Flex Pharma, Inc. is a biotechnology company. The Company develops treatments for nocturnal leg cramps, muscle cramps and spasms associated with severe neuromuscular conditions, and exercise associated muscle cramps (EAMCs). The Company's product candidates activate certain receptors in primary sensory neurons, which then act through neuronal circuits to reduce the repetitive firing, or hyperexcitability, of alpha-motor neurons in the spinal cord, thereby preventing or reducing the frequency and intensity of muscle cramps and spasms. The Company operates through developing and commercializing products for nocturnal leg cramps, muscle cramps, spasms and spasticity associated with severe neuromuscular conditions, and exercise-associated muscle cramps segment. The Company's lead drug product candidate is FLX-787, which is in the Phase II clinical trial stage. It is developing a consumer brand and products specifically formulated to treat athletes suffering from EAMCs.