Most people need 20 to 30 units of Botox per side of the jaw, for a total of 40 to 60 units per session. But the right number depends on why you’re getting it, how large your jaw muscles are, and whether you’ve had treatments before. Dosages can range from as low as 20 units total to over 80 units total, so the spread is wide.
Typical Units by Goal
The masseter is one of the strongest muscles in your body, and it can vary dramatically in size from person to person. That’s why there’s no single “correct” dose. Instead, providers work within ranges based on what you’re trying to achieve and how bulky your jaw muscle is.
For cosmetic jawline slimming with a smaller or average-sized muscle, 20 to 25 units per side (40 to 50 total) is a common starting point. If you have a stronger or more prominent jaw and want moderate slimming, expect 25 to 35 units per side, or 50 to 70 total. For significant slimming of a large, bulky masseter, providers often use 30 to 40 or more units per side, reaching 60 to 80+ total.
Some cosmetic practices recommend even higher doses for jawline reshaping. One surgical practice notes that 70 to 100 total units may be necessary for noticeable slimming in patients with strong jaw muscles, particularly when dramatic contouring is the goal.
Units for TMJ and Teeth Grinding
If you’re getting masseter Botox to manage jaw clenching, grinding (bruxism), or TMJ pain, the dosing tends to start around 25 to 30 units per side. Mild to moderate cases typically fall in the 50 to 60 unit total range. Severe bruxism or significant jaw tension often calls for 30 to 40+ units per side, bringing the total to 60 to 80 or more.
A minimum of 50 total units is a common recommendation for therapeutic TMJ treatment. Going too low can leave you with underwhelming relief, since the muscle needs enough weakening to actually reduce the clenching force that’s causing your symptoms. If your first treatment doesn’t fully resolve your pain or grinding, your provider will likely increase the dose at your next session rather than have you come back sooner.
Why Dosing Varies So Much
Three main factors drive the unit count up or down: muscle size, gender, and how your body has responded to previous treatments.
Muscle thickness is the biggest variable. Providers often assess this by feeling the muscle while you clench, and some use imaging to measure it precisely. If one side of your jaw is thicker than the other (which is common), you may receive a slightly higher dose on that side to keep things symmetrical. Research on patients with moderate to severe masseter prominence found that higher doses of 40 or more units per side produced more dramatic results that also lasted longer.
Gender plays a role because men generally have more muscle mass in the jaw. While women typically start at 20 to 30 units per side, men often need 30 to 40 units per side or more to see the same effect. This isn’t a hard rule, though. A woman who clenches heavily may have a masseter as thick as the average man’s.
Treatment history matters too. Your first session is essentially a test run. If you’ve had several rounds and your muscle has already started to shrink from repeated treatments, you may need fewer units to maintain your results over time.
What to Expect After Treatment
Masseter Botox works differently than forehead or crow’s feet injections. You won’t see changes in two or three days. On average, the muscle starts softening around weeks two to three, with real changes becoming visible by week four. Full results, particularly the slimming effect, take about six weeks to show because the muscle needs time to gradually shrink from reduced use.
If you’re treating bruxism, you’ll likely notice reduced jaw tension and less morning soreness before any visible change in your jawline shape. The functional relief tends to arrive a bit earlier than the cosmetic payoff.
How Often You’ll Need It
Plan on returning every three to four months for your first few sessions. The muscle gradually regains strength as the Botox wears off, and you want to re-treat before your clenching or jaw fullness fully returns. After several consistent treatments, many people find they can stretch their appointments to every four to six months because the muscle has partially atrophied from repeated weakening.
Let your symptoms guide timing rather than sticking to a rigid calendar. If your jaw still feels relaxed and your results look good at the four-month mark, there’s no reason to rush back in.
Risks of Incorrect Dosing or Placement
The most commonly reported side effect is an uneven smile. This happens when the Botox spreads from the masseter into a nearby muscle called the risorius, which helps lift the corner of your mouth. The result is a temporary asymmetry that’s most noticeable when you grin. It resolves as the Botox wears off, but it can take weeks.
The risk increases with injections placed too superficially (close to the skin surface rather than deep in the muscle) or with high volumes injected at a single point. Skilled providers inject at the right depth, beneath the fat layer and into the muscle fascia, and distribute the dose across three to four injection points per side. Weakened bite force is another possibility, especially at higher doses, though most people adapt quickly and don’t notice difficulty with normal chewing. Choosing an experienced provider who regularly treats the masseter is the most reliable way to avoid these issues.