Does Botox Cause All over Body Weakness?

Get a second opinion from a neurolopsych doctor about side effects.
Ideally a functional-physiologic approach to TMJ disorders is indicate.  Look into neuromuscular diagnostic orthotic  and treatment of myofascial pain with Spray and Stetch (RX) at home, trigger point injections, physical therapy, oral myofunctional therapy, trigger point myotherapy. prolotherapy, ozone therapy, topical tricyclis and especially Self-Administered SPG Blocks.
All TMJ patients should be evaluated for sleep disordered breathing.
Please visit web reference to hear about patients treated by correcting physiological condition instead of injecting dangerous neurotoxins.

Ira L Shapira DDS, D,ABDSM, D,AAPM, FICCMO
Past Chair, Alliance of TMD Organizations
Diplomat,  Academy of Integrative Pain Management
Diplomat, American Board of Dental Sleep Medicine
Regent & Fellow, International College of CranioMandibular Orthopedics
Board Eligible, American Academy of CranioFacial Pain
Dental Section Editor, Sleep & Health Journal
Member, American Equilibration Society
Member, Academy of Applied Myofunctional Sciences
Member, Academy of Cosmetic Dentistry

generalized muscle weakness certainly is not a common side effect of Botox, especially if the symptoms develop six weeks after the treatment. That is not to say, that you aren't having these symptoms and it is possible, as one could not say it is impossible, for the botox to have caused it in you. The neurologist may do tests to determine if there is a true weakness and tests may determine that it is a coincidence and there is a different cause for your weakness.

The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice.  The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs. If you are experiencing a medical emergency proceed to your nearest emergency room.

The two are unrelated in my opinion and cosmetic Botox injected locally will not have a systemic effect - see your primary care doctor for guidance and a thorough evaluation to make sure there is nothing else going on with you.

Botox may cause side effects, but many people have no, or minor, side effects. Common side effects can include stiff or weak muscles at or near the injection site. However, since you are experiencing all-over body weakness, the two may be unrelated. I would schedule an appointment with your doctor to pinpoint the cause of this. Best of luck.

Assuming the botox you received was for TMJ and it was within the recommended dosage, then it should not give you the sympotoms your discribing.