Masseter Botox in Nashville: Jaw Slimming and FDA Status
Masseter Botox is an injection of botulinum toxin (BOTOX® Cosmetic is the brand most people mean) into the masseter, the chewing muscle at the angle of your jaw, to soften the look of a wide or square lower face. Today it is an off-label use, which means the FDA has not approved Botox Cosmetic for it. However, a federal review is now underway. Here is what that means for patients in Nashville, what a visit involves, and what to ask before you book.
What is masseter Botox?
The masseter is a thick muscle on each side of your jaw. You use it every time you chew. In some people it is larger, so the lower face can look broader or more squared off. Providers call this look masseter muscle prominence.
Botox Cosmetic (onabotulinumtoxinA) works by blocking the signal that tells a muscle to contract. During treatment, a trained provider injects small amounts into the muscle. The goal is a softer, slimmer-looking jawline. Importantly, Botox acts on muscle. It does not change bone structure or remove fat.
Is masseter Botox FDA-approved?
No. Not yet. This is the most important fact to understand before you book, so here is the exact status.
- Current label: The FDA-approved prescribing information for Botox Cosmetic (revised October 2024) lists four uses in adults: moderate to severe frown lines, crow’s feet, forehead lines, and platysma (neck) bands. Masseter is not on that list.
- The filing: On August 4, 2026, Allergan Aesthetics announced that the FDA accepted its application to add a new indication for marked to very marked masseter muscle prominence in adults. Acceptance means the FDA will review the application. It is not an approval.
- The timeline: The company’s announcement did not give a decision date, so nobody can say when, or whether, approval will come.
- The studies: According to the company, two phase 3 studies (M21-416 and M21-417) met their main goals compared with placebo. These results come from the manufacturer, and the FDA has not yet ruled on them.
You can read the announcement in the Allergan Aesthetics press release and check the current approved uses in the official Botox Cosmetic prescribing information.
What does off-label mean for you?
Off-label means a licensed provider uses an approved medicine in a way that is not listed on its label. It is legal, and it is common across medicine. However, it puts more weight on your provider’s judgment, and the use has not been through FDA review for that purpose.
The Botox label itself carries a warning about serious reactions reported after unapproved uses. For that reason, you should be told plainly that this use is off-label. Ask your provider to explain the off-label status before any injection, and ask for it in writing.
What to expect at a masseter Botox visit
The consultation
First, your provider should look at your face from several angles and feel the muscle as you clench. A wide jaw can come from muscle, bone, or fat, and Botox only addresses muscle. In addition, you should review your medical history, your medications, and any history of jaw or dental problems.
The treatment
The injections are quick. They use a very fine needle. Your provider decides the number of injection points and the amount for your anatomy. Because this use has no FDA-labeled dose, you should expect an individualized plan rather than a fixed formula.
Afterward
Your provider will tell you what to avoid in the first hours and days. Ask for realistic timing, too. The label’s only stated duration is for frown lines, not the jaw, so a trustworthy provider will not promise a specific timeline or result.
Who is a good candidate for masseter Botox?
People who feel their lower face looks broad because of a strong masseter muscle are the usual candidates. On the other hand, some people should not have treatment. The label lists a known allergy to any botulinum toxin and an infection at the injection site as contraindications. Smiley Aesthetics does not treat during pregnancy or breastfeeding, and a neuromuscular condition can raise the risk of side effects. Tell your provider about all of these.
Risks and side effects of jaw slimming with Botox
Every Botox product carries a boxed warning about distant spread of toxin effect. The effects of the toxin can spread beyond the injection area, from hours to weeks after treatment. Symptoms can include general muscle weakness, double vision, drooping eyelids, trouble speaking or swallowing, and trouble breathing. Swallowing and breathing problems can be life-threatening. Get medical help right away if you notice any of these.
Localized effects such as tenderness or bruising at injection sites can happen with any injection. Because the masseter is a chewing muscle, ask your provider what changes to expect when you eat. Finally, the label states that safety and effectiveness are not known for dosing more often than every three months, so do not stack treatments to speed up results.
Jaw clenching and teeth grinding: what is different
Some people ask about Botox for teeth grinding or jaw tension. The pending FDA application is about the appearance of masseter prominence only. Jaw pain, clenching, and grinding are medical and dental questions, and they deserve an evaluation by your dentist or physician first.
Questions to ask before you book
- Who will perform the injection, and what is their training?
- Is this use off-label, and will I sign a consent that says so?
- Is my wide jaw caused by muscle, or would bone or fat be a better explanation?
- What side effects should I expect, and what should I do if I have a concern?
- What will it cost, and how many visits should I plan for?
For pricing context, see our Botox cost guide for Nashville. If your goal is added structure along the jawline rather than slimming, our dermal filler cost guide explains that different approach.
Frequently asked questions about masseter Botox
Is masseter Botox FDA-approved?
No. The FDA accepted an application for review on August 4, 2026, but it has not approved Botox Cosmetic for masseter muscle prominence. Providers use it off-label today.
Does Botox change my bone structure?
No. Botox acts on the muscle by blocking the nerve signal. It does not change bone.
Is it the same as jawline filler?
No. Botox relaxes a muscle, while a filler adds volume or structure. They address different concerns, and some people discuss both with their provider.
How much does masseter Botox cost in Nashville?
The cost depends on the amount your provider uses for your anatomy. Our Botox cost guide explains how pricing works, and you will get an exact quote at your consultation.
Can it treat teeth grinding?
The pending FDA application covers the appearance of the jaw only. Talk with your dentist or physician about grinding or jaw pain.
Botox, Letybo and Dysport are all neurotoxins. See how the three compare and what we charge per unit.
Book a Botox consultation in Nashville
If you are curious about jaw slimming, start with a conversation. A Smiley Aesthetics provider can assess your face, explain what is approved and what is off-label, and tell you honestly whether Botox is the right fit. Book a consultation at Smiley Aesthetics in Nashville.
This article is for education only and is not medical advice. Treatment decisions should be made with a licensed medical provider who knows your history. Results vary, and no outcome is guaranteed. FDA status described here is accurate as of the publication date and may change.
