Can Botox on crows feet cause muscle paralysis in other areas of my face?

To answer your question, yes, Botox injected in one area can affect muscles in other areas. This tends to muscle groups adjacent to the injected area. This is why it is important to follow post-care instructions strictly. Lying down within a few hours of the injection and vigorous exercise are some of the activities that will promote the unintended diffusion of Botox. In your case, however, a little caution is in order. The Botox would have to have diffused pretty far to significantly affect your smile. I suggest caution because Botox has been known to bring out signs of nascent neurologic disease and because your symptoms may have nothing to do with Botox. Although by laws of probability this is most likely due to the Botox, I'd see your primary physician. If it is the Botox, you will be back to normal when the Botox wears off. Bell's Palsy is a condition that tends to give symptoms similar to what you describe. Bell's Palsy is itself benign and tends to resolve without treatment. However, such things as a stroke, Lyme disease and many other conditions will mimick Bell's Palsy. A good neurological evaluation will put your mind at rest.