Fybogel (ispaghula husk)

Generic Name

Ispaghula husk (also known as psyllium husk)

Brand Names

Fybogel

Fybogel Orange

Fybogel Hi-Fibre

Fybogel Mebeverine (combination)

Metamucil (US)

Isogel

Regulan

Benefiber (some formulations)

Form available as granules for oral suspension and in sachets containing typically 3.5 g ispaghula husk per dose

Drug Class

Bulk-forming laxative

Soluble dietary fiber

Non-stimulant gastrointestinal agent

Mechanism of Action

Ispaghula husk is a natural plant-derived mucilage extracted from the outer layer of Plantago ovata seeds

When mixed with water, it forms a gel-like mass due to its high content of soluble polysaccharides

This gel increases the bulk and moisture content of stool

The increased volume stimulates peristalsis and facilitates regular bowel movements

It softens stool, improving consistency and reducing straining during defecation

Also used to normalize stool in both constipation and mild diarrhea due to its water-absorbing and gelling properties

It has prebiotic effects, favoring the growth of beneficial colonic bacteria

Indications

Relief of constipation, including in pregnancy

Maintenance of normal bowel function

Management of conditions requiring soft stools such as:

– Hemorrhoids

– Anal fissures

– After anorectal surgery

As adjunct in irritable bowel syndrome (IBS) with constipation

Adjunct in ulcerative colitis (mild to moderate)

Supportive dietary fiber supplement in low-fiber diets

Occasionally used in mild diarrhea to help bulk stool

Off-label/Alternative Uses

Adjunctive treatment in type 2 diabetes mellitus for mild glucose-lowering effect

Mild cholesterol reduction (lowers LDL slightly with long-term use)

Dosage and Administration

Adults and Children Over 12 Years

One sachet (3.5 g ispaghula husk) in approximately 150 ml of cold water

Taken 1–2 times daily, preferably after meals

Stir well and drink immediately

Followed by additional glass of water to ensure full hydration and reduce esophageal risk

Children 6–12 Years

Half to one sachet once or twice daily as advised by physician

Children under 6 Years

Not generally recommended unless advised by a specialist

Elderly

Same dose as adults

Ensure hydration and gradual initiation

Onset of Action

Typically 12 to 24 hours

May take up to 2–3 days for full effect

Pharmacokinetics

Not systemically absorbed

Acts locally within the gastrointestinal tract

Fermented partially by colonic bacteria into short-chain fatty acids

Non-toxic and generally not metabolized beyond intestinal flora interactions

Contraindications

Hypersensitivity to ispaghula or any product component

Sudden change in bowel habits persisting >2 weeks without medical assessment

Bowel obstruction or fecal impaction

Esophageal or gastrointestinal narrowing or motility disorders (e.g., achalasia)

Difficulty swallowing or risk of aspiration

Undiagnosed abdominal pain, nausea, or vomiting

Severe dehydration

Warnings and Precautions

Adequate fluid intake is essential to avoid intestinal blockage or esophageal obstruction

Should not be taken immediately before bedtime to avoid esophageal retention

Caution in individuals with diabetes (some formulations contain sugars)

Avoid in patients with known strictures, mega-colon, or at risk of bowel obstruction

May cause flatulence and bloating in the initial phase

Do not inhale powder — risk of sensitization or allergic bronchospasm

Adverse Effects

Common

Flatulence

Bloating

Abdominal cramping

Initial increase in bowel frequency

Uncommon to Rare

Esophageal or intestinal obstruction (if taken without sufficient fluid)

Allergic reactions: rash, rhinitis, bronchospasm, anaphylaxis (especially with powder inhalation)

Nausea or vomiting (rare)

Hypersensitivity reactions (especially in occupational settings involving powder exposure)

Pregnancy and Lactation

Pregnancy

Considered safe and commonly recommended for constipation in pregnancy

No teratogenic or embryotoxic effects reported

Does not affect uterine tone or hormonal pathways

Lactation

Safe to use during breastfeeding

No known effect on breast milk production or composition

Drug Interactions

Absorption Interference

May impair absorption of oral medications taken simultaneously (especially narrow therapeutic index drugs)

Administer other oral drugs at least 1 hour before or 4 hours after ispaghula husk

Drugs Affected

Thyroxine (levothyroxine)

Cardiac glycosides (digoxin)

Lithium

Iron supplements

Tricyclic antidepressants

Carbamazepine

Anticoagulants (warfarin, due to vitamin K changes via microbiota alteration)

Hypoglycemic Agents

May modestly lower postprandial blood glucose

Additive effect with oral antidiabetics (monitor glucose levels closely)

Monitoring Parameters

Bowel movement regularity and consistency

Flatulence or bloating severity

Signs of esophageal or intestinal obstruction (rare)

Tolerance and compliance

Blood glucose in diabetic patients if used adjunctively

Counseling Points

Mix each sachet in at least 150 ml of cold water and drink immediately

Follow each dose with an extra glass of water

Do not take just before bedtime

Allow 2–3 days for effect

Do not inhale powder — open sachets gently

Check labels for sugar content if diabetic

Do not use continuously for more than 1 week without consulting a healthcare professional

Space other oral medications 1 hour before or 4 hours after

Stop and seek medical attention if signs of allergy or bowel obstruction occur

Comparative Notes

Fybogel vs Lactulose

Fybogel softens and bulks stool without causing significant cramping

Lactulose acts osmotically and may cause more gas and cramping

Fybogel preferred for long-term bowel regulation

Lactulose often used for hepatic encephalopathy or acute constipation

Fybogel vs Senna

Fybogel acts gently and requires 1–3 days for effect

Senna is a stimulant laxative with faster onset (~6–12 hours)

Fybogel is suitable for chronic use

Senna should be used short-term due to potential for colonic nerve damage with long-term use

Fybogel vs Docusate Sodium

Both are stool softeners, but docusate acts more as a surfactant

Fybogel improves stool bulk and overall gut transit

Fybogel vs Loperamide (for diarrhea)

Fybogel absorbs excess fluid in mild diarrhea and normalizes stool consistency

Loperamide directly slows bowel motility and is more potent in severe diarrhea

Legal and Regulatory Status

Available over-the-counter (OTC)

Not classified as a prescription drug

Included in many national formularies

Widely considered a first-line treatment for mild to moderate constipation