They are Syn free as they use saccharine or aspartame.
(First: hygiene and health. The chemical make-up of your vagina is naturally acidic, composed of bacteria, which helps to monitor its chemical balance and keep you clean and healthy. Sugar alters this balance, changing bacterial makeup and raising levels of yeast. This means that flavored condoms can result in yeast, bacterial and even bladder infections. (Believe me โ Iโve been there.)
Second: additives and chemicals. If you look at the actual ingredients of flavored condoms, sugar is not among them. Instead, the condoms are coated with glycerine, sodium saccharine or aspartame.) Source:
http://www.empowher.com/sexual-well-being/content/flavored-condom-myths-facts