Does Chewing Gum or "Mewing" Actually Build Jawline Collagen?

Written by the Nuvirox Research Team

Short answer: no, not in the way the trend claims. Chewing exercises and "mewing" (a specific tongue-posture technique) are frequently marketed as ways to sharpen your jawline by "building collagen" or reshaping bone. The actual research points somewhere much narrower: repeated jaw-muscle exercise can measurably thicken the masseter muscle, but that’s a muscle effect, not a skin-collagen or bone-remodeling effect, and it doesn’t change the shape of your jaw.

What is "mewing," and what does it actually claim to do?

Mewing is a tongue-posture technique — resting the tongue against the roof of the mouth instead of the floor — that proponents claim can reshape the jaw and midface over time, particularly if practiced from a young age. The theory borrows loosely from orthodontic research on how tongue posture and mouth-breathing can influence jaw development during childhood growth, when facial bones are still actively forming. The trend then extrapolates that same logic to adults, whose facial bones have finished growing, and adds claims about firming skin and "building collagen" along the jawline — a mechanism that mixes up bone remodeling, muscle tone, and dermal collagen as if they were interchangeable.

What does the actual gum-chewing and jaw-exercise research show?

The most direct recent test measured muscle and bone shape, not skin. Jung MH, et al. Effects of gum chewing training on occlusal force, masseter muscle thickness and mandibular shape: a randomised controlled clinical trial. J Oral Rehabil. 2024. DOI: 10.1111/joor.13830. [RCT: gum-chewing training increased masseter muscle thickness and bite force but produced no change in mandibular (jawline) shape.] This is a genuinely useful trial because it directly tested the specific claim people make about jaw exercises — that repeated chewing changes facial shape — using objective 3D imaging of the mandible rather than self-reported appearance. The muscle got stronger and thicker. The bone did not change shape.

Older, smaller studies found similar muscle-only effects. Earlier research on chewing exercises in older adults found that regular chewing training increases masseter muscle thickness and bite force, which is a legitimate functional benefit for people with age-related declines in chewing strength. None of these studies measured or reported changes to skin collagen density or facial bone structure, because that was never the plausible mechanism at work.

Even the muscle effect has a caution attached. Overdeveloping the masseter through aggressive gum-chewing or jaw-exerciser devices can, in some cases, make the lower face appear wider rather than sharper — the opposite of the "chiseled jawline" result people are usually chasing. Excessive clenching-type exercises have also been associated with jaw joint (TMJ) irritation in case reports, which is worth knowing before committing to a heavy daily routine.

What actually affects jawline definition and skin firmness

Jawline appearance is a combination of bone structure (fixed after growth plates close), subcutaneous fat distribution, muscle tone (masseter and platysma), and the overlying skin’s elasticity and thickness — four different tissue types, none of which mewing has been shown to meaningfully change in adults. For people specifically concerned with skin laxity along the jaw and lower face rather than muscle or bone, our piece on collagen and a sagging jawline or double chin looks at the skin-specific side of that concern. For a comparison of non-invasive versus injectable approaches to jawline and lower-face definition, see collagen supplements versus Botox.

Are there any real downsides to trying it?

Gentle jaw exercise itself is low-risk for most people. The main things worth watching for: jaw pain, clicking, or popping that develops or worsens with a new routine (a sign to stop and see a dentist or TMJ specialist), and unrealistic expectations that lead people to abandon things that actually do have evidence behind skin quality — sun protection, retinoids, and the general collagen-supplementation research base — in favor of a technique whose central claim isn’t supported.

Why this trend spread so widely despite the thin evidence

Part of what makes mewing compelling is that the before-and-after photos circulating online are genuinely striking in some cases — but photo comparisons are one of the weakest forms of evidence in aesthetics generally, since posture, camera angle, lighting, incidental weight change, and simple photo selection (posting the flattering angle, not the average one) can all produce a convincing-looking "transformation" without any underlying tissue change at all. This is a broader pattern worth being alert to across aesthetic and wellness trends, not specific to mewing: a compelling before-and-after pair is not the same evidentiary standard as a controlled trial with blinded 3D imaging, which is exactly the kind of measurement the 2024 gum-chewing trial used and which is why its null finding on jawline shape carries real weight despite being less viral than a dramatic transformation photo. If you're evaluating any jawline or skin-firming claim online, asking whether it was measured with an objective tool or just photographed is a genuinely useful filter.

Frequently asked questions

Can mewing work if I start as a teenager while my jaw is still growing?
The orthodontic literature on tongue posture and jaw development during active growth is a different, more established body of research than adult mewing claims. That’s outside the scope of this article, which focuses on adult, post-growth claims about collagen and jawline reshaping.

Do jaw-exerciser devices (chewing balls, resistance gums) work better than regular gum?
The trial referenced here used standard chewing gum training. Weighted jaw-exerciser devices haven’t been shown in controlled trials to produce a fundamentally different outcome, and some case reviews note a higher risk of masseter overdevelopment or jaw irritation with heavier resistance devices.

If chewing thickens my masseter, will that make my jawline look more defined?
Possibly, for some face shapes, since a thicker masseter can add some lower-face structure. But it’s a muscle-bulk effect, not the bone-reshaping or skin-tightening effect the mewing trend describes, and it can also widen the lower face in a way some people don’t want.

Is there any evidence mewing improves skin collagen along the jaw?
No controlled study we could locate measured skin collagen density as an outcome of tongue-posture or jaw-exercise practice. The claim appears to be an extrapolation, not a tested finding.

The bottom line

The kernel of truth in the mewing trend is real: repeated jaw exercise can measurably thicken your chewing muscles. Everything built on top of that — that it reshapes adult jaw bone or "builds collagen" — runs ahead of what the actual trials measured, and the one study that tested the shape-change claim directly found no effect. If jawline skin quality specifically is your goal, that’s a different question with a different, better-supported evidence base than mewing itself.

References

1. Jung MH, et al. Effects of gum chewing training on occlusal force, masseter muscle thickness and mandibular shape: a randomised controlled clinical trial. J Oral Rehabil. 2024. DOI: 10.1111/joor.13830. [RCT: gum-chewing training increased masseter muscle thickness and bite force but produced no change in mandibular (jawline) shape.]
2. de Miranda RB, Weimer P, Rossi RC. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. Int J Dermatol. 2021;60(12):1449-1461. DOI: 10.1111/ijd.15518. PMID: 33742704.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.