Can Botox Cause Loss of Smell and Taste?

As of this writing, I am unaware of these findings in the literature.  Botox is injected into the specific muscle.  Where it is commonly injected, loss of smell and taste should not be an issue.  

This is not an associated side effect of Botox. When injected properly by an experienced and board certified physician, Botox can yield a fantastic result and the chances of any negative side effects occurring are minimized. I hope this helps, and I wish you the best of luck.

For all side effects and adverse reactions to cosmetic Botox, I'd refer you to their website listed below. I haven't read nor heard of Botox causing loss of smell or taste.

Botox works on motor nerves (nerves responsible for movement) but not on sensory nerves, such as those for smell and taste.  So, there should be no loss of smell or taste after a Botox treatment.  

However it can cause an array of idiosyncratic reactions.  Loss of smell would be very unusual.  However I think you should bring your symptoms to the attention of your doctor.  This symptom warrants medical attention to determine the cause.