Methylcellulose

Also called Citrucel, cellulose methyl ether, non-fermentable fiber, hydroxypropyl methylcellulose (HPMC).

Best grade B across 9 graded outcomes Other Last checked Oct 21, 2026

The short answer

From 12 sources

Methylcellulose is a non-fermentable fiber sold as a bulk laxative. Evidence for constipation comes from uncontrolled studies (grade D), and it did not beat placebo in a small IBS trial. A related form, hydroxypropyl methylcellulose, lowered LDL cholesterol by about 8 to 16% in randomized trials at 5 to 15 g/day.

Every graded outcome on this page

9 rows · line = participants

Grade BLDL cholesterolCholesteroln 160
Grade CTotal and LDL cholesterolCholesteroln 52
Grade DConstipation symptoms (stool frequency, consistency, ease of passage)Constipationn 538
Grade DIBS symptom severity and quality of lifeIBSn 135
Grade DComplete bowel movements, stool consistency and strainingConstipationn 42
Grade DBlood glucose and insulin after a mealBlood sugarn 31
Grade DEarly breath hydrogen after inulin (non-inferiority to psyllium)Gasn 30
Grade DColonic gas after a fermentable fiber (inulin)Gasn 22
Grade DLDL cholesterol on top of a statinCholesteroln 13
6 more graded outcomes, in the evidence chapter

Key facts

What it is: A cellulose derivative that forms a gel with water and is not fermented by gut bacteria^4,5
Constipation evidence: Uncontrolled studies only: 61% of 538 patients improved in a 1989 study; a 2003 caplet study had no control group^1,2
IBS: No difference from placebo on symptom severity in a 135-person exploratory trial³
Cholesterol (HPMC form): LDL fell about 12% at 5 to 7.5 g/day for 6 weeks in 160 adults, and 15% at 15 g/day in an 8-week trial^6,7
Choking warning: FDA requires dry gum laxatives, including methylcellulose, to carry a warning that taking them without enough fluid can block the throat¹⁰

What it is

Methylcellulose is a semi-synthetic, non-fermentable soluble fiber made from plant cellulose, sold as a bulk-forming laxative.

How it works

Proposed

Methylcellulose absorbs water and forms a gel that adds bulk and water to stool. Because gut bacteria do not ferment it, it does not produce gas itself. In human MRI studies it increased water in the small bowel and colon. Its relative HPMC also forms a viscous gel, and higher-viscosity grades lowered cholesterol more in one trial, which fits a viscosity-based effect.^4,5,7

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Methylcellulose forms compared

2 forms

Methylcellulose forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 forms	(laxative powders and caplets)	Hydroxypropyl methylcellulose (HPMC)
Absorption in people	Not absorbed; it passes through the gut and is not fermented by gut bacteria.^4,5	No head-to-head human data. It acts in the gut as a viscous gel; higher-viscosity grades lowered cholesterol more.⁷
GI tolerance	No adverse effects are described in the cited constipation abstracts; FDA requires a choking warning on dry gum laxatives taken without enough fluid.^1,2,10	Gastrointestinal adverse events did not differ from placebo at up to 7.5 g/day for 6 weeks.^6,7
Studied for	Constipation, IBS and gas from fermentable fiber	Cholesterol and blood sugar after meals

Methylcellulose (laxative powders and caplets)
Absorption in people
Not absorbed; it passes through the gut and is not fermented by gut bacteria.^4,5
GI tolerance
No adverse effects are described in the cited constipation abstracts; FDA requires a choking warning on dry gum laxatives taken without enough fluid.^1,2,10
Studied for
Constipation, IBS and gas from fermentable fiber
Hydroxypropyl methylcellulose (HPMC)
Absorption in people
No head-to-head human data. It acts in the gut as a viscous gel; higher-viscosity grades lowered cholesterol more.⁷
GI tolerance
Gastrointestinal adverse events did not differ from placebo at up to 7.5 g/day for 6 weeks.^6,7
Studied for
Cholesterol and blood sugar after meals

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

9 graded outcomes, largest study first

9 graded outcomes: 6 improved, 1 mixed, 2 no effect. The largest, a 1989 observational study of 538 people on constipation symptoms (stool frequency, consistency, ease of passage), found an improvement.

