MiraLAX is a safe, effective way to treat constipation.* Now available without a prescription, MiraLAX is a tasteless, grit-free powder that is mixed with water—or any other everyday beverage—and taken once each day. MiraLAX relieves constipation by gently bringing water into the bowel. This provides softer stools and increases the frequency of bowel movements, allowing bowel movements to occur more normally.