Does any local anesthetic cause some sedation in a patient?

Not in right dose. Local anesthesia is injected to cause numbness in a small area of the body, such as around a tooth before dental work. In proper doses, it causes no side effects at all. Sometimes lidocaine, one type of local anesthetic, is given directly into a vein to treat abnormal heart rhythms. This can cause brief side effects such as ringing in the ears or drowsiness, but these go away quickly.