Jaw Exercisers: Do They Work for Your Jawline?

Last verified November 2, 2026. Every grade and study figure on this page links to the source we checked. Where we couldn't confirm something, we say so.

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The short answer

Jaw exercisers are silicone or rubber pieces you bite down on, again and again, to "train" the chewing muscles. They are sold as a way to get a sharper, wider jawline. There is no good evidence that they do that. The best trial of chewing training we found ran for 6 months and found no change in the size of the chewing muscle or the shape of the jaw.¹ Orthodontists say there is no scientific evidence that chewing changes the shape of your face,² and dentists have warned that hard-resistance trainers put extra stress on the jaw joint.³ If you have jaw pain, clicking or locking, skip them and see a dentist. If you want a different jawline, ask an orthodontist or oral surgeon what is realistic.

What jaw exercisers are

Most products fall into three groups:

• Resistance trainers. A rubber or silicone piece that sits between the front or back teeth, sold in graded resistances. Jawzrsize, the best-known brand, used 20, 25 and 40 lb devices in its own study.⁴
• Chew tabs and "jawline balls". Small silicone pieces you chew through the day, usually sold in packs with two or three hardness levels.
• Hard gums. Firmer-than-usual chewing gums, including mastic resin. We cover mastic in our mastic gum guide.

The pitch is the same for all of them: chewing works the masseter, the muscle at the angle of the jaw; a bigger masseter makes the lower face look wider and more defined. The first half of that is true. The second half has not been shown.

What the evidence says

A = consistent meta-analyses of randomized trials. B = a meta-analysis or several good trials with a moderate effect, in a narrower group. C = small effects, or small or few trials. D = too little evidence. X = tested, and the claimed effect did not show up.

Claim	Grade	What the best evidence found	Caveat
A sharper or wider jawline from a jaw exerciser	D	We found no published controlled trial of a consumer jaw exerciser that measured jaw shape. The British Orthodontic Society says there is no scientific evidence that chewing changes the shape of your face.2	Absence of trials, not proof of no effect
Bigger chewing muscles or a reshaped jaw from chewing training	X	A randomized trial of 58 healthy adults: chewing gum three times a day for 6 months did not change masseter thickness or jaw shape compared with no training.1	Ordinary gum, not a resistance device
A stronger bite	C	In the same trial, bite force rose by 3 months, apparently because more of the teeth were in contact.1 An earlier study of a silicone bite device also found higher bite force, but the gain faded after training stopped (as reported by Medical News Today).5	Bite force is not a look
Less double chin or facial fat	D	We found no trial. Medical News Today's dentist-reviewed article found "not much scientific evidence" for toning the face or reducing facial fat.5
Fewer wrinkles	D	The only data is a 30-day company study with no control group, inconsistent participant numbers (20 or 30) and no published paper.4	Company-run, unpublished
Relief of jaw pain (TMD) from a jaw exerciser	D	No trial of these devices for jaw pain. The UK dentists who wrote to the British Dental Journal challenged this marketing claim.3
Relief of jaw pain (TMD) from gentle, prescribed jaw exercises	B	A 2023 meta-analysis of 16 randomized trials (812 people) found therapeutic jaw exercise reduced pain and improved mouth opening.6	Different exercises from biting on a trainer; certainty not graded in the abstract

The trial that matters most here is the 2024 Yonsei University study.¹ It is the closest test of the jaw-trainer idea: regular, deliberate chewing for half a year, with an untrained control group and measurements of the muscle and jaw. Bite force went up. Muscle thickness and jaw shape did not change. A harder device might do more, but nobody has shown it, and the harder the device, the bigger the load on the joint.

This matches how we grade the same claim elsewhere on MoveWell. Our mastic gum guide grades the jawline claim X for the same reason, and our mewing guide and looksmaxxing guide find no good evidence that tongue posture or jaw training reshapes an adult face.

The TMJ risk

The temporomandibular joint (TMJ) is the hinge in front of each ear. It has a small disc of cartilage between the bones. Problems with the joint and the muscles around it are called temporomandibular disorders, or TMD. Symptoms include pain around the jaw, ear or temple, clicking or grinding, trouble opening the mouth fully, and pain that gets worse when you chew.⁷

In 2021, two UK dentists wrote to the British Dental Journal about Jawzrsize, a rubber trainer used against 20 to 40 lb of resistance. They argued that repeated biting on it "will result in far more stresses on the TMJ", could wear the joint's disc, and could bring on TMD symptoms from joint noise to dislocation. They compared the loading to what people who clench or grind their teeth put through their jaws.³

The NHS advice for people with TMD points the same way: eat soft foods, and do not chew gum or pen tops, bite your nails or clench your teeth.⁷ The Royal College of Surgeons' patient guide says chewing gum can make your jaw tired and your pain worse.⁸ Medical News Today's dentist-reviewed article adds that excessive force may cause problems for people with weaker teeth or existing dental work, and that long periods of chewing or clenching may lead to TMD.⁵

Who should not use a jaw exerciser:

• Anyone with jaw pain, clicking, popping, locking or a history of TMD.
• People who clench or grind their teeth.
• Anyone with braces, aligners, crowns, bridges, implants, veneers or loose or sensitive teeth. Ask your dentist first.
• Children and teens whose jaws are still growing. Ask a dentist or orthodontist instead.

