Supplements

Psyllium

Updated · 26 sources

Psyllium is the husk of the seed of Plantago ovata, a soluble fiber that swells into a thick gel in water. In the US it is an over-the-counter (OTC) bulk-forming laxative, sold under brands such as Metamucil and many store labels. It is also a fiber supplement and food ingredient, and it is one of only two soluble fiber sources named in FDA’s heart disease claim rule, alongside beta-glucan from oats and barley.

In a meta-analysis of 28 randomized trials, a median dose of about 10 g/day lowered LDL cholesterol by 0.33 mmol/L (≈13 mg/dL). No trial has shown that it prevents heart attacks or deaths, so that benefit is inferred from cholesterol. The main acute danger is mechanical: taken with too little fluid, it can swell and block the throat or esophagus. Lead contamination is also documented in some products.

This page summarizes what FDA, the European Medicines Agency (EMA), clinical guidelines and randomized trials report. It is for education only and is not medical advice.

Property Detail
Type Soluble, gel-forming fiber; OTC laxative ingredient, dietary supplement and food ingredient
Also called Psyllium husk, ispaghula, blond psyllium; Metamucil is the best-known brand
Route and forms Oral: powders, capsules, wafers and fortified foods
US laxative dose (FDA monograph M007) Age 12 and over: up to 30 g/day in doses of 2.5–7.5 g. Ages 6 to under 12: up to 15 g/day in doses of 2.5–3.75 g. Under 6: consult a doctor
Typical product strength About 3.4 g of husk per Metamucil packet; about 0.52 g per capsule in a store-brand capsule
FDA heart claim amount 7 g/day or more of soluble fiber from psyllium husk
Doses in cited trials Median about 10.2 g/day (lipids); 10–15 g/day in most other trials cited here
Laxative onset (US labeling) 12–72 hours
Half-life Not applicable; it acts inside the gut and is not absorbed as a drug
WADA status Not named on the 2026 Prohibited List

What it is

Psyllium comes from the outer coat of the seed. FDA’s health claim rule defines eligible husk as the dried seed coat of Plantago ovata (blond or Indian psyllium), P. indica or P. psyllium, at 95% purity or higher (21 CFR 101.81).

The husk is not uniform. Researchers who separated it into fractions found that a gel-forming fraction, about 55% of the husk, is poorly fermented and raises stool moisture and fecal bile acid excretion. A smaller viscous fraction (under 15%) is rapidly fermented, and an alkali-insoluble fraction is not fermented (Marlett & Fischer, Proc Nutr Soc 2003).

The active fraction is a highly branched arabinoxylan: a xylose backbone with side chains containing arabinose and xylose. Cereal arabinoxylans are extensively fermented, while this one largely resists gut bacteria. That matters because fibers fermented in the colon lose their water-holding capacity and produce gas (ACG excerpt).

How it works in the body

Psyllium is only partly dissolved in water, so it hydrates and swells into a mucilage. Human digestive enzymes cannot break the bonds between its sugars, so it is not taken up as a nutrient and has no meaningful half-life (EMA monograph 2013). Its effects are physical:

  • Small intestine. The gel makes gut contents more viscous, slowing the breakdown and absorption of nutrients (Gibb et al., J Am Assoc Nurse Pract 2023). This is the proposed basis for the glucose effect.
  • Cholesterol. Fractionation work links the gel fraction to more bile acid lost in stool, which is proposed to lower blood cholesterol (Marlett & Fischer, Proc Nutr Soc 2003).
  • Colon. The swollen mass adds volume, which triggers defecation, and forms a lubricating layer that eases passage (EMA monograph 2013).

The same swelling explains the main hazard: if it hydrates in the wrong place, it can form an obstruction.

Regulatory status

OTC laxative

FDA regulates psyllium laxatives under OTC Monograph M007, a final administrative order posted in May 2023. It limits the use statement to relief of occasional constipation, states that the product generally produces a bowel movement in 12 to 72 hours, and sets the doses in the table above. Its general warnings cover abdominal pain, nausea or vomiting, a sudden change in bowel habits lasting 2 weeks, rectal bleeding, and use for longer than 1 week unless directed by a doctor (FDA M007). Many trials below ran longer than that, under study conditions.

