My GP says it is the safest pain med to use.
Like any drug, overdosing can cause problems.

Found this in Pharmweb, and is typical of other entries that I found.

Q:If paracetamol products are used long term, is there a risk of liver damage?
A :Many people use paracetamol for extended periods under supervision of their GP. There is no evidence to show that, at recommended dosages, paracetamol causes liver injury when used for long periods (4).