Under eye hallows / loose skin under neck. How can I fix this?

Often the under eye hollows can be improved with surgery and/or fat grafting. Loose skin on your neck usually requires a lower facelift to improve. Best to see an expert for an in person consultation.

Thank you for your question. In general, reversal of the buccal fat reduction is carried out using fat transfer.
Because you were significantly surprised by the effect of the treatment you already had, there is potential value to a temporary reversal treatment in in the first instance, incase you dislike the outcome.
This could be carried out with fillers or with Sculptra.

In terms of the characteristics of the neck, it sounds like a neck lift intervention would be the appropriate intervention.

Unfortunately, no photos were provided. So, I can only answer in general terms.
HA fillers have been used for many years to treat tear troughs and under-eye hollows. For some people a robust HA volumizing filler injected properly and the appropriate location on the upper cheeks can help to significantly, secondarily improve the under-eye area without the need for direct injection in that location. For others, the direct injection in the appropriate locations of a low viscosity, malleable, cohesive HA filler is the required approach.
It is very difficult without photos to comment on the neck, except to say that I have been using HA fillers of various kinds to address all kinds of neck issues (alone or in combination with Botox), from laxity, to horizontal "necklace" lines and vertical neck cords.
Thees kinds of treatments should be left to the hands of experienced injectors and not novice, cut-rate venues selling treatments by the syringe and accustomed only to treating simple smile lines with ordinary Restylane or plain Juvederm.
You would be wise to consult with an experienced, board certified cosmetic dermatologist filler expert. Hope this helps.

Facial aesthetics are primarily determined by bone structure.
It is facial skeletal structure that gives each unique person there individual appearance whether it is aesthetically desirable or not so much pain certain types of facial skeletal structure are predisposed to developing undesirable soft tissue characteristics.
For example, individuals who have a small mandible or one that lacks forward projection will often develop loss of jawline definition, premature double chin and premature jowls, etc.
Sometimes soft manipulation can be helpful.
I’m not a big fan of buccal fat reduction.
It tends to cause premature facial aging.
Without pictures, we can’t begin to make an assessment.
If you’ve had surgical intervention, then you should include before and after pictures.
There is no shortage of treatment options to improve facial aesthetics.
There is a multi billion dollar industry supporting peoples desire to look better.
Consider checking out the website of Dr. David Mabrie MD in San Francisco.This website doesn’t allow us to include links so you’ll have to look it up.
His practice is based exclusively on treatment with facial fillers.
His work is some of the best I’ve ever seen.
I’m not suggesting everybody fly to San Francisco to get facial fillers done, but seeing his work can give an understanding of what is possible Without surgical intervention in the hands of the right provider.
Best,
Mats Hagstrom MD