Movicol typically takes about 12 to 72 hours (1 to 3 days) to start working, with most people experiencing a bowel movement within one to two days after taking the first dose. The exact timing can vary depending on the individual, the severity of constipation, and whether it is used for occasional or chronic relief. Movicol is an osmotic laxative that works by drawing water into the bowel to soften stools and make them easier to pass, with effects usually seen within this timeframe.