Yes. Both creatine monohydrate and electrolytes like sodium, potassium, and magnesium have been studied in athletes and healthy adults for months even years, with no harmful effects when used at recommended doses.
Creatine is one of the most researched sports supplements ever, and long-term use has been shown to be safe for healthy kidneys, liver, and brain.
As always, if you have a medical condition, talk to your healthcare provider before starting any supplement routine.