How long after botox to masseter do you notice results of slimming face?

Most patients will start to see results within about two weeks after their Botox injections. There are a couple of challenges in treating the masseter muscle that need to be addressed. First, it can be difficult to predict just how much Botox should be used to achieve the desired effect since you are gauging the dosing amount by the size of the muscle. Second, it can be more difficult to evaluate improvement, since you are looking for changes in the size of the contour, rather than the reduction of visible lines. The best way to determine if the medication is working is by studying your before photos and comparing them to the current facial profile.

Some slimming of the face can begin about 2 weeks after a Botox treatment to the masseter muscle, but the maximum effect can take 2-4 months.  

I have been treating hypertrophied masseter muscles for many years now for both aesthetic reasons in Asian women and in general for hypertrophy due to constant teeth grinding (bruxism). When the appropriate doses and sites of injection are chosen, this procedure, advanced by efforts of aesthetic dermatologists over the past two decades has proven quite successful both for aesthetically slimming the lower face and for treating discomfort from bruxism. In my experience, most people see results within under two weeks time, often even within the first week following treatment.  

It can take six to eight weeks to see the slimming in the jawline from your treatment. Other symptoms such as jaw clenching should improve a week or two after injection. I've included a video on how neuromodulators like Botox work that I hope you find helpful.

Facial nerve toxins such as Botox and Dysport have onset of action anywhere between 2 days and 10 days, so it may be too early to judge whether you have been injected with enough Dysport to relax the masseter muscle.  In our practice we recommend a evaluation in 2 weeks to make sure the appropriate affect has been achieved, and to see if you need a touch up treatment at that time. Best of luck

Thank you for your question sisteract. I understand your concern. Botox is a purified protein used to address wrinkles associated with facial expression. When injected into the skin Botox will relax the muscles and smoothen out the overlying wrinkles. The most common areas of treatment are in the upper face. These include the horizontal lines seen on the upper forehead when one raises the brows, the vertical lines seen between the brows when one frowns (frown lines), and the crow's feet seen around the eyes when one smiles.
It is difficult to make an assessment without a formal exam in the office where I can view the skin in multiple angles and observe wrinkles formed with facial expression. However, I hope the information provided here is useful.The pivotal studies demonstrated that the peak results are seen 14 days after the treatment and most people enjoy their results for 3-4 months. At that point, a maintenance treatment is recommended. While some people start to see results as early as the next day, it can take two weeks for full results so patience is important. We have our patients return two weeks after their treatment to assess their results via photographs. At that time additional units may be added if necessary. 
Botox can be placed in the masseter muscle in the lower face to contour the lower face and address pain associated with TMJ. In this area 20-40 units of Botox are used per side. Depending on the reason for the enlargement of the muscle, permanent results may be achieved. For example, some people have a habit of grinding, clenching, or biting their teeth subconsciously. Often times this happens in their sleep when they are not aware of it. Botox placed in this muscle will relax the muscle and the grinding, clenching, and/or biting will decrease. This will reduce the size of the muscle. If the brain gets accustomed to this and the person stops grinding, clenching, or biting, then the muscle will not become enlarged or as enlarged again. However, if the habit starts again, the muscle will likely get larger.

To determine if someone is a good candidate for this treatment it is necessary to look at a person’s lower face when biting and comparing it to when the person is not biting. If a bulge is seen on the outer portion of the jawline, then the person is likely a candidate. It can also be felt with the fingers when biting.
In my experience patients notice the slimming effects in the lower face approximately two weeks after the treatment. If too low a dose was used then additional units may be required to see improvement.With any injection, there are risks such as pain, bleeding, bruising, redness, swelling, tenderness, and infection. We take special precautions to minimize these risks such as using a painless technique. We also treat bruises with a laser as early as the next day. Bruises usually resolve within two weeks if untreated. After a laser treatment bruises usually resolve in 1-3 days, but may still take two weeks for full resolution. In addition to these risks, with Botox there is also a risk that the product spreads or diffuses to nearby structures. Spread to nearby muscles can lead to side effects such as the temporary appearance of droopy eyelids or a temporary asymmetric smile.

After a Botox treatment, I recommend that my patients avoid heat exposure, alcohol consumption, and strenuous exercise for 24 hours and not lie down flat for four hours. This is because all of these activities may possibly lead to the movement of the product and consequent side effects such as droopy eyelids. Although there have been no definitive studies shown that these actually occur and some physicians do not provide such aftercare instructions, in the absence of data I err on the side of caution and recommend that my patients avoid such activities.

Please consult with a doctor for specific recommendations. Good luck!

The direct effects Botox has on your masseter muscle will take about 2 weeks to be realized.  However, as your masseter muscle will be been weakened, it will continue to slim as long as the Botox takes effect.  So you will see initial results after two weeks, but continued improvement until your procedure wears off.

Botox is fabulous to reduce the masseter muscle and the more times you do Botox, the more the muscle will weaken and the better the results. The results of Botox generally take two weeks.  Please consult an expert in Botox in the masseter muscle since this is a specialized use of Botox.  Best, Dr. Green

Thanks for your question! The final result of botox is usually expected within 2 weeks of treatment. The degree of facial slimming depends on how prominent the masseter muscles are to begin with and the presence of any other factors (such as fat) that may also be contributing to a wider face. Often with masseter injection, the improvement may not be as obvious since the change is gradual and you are not looking at movement or lines like you do in the forehead. Consider asking to view your before and after photos as this frequently shows how much of a difference the treatment made. Good luck!

it takes approximately two weeks to see the result of facial slimming using Botox. I hope this helps and good luck from New York City