“You know masseter injections can cause jowls, right?” If only I had a dollar for every time I heard that phrase from fellow beauty editors and friends. Turns out, jowls were the least of my worries. I’d had the treatment (in which a neuromodulator like Botox or Daxxify is injected into the masseter muscles near the jaw) to slim my round face. I never knew I could be left with a crooked smile. (BTW, masseter injections don’t actually cause jowls, but more on that later.)
My smile is my favorite feature. I probably spend the majority of my days beaming from ear to ear. When my smile became distorted, I felt like I had lost a part of my identity. It was so disorienting to look in the mirror and not recognize myself. And the thing is, it didn’t just take a toll on my physical appearance; it affected my psyche, too. I stopped smiling. I refused to pose for pictures. I missed out on get-togethers with friends because I couldn’t stand to be around people when my smile was foreign to me.
There was nothing I could do about it until the neuromodulator wore off. Five months later and my smile is finally back to normal. I’m grateful the effects weren’t permanent, but nearly half a year was a long time to deal with the aftermath.
My experience with masseter injections wasn’t always so tumultuous. I’d had them once before and had loved the results. So…what happened this time? Is there anything you can do to prevent your smile from becoming lopsided? I set out to learn everything I could about masseter neuromodulator.
Why have masseter injections become so popular?
"Masseter Botox is sought out for three main reasons: facial slimming, correction of facial asymmetry, and relief from teeth grinding,” says Nicole Lee, MD, a board-certified dermatologist in Garden City, New York. “For those who clench or grind their teeth, neurotoxin relaxes the jaw, which eases tension, prevents enamel damage, and even reduces headaches.” She says it can be “life-changing” for anyone dealing with TMJ, also known as jaw pain.
Dr. Lee says that injecting neuromodulators into the masseter muscles has been popular in Asia for more than a decade, in part because the facial structure of the population is naturally rounder or more square. The treatment really took off in the early 2000s, and studies have shown that Botulinum toxin injections for masseter reduction in East Asians are effective for slimming the masseter muscles without significant side effects.
Following its popularity in Asia, dermatologists have seen an uptick in requests for masseter injections in the US, too. Also, American stress levels have been steadily increasing year over year, and studies show that people who are stressed are more likely to develop bruxism—a.k.a. teeth clenching and grinding. Personally, I was hooked from the first needle because the slimming effect on my full-looking jawline was striking. That’s probably because I have the ideal facial structure and skin—a round face and taut skin—for those results, according to Marnie B. Nussbaum, MD, a board-certified dermatologist in New York City. “The outcome really depends on your facial musculature, skin laxity, and muscles,” she adds.
Those first two factors play a major role in the aforementioned “jowling” that has been going viral on TikTok. “Masseter Botox itself doesn’t cause jowls, but in a certain facial anatomy, it can make them more noticeable,” explains Dr. Lee. “This is especially true for patients with a recessed chin (micrognathia) or significant skin laxity. When the masseter muscles shrink from neurotoxin, it removes structural support of the lower face, which can exacerbate the appearance of loose skin and worsen the appearance of jowls and marionette lines.”
Dr. Nussbaum adds that when you minimize the appearance of a “bulging” masseter, people tend to focus on the next thing that's there, which is usually looser skin. “The neurotoxin itself does not cause jowling,” she emphasizes.
While this treatment is often referred to as “masseter Botox,” keep in mind that Botox is a trademarked brand name that’s become a catch-all term for all neuromodulators, like Kleenex is for tissue. The type of neurotoxin that’s used in the masseter muscles all comes down to your injector’s preference. “Since the masseter is such a large muscle, most injectors prefer products that have been shown to diffuse better, meaning they weaken the muscle more evenly,” says Dr. Lee, who prefers using Dysport. For her part, Dr. Nussbaum typically uses Botox. The neurotoxin I got was neither Botox nor Dysport, though it was one that’s FDA-approved.
But like all neuromodulators, it’s not FDA-approved for use in the masseter. Injecting into these muscles is an off-label usage of neuromodulator, which means the FDA (Food and Drug Administration) hasn’t approved injecting them into the jaw. This doesn’t make the practice unsafe—it’s pretty common for dermatologists to inject off-label, including for eyebrow “lifts” and “lip flips.”
It’s important to consult with your dermatologist to determine whether you’re a good candidate for injections in the masseter muscles. You should also consider the price of the treatment. Dr Nussbaum and Dr. Lee both generally use about 16 to 20 units per masseter (32 to 40 units total), which they say can cost anywhere from $500 to $1,500, depending on your location and provider.
