Duphalac Oral Solution Lemon is used in the treatment of Constipation,Intestine preparation before any surgery,Hepatic encephalopathy. Discover why Duphalac ® has been trusted by generations for gentle and effective relief from constipation. Duphalac oral solution is used in the treatment of constipation. It works by increasing the water content of the stools and increasing bowel movements to make the passage of stools easier.