Mewing before and after: what the evidence actually shows

Mewing is the practice of resting your whole tongue flat against the roof of your mouth, often with steady pressure, in the hope of reshaping your face over time. Search for it and you will find hundreds of before and after photos showing sharper jawlines. The short answer: in adults, no controlled study shows that mewing changes the bones of the face, and orthodontists’ professional body says there is no evidence for it. Most before and after photos show changes in posture, camera, light, body fat or growth. This guide goes through what mewing claims, what the research says, what the photos usually capture and what can realistically change, and when.

What mewing claims

The technique is named after John Mew, a British orthodontist whose approach, which he called orthotropics, has long been disputed by mainstream orthodontics. It was popularised online through videos by his son Mike Mew. The instructions vary, but usually include:

• the whole tongue, including the back third, pressed flat against the palate;
• lips sealed, teeth lightly together or just apart;
• breathing through the nose;
• holding this all day, sometimes with extra force (“hard mewing”).

The claimed results are a wider upper jaw and midface, higher cheekbones, a more forward chin, a sharper jawline, a straighter nose and better breathing, over months to years. Some videos claim changes in adults that would normally take jaw surgery.

Where the idea comes from

The idea starts from something orthodontists do take seriously. In growing children, long-term mouth breathing, for example because of enlarged adenoids, has been associated in a number of studies with a longer lower face and a narrower upper jaw. How strong that effect is, and how much of it reverses, is still debated. Mewing takes this childhood link and applies it in reverse to teenagers and adults: if poor tongue posture can shape a growing face, good posture should reshape a grown one. The problem is the word “grown”. The growth sites that respond in a child have mostly finished their work by adulthood, which is what the rest of this section is about.

What the research actually shows

No trials of mewing itself

There are no randomised trials, cohort studies or standardised imaging studies of mewing in adults. In 2019, oral and maxillofacial surgeons writing in the Journal of Oral and Maxillofacial Surgery described mewing as a social-media alternative to jaw surgery that patients were starting to ask about, and pointed out that it was not supported by published evidence. In January 2024 the American Association of Orthodontists warned against the trend. Its president put it plainly: “There’s no scientific evidence to support its claims of reshaping the jawline, and the potential risks outweigh any unproven benefits.”

The nearest research is thin too

The closest studied relative of mewing is orofacial myofunctional therapy: supervised exercises for the tongue, lips and face, usually alongside orthodontic treatment. A systematic review searched eight databases for studies published between 1965 and 2011 and found 355 papers. Only 4 met the criteria, and all 4 had a high risk of bias. The authors concluded there was little consistent evidence that the therapy improves orthodontic correction, even when a professional runs it.

Why adult bone is unlikely to move

The upper jaw widens at a suture that runs down the middle of the palate. In children it is open and responds to force, which is why expanders work well at that age. From the teenage years the suture matures and gradually fuses. A study that staged the suture on 3D scans of 140 people aged 6 to 58 found fusion in girls from age 11 and in some teenage boys, and a microscopic study of people aged 15 to 35 found the degree of fusion varied widely between individuals. Orthodontists check this before trying to widen the palate of a teenager or young adult, because in adults a tooth-borne expander, which pushes far harder than a resting tongue, often fails. Adult palate widening usually needs screws anchored in the bone or surgery.

Teeth move more easily than bone

Orthodontic research has long held that the light pressures that last for hours, from the tongue, lips and cheeks at rest, have more say over where teeth sit than brief heavy forces like chewing. That is the mechanism behind the main risk of hard mewing: sustained tongue pressure is more likely to push teeth than to reshape a jaw. The orthodontists’ warning lists loosened teeth, a changed bite, tooth wear and speech changes.

