> what about using a syringe can be harmful?

Pushing it too far in, using water that is too hot, pushing the water in too fast. All can damage your ears.

I have had my ears syringed twice. In both cases at my doctor's surgery by a nurse. I visited my doctor because I started to notice that I was going deaf in one ear and ear drops didn't seem to work. Syringing worked perfectly and removed a surprising large amount of wax.