Creatine can be taken in conjunction with other supplements, provided you have consulted with your physician. Take protein powder as an example. The best time to consume both protein supplements and creatine powders is after or before a workout so this means mixing them is an ideal option. However, some forms of creatine should not be mixed. For example, mixing creatine HCL and caffeine should be avoided. You should also keep in mind that caffeine is present in many pre-workout supplements.