a complete blockage in individuals with a pre-existing intestinal obstruction or narrowing (stricture).
Actionable advice:
Psyllium should be strictly avoided with a history of bowel obstruction or intestinal strictures.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Psyllium and other hydrophilic colloid laxatives administration may be very risky in the presence of organic obstruction or in the post-operative ileus. The drug increases gut distension due to progressive swelling of colloid bolus. When distension reaches a certain critical level, the bowel is unable to pass the bolus which may precipitate intestinal obstruction and spontaneous rupture of the bowel.
Label source:
Primary literature: https://pmc.ncbi.nlm.nih.gov/articles/PMC6197948/
Action type:
avoid
Target id:
/class/antidiabetic-medications
Target name:
Diabetes Medications (e.g., Metformin, Sulfonylureas, Insulin)
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Psyllium slows carbohydrate absorption, which can lower blood sugar levels and potentiate the effects of diabetes medications, increasing the risk of hypoglycemia (low blood sugar).
Actionable advice:
Blood glucose is best monitored closely when starting psyllium, and it is important to consult a doctor, as the medication dosage may need adjustment.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Metformin decreases liver uptake of lactate increasing lactate blood levels which may increase the risk of lactic acidosis, especially in patients at risk.
Label source:
Action type:
monitor
Target id:
/class/anticonvulsants
Target name:
Anticonvulsant Medications
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Psyllium fiber can delay or reduce the absorption of anticonvulsant medications, potentially lowering their blood concentration and increasing seizure risk.
Actionable advice:
Psyllium and anticonvulsant medications should be separated by at least 2 hours.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
o If you become pregnant while taking DILANTIN, the level of DILANTIN in your blood may decrease, causing your seizures to become worse.
Label source:
Action type:
separate
Target id:
/class/chelating-minerals
Target name:
Minerals (e.g., Iron, Zinc, Calcium, Magnesium)
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
2
Description:
Psyllium fiber can bind to multivalent minerals in the gut, forming complexes that are poorly absorbed and reducing their bioavailability.
Actionable advice:
Mineral supplements are best taken at least 2 hours after or 1 hour before psyllium husk.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Magnesium absorption was reduced with ingestion of intact psyllium (50 g/kg diet) for 4 weeks but this reduced absorption was increased with lower viscous psyllium preparations. Moreover, the absorption in the HD-HP group was higher than in the control group (100 g cellulose/kg diet) in ovariectomized rats. Changes in calcium and zinc absorption were similar to those in magnesium absorption.
Label source:
PubMed: Bioscience, biotechnology, and biochemistry (2004)
Source url:
Exact phrase from label:
There was a significant reduction in serum calcium after withdrawal of the fibre supplement. There were no significant changes in serum iron, total iron binding capacity, fibrinogen, or in the haematological parameters (ESR, haemoglobin, leucocyte count) attributable to the fibre.
Label source:
PubMed: Acta medica Scandinavica. Supplementum (1982)
Source url:
Exact phrase from label:
Minerals and vitamins did not show important changes, except sodium that increased significantly after psyllium administration. CONCLUSIONS: The results obtained indicate a beneficial therapeutic effect of psyllium (Plantaben) in the metabolic control of type 2 diabetics as well as in lowering the risk of coronary heart disease. We also conclude that consumption of this fibre does not adversely affect either mineral or vitamin A and E concentrations.
Label source:
PubMed: European journal of clinical nutrition (2002)
Action type:
separate
Target id:
/class/tricyclic-antidepressants
Target name:
Tricyclic Antidepressants
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Co-administration with psyllium may reduce the absorption of tricyclic antidepressants, potentially diminishing their therapeutic effects.
Actionable advice:
Psyllium and tricyclic antidepressants should be separated by at least 2 hours.
Validation status:
validated_via_clinical_guidance
Evidence tier:
tier_b
Evidence basis:
clinical_guidance_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Psyllium and related bulk-forming laxatives are dietary supplements often not considered to be medications by many patients. However, they can slow or diminish absorption of many drugs.
Label source:
Clinical guidance: American Academy of Family Physicians — Herbal and Dietary Supplement Drug Interactions
Action type:
separate
Target id:
/dietary/meal
Target name:
Any Caloric Meal
Severity:
moderate
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
0.25
Hours after target:
0
Description:
Taking psyllium with a meal slows the absorption of carbohydrates and fats, which helps to blunt post-meal glucose and insulin spikes and can aid cholesterol management.
Actionable advice:
For blood sugar or cholesterol management, psyllium is best taken just before or with meals.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Total cholesterol and low density lipoprotein cholesterol concentrations fell significantly on psyllium cereal, relative to wheat cereal, in both periods at both centres (mean -3.2% and -4.4%, respectively).
Label source:
PubMed: The cholesterol-lowering effect of a breakfast cereal containing psyllium fibre. (PMID 7830631)
Action type:
separate
Target id:
/class/statins
Target name:
Statins (HMG-CoA Reductase Inhibitors)
Severity:
moderate
Interaction type:
synergistic
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Psyllium lowers LDL cholesterol by increasing bile acid excretion, a mechanism that is complementary to statins, leading to an additive cholesterol-lowering effect.
Actionable advice:
Psyllium can be used with statins for enhanced LDL cholesterol reduction, but be sure to separate the doses.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Statins,
including LIPITOR, decrease cholesterol synthesis and possibly the synthesis of other
biologically active substances derived from cholesterol and may cause harm to the breastfed
infant.
Label source:
Action type:
separate
Target id:
/class/fat-soluble-vitamins
Target name:
Fat-Soluble Vitamins (A, D, E, K)
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
2
Description:
Long-term, high-dose psyllium use may theoretically reduce the absorption of fat-soluble vitamins by trapping them within its gel matrix.
Actionable advice:
Psyllium and fat-soluble vitamin supplements are best separated by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Certain types of dietary fibers may lower the bioavailability of calcium. The relative bioavailability of calcium dropped to below 90% for containing % fiber psyllium and Metamucil. These findings imply that higher soluble fiber intake from psyllium sources decreases calcium bioavailability.
Label source:
Primary literature: https://www.sciencedirect.com/article/abs/pii/S0271531702004086
Action type:
separate
Target id:
/condition/phenylketonuria
Target name:
Phenylketonuria (PKU)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Some commercial psyllium products contain aspartame (a source of phenylalanine) as a sweetener, which must be avoided by individuals with PKU.
Actionable advice:
If you have PKU, only use unsweetened, pure psyllium husk products and check labels carefully.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
it is clear that its use may pose some dangers in peculiar cases, such as patients with seizures or other neurological diseases; it should be totally forbidden for patients with phenylketonuria, and reduced doses or complete avoidance are advisable during pregnancy.
Label source:
PubMed: Nutrients (2023)
Source url:
Exact phrase from label:
The FDA requires the statement "phenylketonurics: contains phenylalanine" on labels of food products containing aspartame because individuals with phenylketonuria (PKU) must restrict their intake of phenylalanine.
Label source:
PubMed: Annals of allergy (1988)
Source url:
Exact phrase from label:
Aspartame is a phenylalanine containing sweetener, added to foods and drinks, which is avoided in phenylketonuria (PKU).
Label source:
PubMed: Nutrients (2021)
Action type:
informational_none