I had masseter Botox 3 days ago, when will I feel the effects?

Dear citizen22,Botox is generally an on off switch for muscle activity. Finding an experienced physician injector is your best bet. Most of patients see first changes after 4-7 days and the final results after 10-14 days. It depends on the amount of Botox and area where it is injected but it usually last for 3-4 months.Daniel Barrett, MD, MHA, MS 
Certified, American Board of Plastic Surgery  
Member, Am. Society of Plastic Surgery

Dear citizen,
Thank you for your query. 
Botox for masseter is a common procedure done in Asia. Here is the information you requested.
Botox 
- 1. Feel effect within 1 week. Meaning your jaw feels more tired when chewing food.
- 2. See visible changes in 1 month. Meaning the jaw slimming effect takes place.
- 3. Hence what you experienced is normal. ) 
Hope this helps.
Dr Daniel Chang