Botox was accidentally injected into a vein on side of my temple, had massive bruising afterwards. Will this cause damage?

You should be fine in 7-10 days when the bruise goes away. Many patients bruise with Botox.  Best of luck to you. 

Thank you for sharing your question. You should not have any long term problems from being injected with Botox even if a vein was hit. The bruise should improve over a week or two. Make sure to see experienced injectors for your treatments. Good luck,