Can Botox in the masseter cause hearing loss?

From my experience, it is extremely unlikely that your Botox injection has caused your vertigo and hearing loss.  I would recommend scheduling an appointment with an ENT doctor to determine what is causing your symptoms.  

Thank you for your question JessicaC1014. 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 where the entire medical history is reviewed. However, I hope the information provided here is useful.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.
The safety record of Botox is well established. The product has been used for over 20 years for a variety of treatments with minimal side effects. Botox is amongst the safest treatments for treating facial wrinkles.While Botox is one of the safest treatments offered, there are some situations where it is not appropriate. These include anyone who has an allergy to any of the inactive ingredients or who has had an allergic reaction to any botulinum product including Botox, Dysport, Xeomin, or Myobloc. The safety and efficacy of Botox has not been established in women who are pregnant, trying to become pregnant, or breast feeding. Therefore, women in these categories are advised to wait until breast feeding is completed prior to having a Botox treatment. Botox should not be placed in the skin on the site of an infection. Those who are taking an aminoglycoside antibiotic, an anesthetic, D-penicillamine, antimalarials, or immunosuppressants should not be treated, nor should those who have undergone chemotherapy within the previous six months. It is important to avoid blood thinners before and after a treatment. These include both prescription and non-prescription medications such as warfarin (coumadin), aspirin, ibuprofen, alcohol, fish oil, vitamin E, and ginko biloba. Those with conditions that affect muscles and nerves such as amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), myasthenia gravis, or Lambert-Eaton syndrome should not undergo Botox treatments.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.If I had a patient with the concern described here I would say that the vertigo and hearing changes are unrelated to the Botox treatment and I would recommend consulting with an ear specialist.
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!