I was on Lexapro and had the jaw clenching-thing...and teeth grinding. I was chewing the inside of my cheeks and lips and finally went to the dentist and had a mouth guard made...bit through it. And yes, it was painful and caused headaches. But it went away eventually. When I weaned off the drug the same thing happened. Yawning is also common. I was told to always take it in the morning also to prevent insomnia. Some people become sedated on this class of drugs intil it kicks in but it was just the opposite for me...very hyper. That went away also.
Donna