Polyethylene Glycol 3350 (PEG 3350): Practical Guide
Polyethylene glycol 3350, often called PEG 3350 or sold as MiraLAX, is an osmotic laxative that helps relieve occasional constipation. It pulls water into the stool, which softens stools and makes bowel movements easier. It’s common, effective, and available over the counter in many countries.
How to use PEG 3350
Most adults take 17 grams (about one heaping tablespoon) dissolved in 4–8 ounces of water once daily. Stir until the powder is fully dissolved. You can take it with juice if you prefer. For children, follow a doctor’s instructions—doses vary by age and weight. Effects typically start within 12 to 72 hours, so don’t expect an immediate bowel movement like stimulant laxatives produce.
Use it short-term for occasional constipation or as directed for bowel prep by your healthcare provider. Don’t keep increasing the dose if it doesn’t work right away. If constipation persists for more than a week or you notice severe pain, bleeding, or unexpected symptoms, stop and contact your doctor.
Side effects and precautions
Common side effects are mild: bloating, gas, nausea, or loose stools. Diarrhea can happen if you take too much. Serious reactions are rare but include signs of allergy or severe abdominal pain. People with a bowel obstruction, severe inflammatory bowel disease, or perforation risk should avoid PEG 3350.
Electrolyte imbalance is uncommon with short-term use, but prolonged or very high doses can affect sodium and potassium. If you have kidney disease, heart failure, or are on fluid-restricted diets, check with your clinician before using PEG 3350. It usually doesn’t interact with many medications, but separate it from other oral meds by at least a couple of hours if possible to avoid absorption changes.
Pregnancy and breastfeeding: many clinicians consider PEG 3350 safer than stimulant laxatives for short-term use in pregnancy, but always ask your obstetrician. For breastfeeding, small amounts passing into milk are unlikely to cause problems, but check with your provider if unsure.
Practical tips: mix the powder fully and drink more water during use. Avoid combining with other laxatives unless a doctor advises it. Store the powder in a cool, dry place and keep it sealed. If you’re prepping for a colonoscopy, follow the exact instructions your clinic gives—dosing and timing can differ from everyday constipation use.
If you’re uncertain about the right dose, worried about side effects, or constipation keeps coming back, talk with a pharmacist or doctor. PEG 3350 is simple and effective for many people, but the right plan depends on your health and medications.