My experience with masseter injections
The first time I got my masseters injected, I was 27. I have a rounder face, and I tend to clench my teeth when I’m stressed, so this seemed like a good way to give my jawline more definition and save my teeth at the same time. I figured there was no harm in trying it, and a few minutes later, 20 units of neuromodulator were injected into either side of my jaw.
I began to notice a difference in my facial structure about four weeks after that first appointment, which Dr. Lee says is typically how long it takes to see the full results. Call me vain, but I couldn’t stop looking at myself—as someone who has had a fuller face my entire life, the masseter injections gave the illusion that I had lost 10 pounds. I wouldn’t say that my jawline was sharp enough to cut glass, but it was certainly more defined.
The effects of those injections lasted around five months. Once I began waking up with a sore jaw again, I knew it was time to schedule another appointment. I visited a board-certified dermatologist (as a freelance beauty editor covering aesthetic treatments for potential coverage, I received the treatment gratis), and I expected the results to be even better than before.
While the injection itself was totally uneventful and the doctor made me feel at ease, I started to experience a bizarre side effect about a week later. My left ear constantly felt like it needed to be popped (like that feeling when you have water stuck in your ear), and no matter what I tried—cleaning my ears, chewing gum, or plugging my nose and blowing to pop my ears—the feeling wouldn’t go away. To be honest, I didn’t think much of it; this was around early October when the changing seasons always trigger my allergies, so I assumed this would dissipate in a few days. Only later did I realize it was the initial sign that something was wrong.
The effect on my smile appeared a week and a half after my appointment. But even then, I didn’t put two and two together to realize my masseter treatment was to blame. I came home after a night out with friends, and while I was taking my makeup off, I lost control of the left side of my smile. For the next hour, I ogled at my reflection and started to panic. The corner of my mouth slowly drooped every time I tried to grin. I convinced myself that all would be back to normal in the morning. Spoiler: It wasn’t.
Here’s the thing—I still didn’t think this had anything to do with my masseter. It finally clicked when I went back to the dermatologist for a touch-up on my forehead two weeks after the initial injection, which was five days after I first noticed my wonky smile. Weirdly enough, during that visit, my doctor told me how she had gotten masseter injections while in med school, which resulted in—you guessed it—a crooked smile. I listened intently as she explained there was nothing she could do but wait until the neuromodulator faded.
Long story short, don’t be like me: It’s absolutely imperative to convey any issues to your injector before, during, and after treatment.
Why an asymmetrical smile can occur from masseter injections
While one study conducted at the University of Pennsylvania School of Medicine and published in a journal, Dermatologic Surgery, showed that injecting botulinum toxins into the masseter can actually correct an asymmetrical smile, according to the dermatologists I spoke to, the exact opposite can occur if the placement is just a few millimeters off—specifically if the neuromodulator hits the risorius muscle, which is responsible for pulling up the corners of the mouth, explains Dr. Lee.
Aside from the exact location of the injection, the depth of placement also matters. “Smile asymmetry is more likely to occur if the injection was placed too superficially to the masseter or directed too close to the mouth or cheeks,” says Dr. Lee. “A few millimeters can absolutely make a difference.” This can occur if the needle itself is too short, and therefore unable to reach the proper muscle.
When it comes to the injection technique, Dr. Lee says it’s extremely important for your injector to feel your facial muscles when clenched and when relaxed to assess imbalances in the muscle or underlying bone. “From there, your practitioner should inject deeply into the muscle while angling the needle away from the risorius,” she says. “This helps minimize the risk of unintended diffusion and reduces the chance of affecting smile symmetry.”
Dr. Nussbaum also emphasizes that less is more. “You can always add more units later, but you can’t take any away.” The brand of neuromodulator has less of an impact and shouldn’t necessarily result in an adverse side effect unless you have an allergy. Above anything else, it’s crucial to only get injected by trusted board-certified dermatologists or plastic surgeons. My case is especially interesting because I did go to a dermatologist.
If you do end up with an asymmetrical or crooked smile as a result of masseter injections, find some peace of mind in the fact that it will fade eventually—in about three to five months, depending on the neuromodulator used. “The good news is that smile asymmetry from masseter neuromodulator is temporary, and actively using the affected muscles can help speed up recovery,” says Dr. Lee. Giving yourself regular facial massages and even chewing gum can accelerate the process.
Despite the harsh realities of my experience, I’d get my masseters treated again—and recently got a flawless re-up from a different dermatologist, Dr. Nussbaum. No deformed smile this time around! The treatment eased the jaw pain caused by excessive clenching and slimmed my profile. So, if you catch me beaming from ear to ear, just know I’m making up for five months of lost time.
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