I doubt that it is the Shea butter that is causing the itchiness in the Cantu Shea butter Leave in.
I suspect that it was Steralkonium chloride. I used a conditioner with this ingredient and it caused major itchiness. I ended up having to shampoo my hair again not long after using it. After this happened I did some research and found that this ingredient can cause skin and eye irritation.
I've used Cantu Shea butter in the past but I never put it on my scalp because the instructions say 'Avoid applying any styling or conditioning product directly on new growth', so I figured that there was something in the product that wouldn't be good for the skin.