Ex-lax is a stimulant laxative containing senna, which comes from plant leaves. Ex-lax is called a stimulant laxative because the senna stimulates the muscles of the bowel wall to increase contractions, and therefore move food faster through the colon. Ex-lax treats short-term symptoms of constipation. As with other stimulant laxatives Ex-lax may produce side effects such as cramping or 'griping' pains in the stomach. Ex-lax may also produce an urgent need for a bowel movement. Ex-lax is available in various forms and strengths. The tablet form is available in regular and maximum strength, and there is also a chocolate version. As with all laxatives, Ex-lax is not suitable for long-term use.