Stop and see a dentist if your jaw starts to hurt, click or feel stiff. Get urgent help if your jaw locks, you can't eat or drink, or you have severe headaches or vision problems along with jaw pain; the NHS lists these as signs of a problem that needs urgent treatment.⁷

Jaw exercises that do have evidence

There is a kind of jaw exercise with decent evidence, but it is for jaw pain, not looks, and it is not the same as biting on a trainer. Physiotherapists and dentists prescribe gentle exercises for TMD: controlled opening and closing, side-to-side movements, and light resistance from your own hand. A 2023 meta-analysis of 16 trials found these reduced pain and improved how far people could open their mouths.⁶ The dentists who criticised resistance trainers suggested this kind of simple hand-resistance exercise as the more conservative option.³

If your jaw hurts, start with a dentist or a physiotherapist who treats jaws. They can tell you which exercises fit your problem and how hard to push.

If you want a more defined jawline

None of these is a quick fix, but each is more realistic than a jaw trainer:

• Overall body fat. Losing body fat may make your jawline more visible. Our looksmaxxing guide covers what changes your face and what doesn't.
• Posture and camera angle. Head position, lighting and lens angle change how a jaw looks in photos, which is why online before-and-after pictures are hard to judge. See forward head posture and how to do a chin tuck.
• Tongue posture and nose breathing. Reasonable habits on their own terms, but not a way to reshape an adult jaw. See tongue posture and mewing.
• A professional opinion. For a real bite or jaw problem, the American Association of Orthodontists says orthodontic treatment is the safest and most effective route.⁹ An oral and maxillofacial surgeon can explain what surgery can and can't do.

If you still want to try one

We don't recommend jaw exercisers, and this page links to none. If you decide to try one anyway, these precautions follow from the risks above. They are not a tested protocol.

• Check with your dentist first if you have any dental work or a history of jaw problems.
• Start with the softest piece, and use it for a few minutes, not hours.
• Don't chew to the point of fatigue or ache, and take rest days.
• Stop at the first sign of clicking, popping, pain, headache or a change in how your teeth meet.
• Don't judge results from mirror selfies. Lighting and angle can change a jaw more than a month of chewing.

Common myths

• "It's just like training any other muscle." Partly. Chewing training can raise bite force.¹ But in the best trial the muscle did not get measurably thicker, and unlike a bicep, this muscle works across a small joint that is easy to overload.³
• "It's clinically proven." Jawzrsize says its device "has been clinically proven", based on a 30-day study of its own devices with no control group and no published paper.⁴
• "It fixes TMJ." No jaw trainer has been tested for this, and the NHS advises people with TMD to avoid chewing gum.⁷

FAQ

Do jaw exercisers work?

They can make your bite stronger. They have not been shown to change the shape of your jaw or face, and a 6-month chewing trial found no change in muscle thickness or jaw shape.¹

Can jaw exercisers cause TMJ problems?

Dentists writing in the British Dental Journal warned that repeated hard biting on a resistance trainer puts far more stress on the jaw joint and could bring on TMD symptoms.³ We found no study that measured how often this happens.

Is chewing gum good for your jawline?

There is no good evidence that it is. The British Orthodontic Society says there is no scientific evidence that chewing changes face shape.² See our mastic gum guide for the hard-gum version of this claim.

How long do jaw exercisers take to work?

There is no timescale, because there is no evidence they change jaw shape at all. Bite force rose by 3 months in the chewing trial.¹

Are jaw exercisers safe for teenagers?

We wouldn't use one. Teens' jaws and bites are still developing. If you're worried about a teen's jaw or bite, ask a dentist or orthodontist.

Is mewing better than a jaw exerciser?

Neither has good evidence for reshaping an adult face. Light tongue contact with the palate is low risk; pressing hard is not.⁹ See our mewing guide.

Related: mewing, looksmaxxing, mastic gum, tongue posture, gua sha.

Featured photo by Anne Nygård on Unsplash.

References

1. Jung HJ, Hwangbo NK, Park Y, Ahn HJ. 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. Source
2. British Orthodontic Society. Claims about orthodontics, 26 January 2024. Source
3. Nagpal T, Gupta A. Letter on the Jawzrsize jaw trainer. Br Dent J, 26 February 2021 (reported by DrBicuspid, 1 March 2021). Source
4. Jawzrsize. Does Jawzrsize work? Results from an independent clinical study (company blog, accessed 2 Nov 2026). Source
5. Johnson J, medically reviewed by Archibald J. Jawzrsize review: does it work? Medical News Today, 30 October 2020. Source
6. Idáñez-Robles AM, Obrero-Gaitán E, Lomas-Vega R et al. Exercise therapy improves pain and mouth opening in temporomandibular disorders: a systematic review with meta-analysis. Clin Rehabil 2023;37(4):443-461. doi:10.1177/02692155221133523. Source
7. NHS. Temporomandibular disorder (TMD). Source
8. Royal College of Surgeons of England, Faculty of Dental Surgery. Jaw problems (TMD): what you need to know (patient guide). Source
9. American Association of Orthodontists. Risks of mewing (news release, 22 January 2024). Source