For every reputable expert using Instagram to promote their business, there is a charlatan doing the same. They may win you over with impressive pictures and positive reviews but the dangers can't be ignored.
In the UK, you do not need to be a legitimate, qualified expert to administer filler or Botox, nor do you have to prove your qualifications to advertise an aesthetics business on Instagram.
I had under-eye filler. Some months later, my eyes started to swell and form huge sacs of fluid which caused extreme pain and discomfort.