Granular psyllium is treated differently. In 2007 FDA found granular forms not generally recognized as safe and effective, because the required warnings and directions were judged inadequate for them. These forms need an approved new drug application (21 CFR 201.319).

FDA heart health claim

In February 1998, responding to a petition from Kellogg, FDA extended its soluble fiber health claim to psyllium husk (63 FR 8103). One model wording in the regulation reads, with the psyllium details filled in:

“Diets low in saturated fat and cholesterol that include 7 grams of soluble fiber per day from psyllium husk may reduce the risk of heart disease. One serving of [name of food] provides ___ grams of this soluble fiber.”

The claim must say “may” or “might” and cannot state any degree of risk reduction. A qualifying food must supply at least 1.7 g of soluble fiber per standard serving and meet low-fat, low-saturated-fat and low-cholesterol requirements (21 CFR 101.81). Foods with dry or incompletely hydrated husk must carry a notice about liquid and choking (21 CFR 101.17).

One store-brand label states that a 3.4 g serving provides 2.4 g of soluble fiber, with directions for three servings a day (DailyMed). That is about 7 g of soluble fiber from 10.2 g of husk, matching the median dose in the lipid trials.

The claim concerns diet and disease risk; it is not an FDA approval to treat high cholesterol. Metamucil packaging statements such as “appetite control” carry the standard disclaimer that FDA has not evaluated them (Metamucil label).

Europe

EMA’s herbal medicines committee recognizes ispaghula husk as well established for constipation at 7–11 g/day, and as an add-on to diet in high cholesterol or constipation-predominant irritable bowel syndrome at 7–20 g/day. It says use for high cholesterol requires medical supervision (EMA monograph 2013).

What the research shows

LDL, non-HDL and apoB

The most complete analysis for these three markers pooled 28 randomized trials lasting at least 3 weeks, with 1,924 people with or without high cholesterol (Jovanovski et al., Am J Clin Nutr 2018). Non-HDL cholesterol is all cholesterol except HDL. ApoB is a protein found on each atherogenic particle.

Marker Mean difference vs control (95% CI) Approximate conversion GRADE certainty
LDL cholesterol −0.33 mmol/L (−0.38 to −0.27) ≈ −13 mg/dL Moderate
Non-HDL cholesterol −0.39 mmol/L (−0.50 to −0.27) ≈ −15 mg/dL Moderate
ApoB −0.05 g/L (−0.08 to −0.03) −5 mg/dL High

EMA separately cites an LDL reduction of about 7% in mild to moderate high cholesterol, and states that studies of cardiovascular events and total mortality are not available (EMA monograph 2013). We found no later randomized outcome trial, so any effect on heart disease is inferred from the lipid change rather than measured.

Added to statins

Three sets of data address psyllium on top of a statin:

Study Who Arms Result
Moreyra et al., Arch Intern Med 2005 68 patients; blinded, placebo-controlled Simvastatin 10 mg + placebo; simvastatin 10 mg + psyllium 15 g/day; simvastatin 20 mg + placebo At 8 weeks, LDL fell 55 mg/dL on 10 mg alone and 63 mg/dL with psyllium (P = .03). The fall on 20 mg alone was the same as with 10 mg plus psyllium
Jayaram et al., J Indian Med Assoc 2007 100 adults with high cholesterol; 97 completed Atorvastatin 10 mg alone, or with isapgol (psyllium) powder 5.6 g twice daily LDL fall at 8 weeks 20.5% vs 16.0% (not significant); at 12 weeks 31.4% vs 22.8% (P under .05)
Brum et al., Am J Cardiol 2018 Meta-analysis of 3 randomized trials lasting 4–12 weeks Statin plus psyllium vs statin alone Significant advantage (P = .001), described as equivalent to doubling the statin dose

Some context:

  • The evidence is small and short-term, and none of these reports gives cardiovascular events as an outcome.
  • Three of the five Brum authors worked for Procter & Gamble, which markets Metamucil, and the abstract gives no pooled LDL figure.
  • In Moreyra, triglycerides and HDL did not change significantly. The Jayaram abstract describes no placebo.
  • We found no randomized trial of psyllium added to rosuvastatin or to ezetimibe.

