I have itching & water blisters along the edges of the Tegaderm applied after surgery. How can I prevent/treat blisters? (Photo)

I don't agree at all with such kind of draping, firstly because creates an environment of humidity with the leakage from wounds, prone to infections, secondly because the tight fixation in combination with the normal postoperative swelling may produce shearing forces that will peel of your skin.You don't have any allergic or other kind of intolerance to that draping, it is just a matter of common sense.Take that off and do return to the traditional methods of managing a wound that never pass.

This is typically not an allergic reaction, but one due to swelling. The tape doesnt allow your skin to stretch on the top layer and the swelling makes everything stretch, which is why it is so noticeable at the edges. The tapes should probably be removed, and general care of the blisters is good how your are doing it. Cutting it just makes a new edge for the skin to shear at.

It looks like you are having a reaction to the tegaderm and it would be best to remove them.  Speak to your PS about this as you don't want to have open areas of skin where an infection may happen.