Oh, interesting. I once lost hearing in one ear due to wax blockage and finally got annoyed enough I went to an urgent care clinic. They used a wax softener and then a big syringe with warm water (and maybe something else mixed in) to irrigate my ear canal. That did the trick and cleared it out. I wonder what about using a syringe can be harmful?

> 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.

That NICE guideline says not to use a syringe as it can be harmful. The other commenter used quotes so maybe it was a loose reference to the irrigation devices that they do recommend.