The Little-Known Side Effect Of Masseter Botox I Didn’t Expect

I can pinpoint the exact moment I knew I had to do something about my jaw pain. It was my birthday, and a friend cracked a joke so good that half the drinks on the table toppled as everyone doubled over laughing. I, meanwhile, could barely move my mouth; smiling, talking, even laughing felt like lifting weights with my face.  

That’s why I owe a lot to a beauty editor friend of mine, who told me she’d been in the same boat — and that masseter Botox, injected into the masseter muscle along the lower jaw, had completely changed her life.  

Within hours of talking to her, I’d booked an appointment with the injector she swore by, and a week later, I could eat, speak, and laugh again without my jaw snapping shut. The pain and tension — probably from stress-induced teeth clenching — had vanished, and I finally felt human again. But as I enjoyed my newfound freedom, I noticed a subtle change in my face. It had a slightly more oval shape, and I’m convinced the skin along my jaw felt a little looser than before. My experience isn’t unique — but it does raise some important questions. 

While Botox — a purified neurotoxin — is widely used for smoothing fine lines and wrinkles by relaxing the muscles underneath the skin, more experts are recommending it as a solution for jaw pain, clenching, teeth grinding, tension, and clicking. Conversation around it is booming. On TikTok, the hashtag #masseterbotox has amassed 158 million views and counting, with both experts and patients sharing their experiences. 

Dr. Moustafa Mourad, MD, FACS, a double board-certified facial plastic surgeon and masseter Botox expert, who did not perform my treatment, describes it first and foremost as a treatment with real functional benefits: “An aesthetic effect is a secondary bonus,” says Dr. Mourad. “Masseter Botox can be incredibly helpful for patients who clench or grind their teeth, deal with chronic jaw tension, or feel jaw pain and fatigue by the end of the day,” he adds. “By relaxing an overactive masseter, we’re reducing the force transmitted through the jaw and teeth, which often translates into less pain, less tightness, and fewer tension headaches.” 

But it would be remiss not to acknowledge the aesthetics of it all. Dr. Mourad confirms that masseter Botox can reduce muscle volume. “When it’s done thoughtfully, this can create a more tapered lower face, which is why it’s popular in patients with true masseter hypertrophy,” he says — essentially an enlarged jaw muscle that affects the natural shape of your face. In my case, I had been grinding my teeth for so long that my masseter had become large and strong, giving my jawline a sharper, more rigid appearance.  

A more oval face isn’t the only change I noticed. I’m almost certain that masseter Botox contributed to a very slight shift in skin texture, making it look and feel a little looser — something I picked up on myself, rather than anything anyone else noticed. To the naked eye, the change was very minimal, but I’m not alone in this observation. As searches for masseter Botox increase, more people are also googling whether it can cause “jowls” or sagging skin along the jawline.

Dr. Mourad tells me that “jowling” after masseter Botox is not caused by Botox damaging the skin: “Rather, it is related to changes in facial support over time,” he explains. Loose skin isn’t something Dr. Mourad typically sees after one, two, or even three treatments. “It is more commonly seen in patients who have been receiving masseter Botox chronically over many years,” he tells me, adding that it’s only with sustained relaxation that true muscle shrinkage can potentially change the shape of the lower face. “[In this case], instead of a more defined, angular jaw contour, the lower face may appear softer and rounder,” he says. 

In fact, Dr. Mourad notes that he usually only sees looser skin after masseter Botox in patients who already have existing skin laxity or are experiencing age-related collagen loss — a completely normal part of aging. In other words, the Botox itself is rarely, if ever, the cause.

Unlike filler, which you can dissolve if you don’t like it, Botox can’t be undone. It does wear off eventually, and the muscle goes back to normal, but that can take up to six months. Dr. Mourad says that as the muscle returns, some support can come back, too, which has been the case in my experience. With chronic atrophy, though, it could leave the lower face looking rounder and loose skin more noticeable.  

If you’re concerned, it’s worth seeing a qualified injector who really knows their stuff. Dr. Mourad says that in many cases, the risk of loose skin can be minimized with careful planning and restraint. “I am very deliberate about dosing and treatment frequency,” he says, stressing the importance of not over-weakening the muscle, spacing treatments properly, and reassessing the face over time.

He also evaluates each patient’s facial structure and the quality of their skin on their lower face before recommending long-term masseter Botox treatment. “In some patients, especially those who are aging or already showing early jowling, I will limit the use of masseter Botox or recommend alternative approaches to managing jaw pain that do not contribute to progressive muscle atrophy,” he adds. 

If you’re committed to masseter Botox but have noticed some skin sagging and want to address it, Dr. Mourad suggests considering other treatments, like jawline filler or skin-tightening options such as lasers. 

Dr. Mourad says that most other side effects of masseter Botox are mild and temporary, but it must be performed by a qualified injector. “Patients may experience localized soreness, swelling, or bruising, and some notice temporary difficulty chewing very hard foods as the muscle weakens,” he explains. Less common, but still possible — especially in underqualified hands — is the toxin spreading into nearby muscles, which can lead to temporary asymmetry, like a slightly altered smile, he adds. 

While Dr. Mourad is a big fan of masseter Botox treatment — especially for relieving pain and tension — he emphasizes the importance of using it thoughtfully. “It should be revisited regularly, and not approached as an indefinite routine maintenance treatment,” he concludes. 

I’ll definitely try masseter Botox again. We’re living in a stressful world, and for me, teeth grinding has become part of the deal. Next time, though, I’ll ask for a lighter touch — and work harder at managing my stress. Any subtle changes to my face shape are a trade-off I’ll take over the pain of constant clenching; like most treatments, it’s about weighing up the pros and cons. And yes, I’d still recommend it. It can be truly life-changing.