Chemotherapy-induced constipation is very common, and it is completely understandable to feel frustrated. Lactulose (Duphalac) can sometimes take 24 to 48 hours to take full effect, so it may still help. Please ensure you are drinking plenty of fluids, as this helps the medication work. If you still have no relief, please contact your oncology team. They may safely recommend adding a generic stimulant laxative, like senna, or a stool softener, like docusate sodium. Please do not start new medications or use suppositories without checking with them first, as your blood counts must be considered.