What before and after photos usually show

A jawline in a photo is bone plus muscle, fat, skin and the angle you hold it at. Almost every one of those can change between two photos without the bone changing at all:

1. Posture. Pushing the chin slightly forward and up stretches the skin under the jaw. Tucking the chin bunches it. Pressing the tongue up also tightens the muscles under the chin, so the area looks firmer while you do it. This is the biggest single difference in most pairs.
2. Camera distance. A phone held at arm’s length enlarges whatever is closest to it. A modelling study estimated that at about 30 cm the nose looks around 30% wider than at 1.5 m, and the face edges and jaw recede. A close “before” and a distant “after” look like different faces.
3. Camera height. A camera below the chin shows the underside of the jaw and neck; a camera above eye level hides it.
4. Light. Light from above or the side draws a shadow under the jawline. Flat front light, like a bathroom mirror, removes it.
5. Body fat. Fat in the face is one of the strongest visual cues people read; studies find perceived facial fat predicts how healthy and attractive a face looks. Losing a few kilograms sharpens a jawline more than any tongue exercise.
6. Growth. Many before and after pairs are of teenagers a year or more apart. The jaw and nose keep growing into the late teens, often a little longer in boys.
7. Lip position. Lips resting apart lengthen the lower face; closing them shortens it. The facial thirds guide shows how the lower third is measured and what changes it.
8. Grooming and selection. A shorter haircut, a beard line, clenching the jaw, and choosing the best of fifty photos all add up.

Questions to ask of any before and after

Before you believe a pair of photos, yours or someone else’s, check:

• Is the camera the same distance away, at the same height, in both?
• Is the light coming from the same direction?
• Is the head held at the same angle, with the chin in the same place?
• Is the “after” taken mid-press, with the tongue pushed up and the jaw clenched?
• How old was the person in each photo, and did their weight change in between?
• Is it one pair out of many, chosen because it looked best?

If the answer to any of these is “no” or “unknown”, the pair cannot tell you whether the bone changed. Most viral pairs fail several of them.

A realistic timeline

• Seconds: posture, tongue pressure and jaw clenching. Visible immediately, gone when you relax. This is the “instant mewing” effect.
• The same day: camera distance, height and light. Enough on their own to produce a dramatic pair.
• Days: puffiness from sleep, salt, alcohol and fluid. Faces are often fuller in the morning.
• Weeks to months: body fat. The one change you control that clearly alters a jawline.
• Years, for teenagers: growth. Real, but it would have happened anyway.
• Adult bone from tongue posture: no evidence of a change on any timescale.

What is fine to keep doing

A relaxed resting posture with your lips closed, your tongue resting lightly against the roof of your mouth and breathing through your nose is how most clinicians describe a normal resting position. If that is all mewing means for you, it is harmless. The problem is force: pressing hard for hours is where the risks to teeth and the jaw joint come from. Stop if you notice jaw pain, clicking, headaches, sore teeth or a bite that feels different.

If you cannot breathe comfortably through your nose, or you snore, that is worth a doctor’s visit in its own right. If you are unhappy with your bite or jaw position, an orthodontist can tell you what is possible and at what age.

How to take an honest before and after

If you want to track any change, yours or anyone’s, hold everything constant except time:

1. Same camera, same distance (1.5 m or more, zoomed in), same height (eye level).
2. Same light: face a window at the same time of day.
3. Same head position: look straight ahead, chin level, neck relaxed.
4. Same face: relaxed jaw, tongue resting, not pressing; no clench.
5. Note your weight and the date. Without the weight, a jawline change means little.

Or measure instead of comparing photos. The side profile analysis reads your jaw angle, chin and nose projection from the turned angles of the scan, so it is not fooled by a flattering pose in the same way a photo is, and it leaves out any measure it cannot read confidently, for example when you barely turned. Scan twice in the same setup to learn how much your numbers vary, then repeat in a few months. The jawline and gonial angle guide explains what those numbers mean and their typical ranges, and the face symmetry test tracks left–right balance the same way. The full report ($14.99) shows your profile from both sides with the spread of every measurement.