Pure Canna CBD For the full benefits of CBD, use the product for at least thirty days. Pure Canna CBD Side Effects It’s extremely rare for us to hear about anyone who notices side effects when using creams like this. In very isolated circumstances, they can occur, so here’s what you need to know about them. If you notice any health problem occurring when you begin using Pure Canna CBD cream, stop usage right away. Consult with a doctor to address and medical issue that may have caused the problem.