- Carisoprodol is a muscle relaxer that blocks pain sensations between the nerves and the brain.Carisoprodol is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.Carisoprodol should only be used for short periods (up to two or three weeks) because there is no evidence of its effectiveness in long term use and most skeletal muscle injuries are generally of short duration. Carisoprodol is considered a controlled substance in the United States.