Unfortunately, all too many inexperienced injectors have created lips, perhaps even at the urging of the patient, that in side view look "duck like" or what has been called the "trout pout" and in front view appear like "sausage" lips. This comes from a lack of awareness of the appropriate and natural proportions of the lips in relation to each other and to the surrounding skin and that any exaggeration of these proportions can give rise to the undesirable results just described. The intent of treatment is not to have a person's lips enter the room before she does. It may be that in this case the upper lip alone can be treated, but such an assessment must be carefully made at the time of consultation taking into account the entire aesthetic unit of the lips and surrounding skin.
For lips to look natural, the upper lip, in side view, should project slightly more than the lower lip, in a ratio of approximately 1.5X more than the outward projection of the lower lip. In front view, the ratio is reversed. In vertical height, the ideal lower lip should be approximately 1.5X that of the upper lip. For the body of the lips, I generally prefer Juvederm UltraPlus XC.
Besides keeping these proportions in mind, treatment with fillers and/or volumizing injectables, must also be directed, when appropriate, to other detractors of the lips if present. These include loss or flattening of the philtrum and Cupid's bow and loss of border definition, "lipstick bleeding" lines (aka "smoker's lines), diminution of the so-called "white roll' that defines the separation between the red lips and the skin above and below the lips. And if the angles of the mouth have become downturned, this, too, must be addressed in order to maximize the benefits of lip rejuvenation. For the philtrum and Cupid's Bow, I have found Restylane L helpful; for smoker's lines, Belotero Balance; for the vermilion border, Juvederm Ultra XC; and for the angles of the mouth Radiesse combined with Perlane L.
From the above, it should go without saying that consultation and treatment by a board certified aesthetic physician with extensive experience in treating the lips is crucial for a gratifying outcome.
Web reference: http://YoungerLookingWithoutSurgery.com