In Moreyra, 10 mg of simvastatin alone lowered LDL by 55 mg/dL and psyllium added 8 mg/dL. For drug and other options, see atorvastatin, rosuvastatin, ezetimibe and red yeast rice.

Blood sugar

Two meta-analyses of glycemic control report quite different figures for fasting glucose, largely because they cover different people:

Analysis Population HbA1c change Fasting glucose change
Gibb et al., Am J Clin Nutr 2015 People being treated for type 2 diabetes, in multiweek studies with psyllium dosed before meals −0.97% (P = .048) −37.0 mg/dL (P under .001)
Gholami et al., BMC Endocr Disord 2024 19 randomized trials, 962 adults; not restricted to diabetes −0.75 (95% CI −1.21 to −0.29) −6.89 (95% CI −10.62 to −3.16), unit not stated; likely mg/dL

Gibb’s team found that the benefit tracked baseline glucose: no significant lowering with normal glucose, modest improvement in prediabetes and the largest effect in treated type 2 diabetes. That pattern likely helps explain why an estimate not limited to diabetes shows a much smaller fasting glucose change. Gibb’s authors included Procter & Gamble employees, and the search included the company’s clinical records.

The Gholami authors declared no competing interests and rated the HbA1c and fasting glucose evidence as moderate certainty. They found no significant HbA1c effect below 10 g/day and no significant change in insulin.

The largest effects came in people already being treated, so these results do not show that psyllium can replace diabetes drugs. We found no randomized human trial focused on the combination with metformin. EMA says people with diabetes should use it under medical supervision because their medication may need adjusting (EMA monograph 2013).

Constipation

  • Meta-analysis. Across 16 randomized trials with 1,251 adults with chronic constipation, 66% responded to fiber and 41% to control (RR 1.48; 95% CI 1.17–1.88). Psyllium was one of two fibers with significant effects. The authors favored psyllium, more than 10 g/day and at least 4 weeks, but warned of considerable variation between trials. Flatulence was more common with fiber (van der Schoot et al., Am J Clin Nutr 2022).
  • Guideline. The 2023 American Gastroenterological Association and American College of Gastroenterology guideline makes a conditional recommendation for fiber on low-certainty evidence, and says only psyllium among the reviewed fibers appears effective. Its stronger recommendations went to other agents, including polyethylene glycol. Its psyllium estimate rests on 3 trials from 1986 to 1995, one using a combination with celandine and aloe vera: 2.32 more spontaneous bowel movements per week (95% CI 0.86–3.79) (Chang et al., Gastroenterology 2023).

Irritable bowel syndrome

  • Meta-analysis. A 2026 review of 30 placebo-controlled trials (1,904 adults) found clinical response in 52% on fiber vs 44% on control across the 16 trials reporting it (RR 1.21; 95% CI 1.03–1.41), with a significant result for psyllium specifically (RR 1.53; 95% CI 1.06–2.19). Overall symptom scores did not improve significantly across fibers (SMD −0.25; 95% CI −0.67 to 0.17) (Staudacher et al., Gastroenterology 2026).
  • Primary care trial. In 275 adults given 10 g/day of psyllium, bran or placebo for 12 weeks, more responded to psyllium than placebo in month 1 (57% vs 35%) and month 2 (59% vs 41%). Symptom severity fell by 90 points vs 49 at 3 months (P = .03). Quality of life did not differ, and only 64% of the psyllium group finished (Bijkerk et al., BMJ 2009).
  • Guideline. The American College of Gastroenterology states: “We suggest that soluble, but not insoluble, fiber be used to treat global IBS symptoms,” graded as a strong recommendation on moderate-quality evidence (Lacy et al., Am J Gastroenterol 2021; ACG excerpt).

