PEG 3350
MIRALAX
“Peg man Goes lightly”
What it isOsmotic laxative that retains water in the lumen; constipation and bowel preparation.
Why this oneLack of bacterial fermentation means less gas than lactulose, helping make it the preferred chronic osmotic laxative.
What limits itOnset takes one to three days; large-volume bowel preparation can shift electrolytes in frail patients or kidney disease.
Pearls
- IBS-C: more bowel movements, but no relief of pain or global symptoms.
PEG 3350 prescription history
Animated chart of estimated U.S. prescriptions per year, Constipation meds (1900–2026). PEG 3350 enters in 1999 (estimated).
FDA-approved for
- constipation (1999)
Principal riskLittle; electrolyte shifts with prolonged use
Classes and tags
Clinical profile
Defining liabilityDiarrhea, bloating and abdominal cramping
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Occasional constipation (BM generally in 1–3 days) | Adults & children ≥17 yr | 17 g (1 capful) in 4–8 oz beverage QD | 17 g QD; ≤7 days | |
| Occasional constipation | Children ≤16 yr | Ask a doctor | Undefined |
Renal Undefined
Hepatic Undefined
Instructions
- Fill cap to top of white section (17 g)
- Stir and fully dissolve in 4–8 oz of any beverage (cold, hot or room temp); do not drink if clumps remain
- Do not combine with starch-based thickeners (dysphagia)
Available strengths
- powder 17 g/dose
Contraindications
- Kidney disease, except under a doctor's advice and supervision
Cautions
- Ask a doctor first: nausea, vomiting or abdominal pain
- Ask a doctor first: sudden change in bowel habits lasting >2 weeks
- Ask a doctor first: irritable bowel syndrome
- Ask a doctor or pharmacist first if taking a prescription drug
- Stop use: rectal bleeding, or worsening nausea, bloating, cramping or abdominal pain
- Stop use: diarrhea
- Stop use: need for a laxative >1 week
Adverse reactions
- Loose, watery, more frequent stools
Pregnancy If pregnant or breast-feeding, ask a health professional before use.
Lactation If pregnant or breast-feeding, ask a health professional before use.
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 17 g/dose | powder | per unit | not offered |
Available combined with: PEG 3350/ electrolytes (GOLYTELY)
Open PEG 3350 in the interactive console ↗
Memory aids: interaction avatars
Open PEG 3350 in the interactive console ↗
Self-check
- PEG 3350: Why does it cause less gas than lactulose?
No bacterial fermentation. - PEG 3350: What is the onset range?
One to three days.