Do facial fillers stretch and sag the skin over time?

Thank you for your question! Proper technique and product amount will ensure that your skin does not become saggy over time. The collagen production stimulated by some fillers will continue to reverse the signs of aging. 

Thank you for your question. 
The idea of facial dermal fillers is to replace lost volume in the face, by creating a natural enhancement there should be no stretching of the skin. Dermal fillers can stimulate collagen production so should help reduce skin laxity. 
I hope this helps.

Thank you for your question.  Dermal filler injections to the cheeks and jaw do not cause saggy skin over time but rather promote the production of collagen.  Aging, environmental factors and genetics are a few factors that cause skin laxity.  Best of luck.