Like most syringes on the market, Mosie syringes are single-use. Mosie, like any syringe, is comprised of moving parts that may become compromised after even a single-use. There is also a risk of infection if not cleaned properly. The rubber stopper specifically (on any syringe) loosens after each use and will eventually become unreliable. The stopper on Mosie (and most syringes) is also very lightly coated with a medically safe lubricant to ensure smooth movement which will likely deteriorate after washing.
You will find that Mosie is not alone here. Most manufacturers discourage using a syringe multiple times. This is exactly why we include two Mosie syringes in every kit. More tries translates into better odds for conception!
While you are free to attempt to use Mosie syringes more than once at your own risk, we do not recommend it for these reasons.