Body weight

Weight results conflict more than any other outcome here:

Analysis Population Weight change vs control Other measures
Gibb et al. 2023 6 studies, 354 adults with overweight or obesity; dosed before meals; mean 10.8 g/day for 4.8 months −2.1 kg (95% CI −2.6 to −1.6) BMI −0.8 kg/m²; waist −2.2 cm
Shahinfar et al., Pharmacol Res 2023 Network analysis of 111 trials of 18 supplements in adults with overweight or obesity −3.70 kg (95% CI −5.18 to −2.22) Authors describe the effects as small; moderate certainty
Darooghegi Mofrad et al., Crit Rev Food Sci Nutr 2020 22 randomized trials in adults −0.28 kg (95% CI −0.78 to 0.21), not significant BMI and waist not significant
Gholami & Paknahad, J Health Popul Nutr 2025 27 randomized trials in adults +3.57 kg (95% CI 1.43 to 5.72) BMI −0.06 and waist +0.72 cm, both not significant

The two analyses showing weight loss were limited to people with overweight or obesity, and one was written by Procter & Gamble employees. The two broader analyses found no loss. The 2025 gain is hard to interpret, because more than 3.5 kg gained with an unchanged BMI is difficult to reconcile; its authors call it paradoxical and urge caution. Psyllium may help modestly in overweight adults, but it is not an established weight-loss treatment, and neither the FDA laxative monograph nor the heart claim covers weight loss.

Use alongside anabolic steroids

Anabolic steroids can worsen lipids, as described on the oxandrolone page. We found no trial of psyllium in people using them. The statin-combination trial above found no significant change in HDL, so the available data do not suggest psyllium would correct a steroid-related fall in HDL.

Side effects and risks

Choking and esophageal obstruction

FDA states that esophageal obstruction and asphyxiation have been associated with hydrophilic gums and mucilloids, including psyllium. It calls these significant risks when products are taken without adequate fluid or by people with esophageal narrowing or dysfunction or difficulty swallowing. Dry and incompletely hydrated OTC forms must carry this warning (21 CFR 201.319):

“Choking: Taking this product without adequate fluid may cause it to swell and block your throat or esophagus and may cause choking. Do not take this product if you have difficulty in swallowing. If you experience chest pain, vomiting, or difficulty in swallowing or breathing after taking this product, seek immediate medical attention.”

The required directions call for at least 8 ounces (a full glass) of water or other fluid per dose. EMA gives 30 mL of water per gram as an example of a sufficient amount and says not to take it immediately before bed (EMA monograph 2013).

Intestinal obstruction and impaction

EMA lists intestinal and esophageal obstruction and fecal impaction as possible effects, particularly with insufficient fluid, at an unknown frequency. Its contraindications include narrowing of the gastrointestinal tract, esophageal disease, existing or potential bowel blockage, paralysis of the intestine, megacolon, difficulty swallowing, undiagnosed rectal bleeding and a sudden change in bowel habit lasting more than 2 weeks. It advises medical supervision with medicines that slow gut movement, such as opioids, and in frail or older patients (EMA monograph 2013).

Allergy

Metamucil’s label carries an allergy alert for people sensitive to inhaled or ingested psyllium (Metamucil label). Reactions range from upper airway symptoms on inhalation to anaphylaxis on ingestion. One published case described fatal anaphylaxis in a 42-year-old woman, and the accompanying review found a clear link with atopy (a tendency to allergic disease). Sensitization is well described in healthcare and pharmaceutical workers who handle the powder (Khalili et al., Ann Allergy Asthma Immunol 2003).

Gut effects

Flatulence, bloating and abdominal distension are the usual reported complaints. EMA says flatulence generally disappears during treatment, and the Metamucil label describes starting with one dose a day and building up (Metamucil label).

Spacing from other medicines

The gel can delay absorption of other substances taken at the same time, and advice differs by regulator. Metamucil’s Drug Facts says to take it 2 or more hours before or after other drugs (Metamucil label). EMA says at least ½ to 1 hour apart and names minerals, vitamin B12, cardiac glycosides (such as digoxin), coumarin anticoagulants (such as warfarin), carbamazepine and lithium. It also advises medical supervision with thyroid hormones, such as T4, because the dose may need adjusting (EMA monograph 2013).