By sizeTable

1Constipation symptoms (stool frequency, consistency, ease of passage)

Improved · Grade D · Observational, 538 people, 1989

Patients with a history of constipation (fewer than three stools a week), USA

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Constipation symptoms (stool frequency, consistency, ease of passage)	Improved	538	Grade D · Observational, 1989	Patients with a history of constipation (fewer than three stools a week), USA
LDL cholesterol	Improved	160	Grade B · RCT, 1999	Adults with mild to moderate high LDL cholesterol on a Step I diet
IBS symptom severity and quality of life	No effect	135	Grade D · RCT, 2013	Adults aged 16 to 60 with IBS (Rome III) in UK primary care
Total and LDL cholesterol	Improved	52	Grade C · RCT, 2009	Adults with mildly high cholesterol (two trials: 12 and 40 participants)
Complete bowel movements, stool consistency and straining	Improved	42	Grade D · Open-label trial, 2003	Patients from colorectal surgical practices who had been advised to use fiber (USA)
Blood glucose and insulin after a meal	Improved	31	Grade D · Crossover RCT, 2007	Overweight or obese adults without diabetes (USA)
Early breath hydrogen after inulin (non-inferiority to psyllium)	No effect	30	Grade D · Crossover RCT, 2026	Healthy volunteers (UK)
Colonic gas after a fermentable fiber (inulin)	Mixed	22	Grade D · Crossover RCT, 2026	Healthy volunteers (UK)
LDL cholesterol on top of a statin	Improved	13	Grade D · Crossover RCT, 2009	Men and women with high cholesterol on stable statin therapy (USA)

Every graded row

9 rows

Form tested

Showing 9 of 9 outcomes. Human trials only.

Grade BLDL cholesterolCholesterolImprovedRCT
n 160 · 1999

Improved LDL cholesterol fell by about 12% from baseline at 5 and 7.5 g/day, significantly more than placebo or 2.5 g/day. HDL, triglycerides and gastrointestinal adverse events did not differ between groups.

Design: RCT, n = 160, 1999
Population: Adults with mild to moderate high LDL cholesterol on a Step I diet
Form: High-viscosity hydroxypropyl methylcellulose (HPMC)
Dose: 2.5, 5 or 7.5 g/day (vs placebo)
Duration: 6 weeks
Source: Reference 6 · PubMed 10569330 (opens PubMed)

Grade CTotal and LDL cholesterolCholesterolImprovedRCT
n 52 · 2009

Improved In the 8-week trial, LDL cholesterol fell 8% at 5 g/day and 15% at 15 g/day more than placebo; higher-viscosity grades worked better in the 1-week trial. Adverse effects were described as minimal.

Design: RCT, n = 52, 2009
Population: Adults with mildly high cholesterol (two trials: 12 and 40 participants)
Form: Medium-, high- and ultra-high-viscosity HPMC
Dose: 5 or 15 g/day
Duration: 1 week per grade (trial 1); 8 weeks (trial 2)
Source: Reference 7 · PubMed 17882138 (opens PubMed)

Grade DConstipation symptoms (stool frequency, consistency, ease of passage)ConstipationImprovedObservational
n 538 · 1989

Improved Stool frequency, consistency and ease of passage returned to normal, and 61% of patients were judged to have less constipation. Response did not differ by sex, age or diverticular disease.

Design: Observational, n = 538, 1989
Population: Patients with a history of constipation (fewer than three stools a week), USA
Form: Methylcellulose powder
Dose: 1 to 3 tablespoons a day
Duration: Not stated in the abstract
Source: Reference 1 · PubMed 2805023 (opens PubMed)

Grade DIBS symptom severity and quality of lifeIBSNo effectRCT
n 135 · 2013

No effect Neither methylcellulose nor mebeverine differed from placebo on IBS symptom severity or IBS quality of life at 6 or 12 weeks.

