A laxative is defined as,

A substance that is used to promote a bowel movement when you are constipated.

Laxatives work by starting and stimulating peristaltic action. Peristaltic action is a wave like movement that occurs throughout your gastrointestinal tract – esophagus, stomach, small intestine, colon – that helps move your food into your stomach, through your intestines, through your colon, and out your rectum.

There are drugstore products, natural occurring foods, special nutrients, liquid preparations, herbal substances, and homeopathic liquids that have laxative effects. I do not recommend using drugstore laxatives or any other form of drugs to clear a constipation problem.