Other label points

The US label says to ask a health professional in pregnancy or breastfeeding; EMA notes limited data (under 300 pregnancy outcomes) (EMA monograph 2013). Sugar-free products may contain aspartame (25 mg of phenylalanine per Metamucil packet, relevant in phenylketonuria), and sweetened powders can contain added sugar (8 g per serving in one generic).

Quality and contamination

Lead in psyllium is documented mainly through independent product testing and California Proposition 65 records. We did not find a peer-reviewed market survey.

  • Independent testing. ConsumerLab, a subscription testing company, reports lead in all 9 psyllium products it tested, with excessive amounts in 4. The lowest had 1 mcg or less per 4 g of fiber and the highest up to 8.5 mcg per 4 g. Because intake depends on servings, the 4 excessive products ranged from 2.4 to 38.7 mcg at the maximum suggested daily amount (ConsumerLab review; ConsumerLab 2024). We saw only its free summaries, and the work is not peer reviewed.
  • Legal allegation. On July 27, 2026, the Environmental Research Center filed a 60-day notice against Procter & Gamble, alleging failure to warn about lead in eight Metamucil products. This is an allegation, not a finding. The notice lists no measured lead amounts, and the California Attorney General’s page lists no outcome so far (60-Day Notice 2026-03609).
  • Labels. Of 82 psyllium labels listed on DailyMed on November 8, 2026, 4 included a Proposition 65 lead warning, including one generic powder. A missing warning in that database does not show a product is lead-free.

These benchmarks differ. ConsumerLab describes the Proposition 65 warning level as more than 0.5 mcg per daily serving. FDA’s interim reference levels for dietary lead are higher, at 2.2 mcg/day for children and 8.8 mcg/day for females of childbearing age (FDA). The top ConsumerLab figure exceeds both. Because cholesterol trials used about three servings a day, lead per serving understates daily exposure.

Psyllium is not a controlled substance and is sold without a prescription. It is not named on the WADA 2026 Prohibited List. As with other supplements, a multi-ingredient product could still contain something undeclared.

Key takeaways

  • A gel-forming fiber that largely resists fermentation. Its gel thickens gut contents and carries water through the colon.
  • Modest, well-supported lipid effect. About 10 g/day lowered LDL by ≈13 mg/dL, non-HDL by ≈15 mg/dL and apoB by 5 mg/dL, but no outcome trial shows fewer cardiovascular events.
  • It adds to statins in small trials. In 68 patients, simvastatin 10 mg plus 15 g/day of psyllium matched simvastatin 20 mg over 8 weeks, but the evidence is short-term and partly industry-linked.
  • Clearest benefits in existing conditions. Results are strongest in type 2 diabetes, constipation and IBS, while weight results conflict.
  • Fluid is a safety issue. FDA requires a choking warning and directions for a full glass of fluid per dose.
  • Allergy, spacing and lead also matter. Allergic reactions have been fatal, labels advise separating it from other drugs, and independent testing and legal filings point to lead in some products.

