Methods, devices, and remediation compositions for the microwave remediation of medical wastes are provided. The remediation compositions include a microwave active fluid including a microwave active liquid, a microwave enhancer, and a viscosity modifying agent. Methods include immersing medical waste in the remediation composition and then irradiating the medical waste and the remediation composition to remediate the medical waste. The devices include a container for the medical waste and the remediation composition, a microwave radiation source and a temperature monitoring device.