Are there any side effects from 35% carbamide peroxide to whiten your teeth?

Bleaching teeth. There are always side effects to anything not naturally produced by our bodies. The most common side effect is teeth sensitivity and sloughing of the gums. Both usually a result of over bleaching.
Sensitivity+Recessio. High dose carbamide peroxide can lead to increased sensitivity of teeth, sometimes severe. It can also be associated with recession of the gums & exposure of the tooth roots & any crown margins. While this can happen with any whitening therapy, dentists pay particular attention to the details of using this level in isolating the teeth when used with in-office bleaching or custom tray fabrication.
No, but... This is the highest concentration of carbamide peroxide available for home whitening, and is very effective if your dentist determines that you are a good candidate for this type of whitening product. You must follow the instructions given by your dentist to avoid teeth sensitivity and gum irritation. But, if used correctly, it's safe and very effective.