Design: RCT, n = 135, 2013
Population: Adults aged 16 to 60 with IBS (Rome III) in UK primary care
Form: Over-encapsulated methylcellulose
Dose: Not stated in the abstract
Duration: 6 weeks of medication, follow-up to 12 weeks
Source: Reference 3 · PubMed 23602047 (opens PubMed)

Grade DComplete bowel movements, stool consistency and strainingConstipationImprovedOpen-label trial
n 42 · 2003

Improved The share of complete bowel movements and normal-consistency stools rose and straining fell over 14 days; physicians rated more than 75% of responses very good or excellent.

Design: Open-label trial, n = 42, 2003
Population: Patients from colorectal surgical practices who had been advised to use fiber (USA)
Form: Methylcellulose caplets (500 mg each)
Dose: Average 3.1 caplets a day (about 1.6 g methylcellulose); 2 caplets twice daily advised
Duration: 2 weeks
Source: Reference 2 · PubMed 12582295 (opens PubMed)

Grade DBlood glucose and insulin after a mealBlood sugarImprovedCrossover RCT
n 31 · 2007

Improved Peak glucose was lower after both HPMC meals (7.4 vs 8.6 mmol/L), and peak insulin and 2-hour glucose and insulin areas were also lower.

Design: Crossover RCT, n = 31, 2007
Population: Overweight or obese adults without diabetes (USA)
Form: High-viscosity HPMC mixed into a breakfast meal
Dose: 4 or 8 g with a 75 g carbohydrate meal (vs 8 g cellulose)
Duration: Single meals, separated by at least 72 hours
Source: Reference 9 · PubMed 17259476 (opens PubMed)

Grade DEarly breath hydrogen after inulin (non-inferiority to psyllium)GasNo effectCrossover RCT
n 30 · 2026

No effect Psyllium reduced early breath hydrogen versus placebo, but methylcellulose was not shown to be non-inferior to psyllium.

Design: Crossover RCT, n = 30, 2026
Population: Healthy volunteers (UK)
Form: Methylcellulose gel formulated to match psyllium
Dose: Single dose co-administered with inulin (vs psyllium or maltodextrin)
Duration: Single dose, 24 hours of breath testing
Source: Reference 5 · PubMed 41636227 (opens PubMed)

Grade DColonic gas after a fermentable fiber (inulin)GasMixedCrossover RCT
n 22 · 2026

Mixed Methylcellulose and psyllium did not change total colonic gas over 6 hours, but both were linked to less colonic gas once the gels reached the colon (3 to 6 hours). 24-hour breath hydrogen did not differ between groups.

Design: Crossover RCT, n = 22, 2026
Population: Healthy volunteers (UK)
Form: Methylcellulose gel formulated to match psyllium
Dose: 15 g methylcellulose with 15 g inulin, single dose (vs psyllium or maltodextrin)
Duration: Single dose, 24 hours of MRI and breath testing
Source: Reference 4 · PubMed 42728685 (opens PubMed)

Grade DLDL cholesterol on top of a statinCholesterolImprovedCrossover RCT
n 13 · 2009

Improved LDL cholesterol fell 15.7% with HPMC versus 5.1% with control; total and non-HDL cholesterol and apo B also fell more. HDL and triglycerides did not differ.

Design: Crossover RCT, n = 13, 2009
Population: Men and women with high cholesterol on stable statin therapy (USA)
Form: HPMC in a lemonade drink
Dose: 2.5 g twice daily (5 g/day) vs control
Duration: 4 weeks per period
Source: Reference 8 · PubMed 19209184 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

Widely used, thinly tested

Methylcellulose has been sold for decades, but its constipation evidence in our sources is uncontrolled, and the one randomized IBS trial found no difference from placebo.^1,2,3

Gel alone did not match psyllium

A methylcellulose gel built to mimic psyllium did not match psyllium's slowing of inulin fermentation in a 30-person trial, which suggests psyllium's effect is not just about forming a gel.⁵

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from about 1.5 to 15 g/day: about 1.6 g/day of methylcellulose caplets for 2 weeks and 1 to 3 tablespoons of powder a day (constipation), 15 g as a single dose (gas studies), and 2.5 to 15 g/day of HPMC for 4 to 8 weeks (cholesterol).^1,2,4,6,7,8

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

What Methylcellulose meets

0 cited rows 2 tested together

Medicines 0

No medicine rows in our sources.

