Thin lips and lost lip definition
Two different problems with two different answers: not enough volume, or enough volume that simply is not showing. A lip flip addresses the second without adding any filler.
Two quite different complaints get described the same way. The first is genuine volume deficiency: lips that are naturally small, or that have thinned with age as fat and collagen diminish and the surrounding skin loses support. The second is a lip with adequate volume that simply is not visible, because the upper lip rolls inward or a strong muscle around the mouth holds it down over the teeth. These need different treatments, and treating the second as though it were the first is why some lip results look heavy. Volume deficiency is addressed with hyaluronic acid filler. A lip that is present but not showing is often better served by a lip flip: a very small amount of botulinum toxin placed in the orbicularis oris along the upper lip, relaxing it so the lip rolls slightly outward and reveals more of the vermilion already there. No volume is added at all. Ageing brings a third element, where the distance between nose and lip lengthens, the philtral columns flatten and the border loses its crispness, and definition rather than volume is what has gone.
How we treat it
The consultation establishes which of the two problems is present, and often it is both. Where volume is genuinely deficient, hyaluronic acid filler is placed conservatively, with attention to the ratio between upper and lower lip and to the shape of the vermilion border rather than to size alone. It is normal to build over two sessions rather than achieve everything in one, because the tissue settles and swelling makes same-day assessment unreliable. Where the lip is present but not showing, a lip flip achieves the effect with a few units of toxin and no filler at all, though it is subtle and lasts only two to three months. Where definition is the issue, precise placement along the border and philtral columns restores structure without adding bulk. Many patients do best with a combination: a flip to reveal the upper lip, and a small amount of filler to balance proportion. Restraint is the whole of the technique here.
Medically reviewed by Dr. Sherwin Hariri, MD, Medical Director & Chief Longevity Physician. Last reviewed August 2026.
This page is for information only and is not medical advice. Suitability for any treatment is determined at consultation.
Common questions
What is the difference between a lip flip and lip filler?
A lip flip uses a few units of botulinum toxin to relax the muscle above the upper lip so it rolls outward and shows more of the lip you already have. Filler adds volume. The flip is subtle and lasts two to three months; filler is more substantial and lasts six to twelve. They address different problems and are often combined.
Will my lips look obviously done?
Not if the volume is modest and matched to your proportions. Overfilled lips come from too much product, or from adding volume when the real problem was a lip that was not showing. Building over two sessions rather than one, and assessing after swelling settles, is how a natural result is achieved.
How much swelling should I expect?
Lips swell more than any other area. Expect significant swelling for two to three days, with most settling within a week and the final result at around two weeks. Bruising is common. Treatment should not be scheduled within two weeks of an event you care about.
How long does lip filler last?
Typically six to twelve months, at the shorter end of the range for fillers because the lips are constantly in motion and metabolise product faster. A lip flip is much shorter at two to three months, because it depends on the toxin rather than on a gel that persists in the tissue.
Other concerns
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