MiraLAX (polyethylene glycol 3350) generally takes about 1 to 3 days to produce a bowel movement when used for occasional constipation. This is because it works by drawing water into the colon to soften stool and increase stool volume, rather than stimulating the intestines directly

. Some sources note that MiraLAX can start to work within 12 to 24 hours for some individuals, but it may take longer-up to 96 hours (4 days)-especially if constipation is severe or caused by underlying conditions

. Unlike stimulant laxatives, MiraLAX does not usually cause a sudden urge to have a bowel movement and provides a gentler, gradual relief. Factors influencing how fast MiraLAX works include:

• Dosage taken (standard dose is 17 grams dissolved in 4-8 ounces of liquid)
• Severity and cause of constipation
• Individual digestion speed and existing gastrointestinal conditions
• Staying well hydrated to help the medication work effectively

For bowel preparation before a colonoscopy, a larger dose of MiraLAX combined with other laxatives can induce bowel movements within a few hours, but this is a different usage than for occasional constipation

. In summary, expect MiraLAX to work within 1 to 3 days, with some variation depending on individual factors. If no bowel movement occurs after 7 days of use, or constipation worsens, consult a healthcare provider