Methylcellulose0 medicines · 1 supplement

Supplements and foods 1

Tested together in a graded trial

Also cited: 2 tested together

InulinInulin page
- Tested together
  Colonic gas after a fermentable fiber (inulin). Graded on the Methylcellulose page; tested together is not a claim that they work better together.
- Tested together
  Early breath hydrogen after inulin (non-inferiority to psyllium). Graded on the Methylcellulose page; tested together is not a claim that they work better together.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Methylcellulose and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Methylcellulose.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

6 groups

Swallowing problems: FDA links dry gum laxatives, including methylcellulose, to esophageal blockage and choking when taken without enough fluid or by people with a narrowed esophagus or trouble swallowing.¹⁰
Bowel symptoms: The FDA-format label advises asking a doctor before use with a sudden change in bowel habits lasting two weeks, or with abdominal pain, nausea or vomiting, and stopping if constipation lasts more than 7 days or there is rectal bleeding.¹¹
Phenylketonuria: The sugar-free powder contains phenylalanine (48.6 mg per adult dose), according to its label.¹¹
Children: The label gives separate amounts for ages 6 to 11 and says children under 6 should see a doctor first. The cited trials enrolled adults only.^11,3
Pregnancy and breastfeeding: The cited trials did not include pregnant or breastfeeding women, and LactMed has no methylcellulose record. For psyllium, another bulk fiber, LactMed notes it is not absorbed and so cannot enter breastmilk; methylcellulose is a non-fermentable fiber that an MRI study tracked into the colon as a gel, but it has not been studied in breastfeeding.^3,12,4
Medicines: No published drug-interaction studies were found, and the Citrucel label lists no drug interactions or dose-spacing directions, so interaction data are limited.¹¹

Reading the label, and the cost per dose

Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.

How to read the label

3 checks

Methylcellulose vs HPMC

Laxative products contain methylcellulose. The cholesterol trials used hydroxypropyl methylcellulose (HPMC), a different chemical grade, so their results do not carry over to laxative products.^1,6,7

Fluid warning

FDA-required labeling on dry gum laxatives warns that taking the product without enough fluid may cause choking.¹⁰

Grams of methylcellulose per dose

Citrucel powder lists 2 g of methylcellulose per heaping or rounded tablespoon; caplets list 500 mg each. The sugar-free powder adds phenylalanine and the orange powder adds sugar calories.^11,2

Have the bottle? Photograph its Supplement Facts panel and see each line, methylcellulose included, beside the doses and forms the trials used in Label X-Ray.

Cost per studied dose, without the sales pitch

Your numbers, no product data

Price paid ($)Servings per containerMethylcellulose per serving (mg)

Compare against

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Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

8 answers

Does methylcellulose help constipation?

Uncontrolled studies reported better stool frequency and consistency, including 61% of 538 patients in a 1989 study, but no placebo-controlled constipation trial appears in our sources.^1,2

Does methylcellulose lower cholesterol?

Trials of hydroxypropyl methylcellulose (HPMC), a related form, lowered LDL cholesterol by about 8 to 16% at 5 to 15 g/day. These trials did not test laxative methylcellulose products.^6,7,8

Does methylcellulose help IBS?

In a 135-person exploratory UK trial, methylcellulose did not differ from placebo on IBS symptom severity or quality of life.³

Does methylcellulose cause gas?

It is not fermented by gut bacteria, so it should not produce gas itself. With inulin, a methylcellulose gel was linked to less colonic gas once it reached the colon in one MRI study.^4,5

Is methylcellulose safe?

Tolerance was good in the cited trials. FDA requires a warning that dry gum laxatives taken without enough fluid can swell and block the throat.^6,10

How much methylcellulose is in a dose?

