I've had 2 separate Botox injections (3-4 months apart). I've developed dry mouth recently.

I'm not sure where you had your injection. Botox injections to the masseter could cause dry mouth, but it would resolve in a week or two, but this would be extremely rare. If Botox was injected somewhere else, it's unlikely it is due to your injection. If it persists, I recommend getting a formal evaluation with your Doctor to determine cause. 

Thank you for your question. You do not mention where you received your injections. If you had Botox injected into the masseter muscle then it can cause dry mouth. However, this would resolve in 1-2 weeks. If you had Botox injected anywhere else it is very unlikely to cause dry mouth. If this continues I recommend having this evaluated by your doctor to determine the cause. Best of Luck!