I am currently weight training with cardio. I currently use ephedrine but have recently purchased creatine. It is OK to use both this substances at once?

Creatine is fine, particularly before and after exercise. There's a lot of research to show that it improves endurance and strength without dangerous side effects.

The ephedrine, on the other hand, is strictly for use under doctor's supervision. I would drop this and keep the creatine.