Citrucel powder lists 2 g per heaping or rounded tablespoon, and caplets list 500 mg each. The caplet study averaged about 1.6 g a day.^11,2

Does methylcellulose interact with medicines?

No published interaction studies were found, and the Citrucel label lists no drug interactions or spacing directions. Interaction data are limited, so a pharmacist is the best person to ask about a specific medicine.¹¹

Is methylcellulose safe in pregnancy or while breastfeeding?

It has not been studied in pregnancy or breastfeeding. LactMed has no methylcellulose record; for psyllium, a similar bulk fiber, it notes the fiber is not absorbed and cannot enter breastmilk. Methylcellulose is a similar non-fermentable fiber that an MRI study tracked into the colon, but no breastfeeding data exist.^12,4

Sources

12 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

12 sources

1The effect of methylcellulose on symptoms of constipation.Observational Clin Ther, 1989 · PMID 2805023
2Patient and physician evaluation of a new bulk fiber laxative tablet.Open-label trial Gastroenterol Nurs, 2003 · PMID 12582295
3Management of irritable bowel syndrome in primary care: the results of an exploratory randomised controlled trial of mebeverine, methylcellulose, placebo and a self-management website.RCT BMC Gastroenterol, 2013 · PMID 23602047
4Clinical Trial: Randomised Placebo-Controlled Trial of Methylcellulose and Psyllium Gels on Inulin-Induced Colonic Gas.Crossover RCT Aliment Pharmacol Ther, 2026 · PMID 42728685
5A randomised, placebo-controlled trial in healthy humans of modified cellulose or psyllium evaluating the role of gelation in altering colonic gas production during inulin co-administration.Crossover RCT Food Funct, 2026 · PMID 41636227
6Cholesterol lowering with high-viscosity hydroxypropylmethylcellulose.RCT Am J Cardiol, 1999 · PMID 10569330
7Hydroxypropylmethylcellulose significantly lowers blood cholesterol in mildly hypercholesterolemic human subjects.RCT Eur J Clin Nutr, 2009 · PMID 17882138
8Hydroxypropylmethylcellulose lowers cholesterol in statin-treated men and women with primary hypercholesterolemia.Crossover RCT Eur J Clin Nutr, 2009 · PMID 19209184
9High-viscosity hydroxypropylmethylcellulose blunts postprandial glucose and insulin responses.Crossover RCT Diabetes Care, 2007 · PMID 17259476
1021 CFR 201.319 Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including methylcellulose) as active ingredients; required warnings and directionsLabel eCFR (U.S. Food and Drug Administration), 2026 · ecfr.gov
11Citrucel (methylcellulose) powder for solution: OTC drug labelLabel DailyMed (U.S. National Library of Medicine), 2026 · dailymed.nlm.nih.gov
12Psyllium. Drugs and Lactation Database (LactMed)Database National Institute of Child Health and Human Development (NCBI Bookshelf), 2021 · ncbi.nlm.nih.gov

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026who should be careful, label guide, faq	Checked for interactions: no published PK or case-report interactions found on PubMed, and the Citrucel powder label (DailyMed, set id 9d5f2244) and 18 other DailyMed methylcellulose labels carry no drug-spacing statement, so interactions stay empty and a limited-data note was added. Added label-sourced cautions (bowel symptoms, phenylketonuria, children under 6), pregnancy and breastfeeding note citing LactMed (psyllium, NBK501346; no methylcellulose record), a label-guide step and three FAQs. No 2023–2026 meta-analysis or new RCT found. Fact-checked against the sources; corrected: removed an unsourced claim that methylcellulose is not absorbed.	Writer: Kymata Health EditorialTrigger: A–Z page audit
Oct 17, 2026all	First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for every cited row.	Writer: Kymata Health EditorialTrigger: new page
Oct 17, 2026all	Adversarial review pass: every evidence row's numbers machine-checked against its PubMed abstract, retraction and erratum flags checked for all PMIDs, unverified country and affiliation details removed, and claims not supported by the cited abstracts reworded or dropped.	Writer: Kymata Health EditorialTrigger: review

Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.

Methylcellulose

Medicines 0

Supplements and foods 1

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