Sources

  1. Food and Drug Administration. Health claims: soluble fiber from certain foods and risk of coronary heart disease. 21 CFR 101.81. eCFR; required label statement for psyllium foods, 21 CFR 101.17(f), eCFR; final rule, 63 FR 8103, February 18, 1998, Federal Register.
  2. Food and Drug Administration. Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids as active ingredients; required warnings and directions. 21 CFR 201.319. eCFR.
  3. Food and Drug Administration. Final Administrative Order (OTC000032). Over-the-Counter Monograph M007: Laxative Drug Products for Over-the-Counter Human Use. Posted May 2, 2023. FDA.
  4. Psyllium husk OTC labels. Metamucil, The Procter & Gamble Manufacturing Company, DailyMed; Select Brand smooth texture orange flavor, DailyMed; Psyllium Fiber, Marlex Pharmaceuticals, DailyMed.
  5. Committee on Herbal Medicinal Products. Community herbal monograph on Plantago ovata Forssk., seminis tegumentum. EMA/HMPC/199774/2012. May 14, 2013. EMA.
  6. Marlett JA, Fischer MH. The active fraction of psyllium seed husk. Proc Nutr Soc. 2003;62(1):207–209. PubMed.
  7. Jovanovski E, Yashpal S, Komishon A, et al. Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets, non-HDL cholesterol and apolipoprotein B: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2018;108(5):922–932. PubMed.
  8. Moreyra AE, Wilson AC, Koraym A. Effect of combining psyllium fiber with simvastatin in lowering cholesterol. Arch Intern Med. 2005;165(10):1161–1166. PubMed.
  9. Jayaram S, Prasad HB, Sovani VB, et al. Randomised study to compare the efficacy and safety of isapgol plus atorvastatin versus atorvastatin alone in subjects with hypercholesterolaemia. J Indian Med Assoc. 2007;105(3):142–145, 150. PubMed.
  10. Brum J, Ramsey D, McRorie J, et al. Meta-analysis of usefulness of psyllium fiber as adjuvant antilipid therapy to enhance cholesterol lowering efficacy of statins. Am J Cardiol. 2018;122(7):1169–1174. PubMed.
  11. Gibb RD, McRorie JW Jr, Russell DA, et al. Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis of data in euglycemic subjects, patients at risk of type 2 diabetes mellitus, and patients being treated for type 2 diabetes mellitus. Am J Clin Nutr. 2015;102(6):1604–1614. PubMed.
  12. Gholami Z, Clark CCT, Paknahad Z. The effect of psyllium on fasting blood sugar, HbA1c, HOMA IR, and insulin control: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials. BMC Endocr Disord. 2024;24(1):82. PubMed.
  13. Gibb RD, Sloan KJ, McRorie JW Jr. Psyllium is a natural nonfermented gel-forming fiber that is effective for weight loss: a comprehensive review and meta-analysis. J Am Assoc Nurse Pract. 2023;35(8):468–476. PubMed.
  14. Shahinfar H, Jayedi A, Torabynasab K, et al. Comparative effects of nutraceuticals on body weight in adults with overweight or obesity: a systematic review and network meta-analysis of 111 randomized clinical trials. Pharmacol Res. 2023;196:106944. PubMed.
  15. Darooghegi Mofrad M, Mozaffari H, Mousavi SM, et al. The effects of psyllium supplementation on body weight, body mass index and waist circumference in adults: a systematic review and dose-response meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. 2020;60(5):859–872. PubMed.
  16. Gholami Z, Paknahad Z. The effect of psyllium consumption on anthropometric indices: a systematic review and dose-response meta-analysis of randomized controlled trials. J Health Popul Nutr. 2025;44(1):372. PubMed.
  17. van der Schoot A, Drysdale C, Whelan K, Dimidi E. The effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2022;116(4):953–969. PubMed.
  18. Chang L, Chey WD, Imdad A, et al. American Gastroenterological Association-American College of Gastroenterology clinical practice guideline: pharmacological management of chronic idiopathic constipation. Gastroenterology. 2023;164(7):1086–1106. PubMed.
  19. Staudacher HM, Rucco V, Mancell S, et al. Fiber supplementation in irritable bowel syndrome: a systematic review and meta-analysis of randomized controlled trials. Gastroenterology. Published online August 14, 2026. PubMed.
  20. Lacy BE, Pimentel M, Brenner DM, et al. ACG clinical guideline: management of irritable bowel syndrome. Am J Gastroenterol. 2021;116(1):17–44. PubMed; ACG excerpt.
  21. Bijkerk CJ, de Wit NJ, Muris JW, et al. Soluble or insoluble fibre in irritable bowel syndrome in primary care? Randomised placebo controlled trial. BMJ. 2009;339:b3154. PubMed.
  22. Khalili B, Bardana EJ Jr, Yunginger JW. Psyllium-associated anaphylaxis and death: a case report and review of the literature. Ann Allergy Asthma Immunol. 2003;91(6):579–584. PubMed.
  23. ConsumerLab. Psyllium fiber supplements review. Updated October 8, 2026. ConsumerLab; news summary, February 29, 2024, ConsumerLab.
  24. Environmental Research Center, Inc. 60-Day Notice 2026-03609, filed July 27, 2026. California Attorney General.
  25. Food and Drug Administration. Lead in food and foodwares. FDA.
  26. World Anti-Doping Agency. The 2026 Prohibited List. WADA 2026 Prohibited List.