This is the most common side effect. Because your lip and cheek feel like a piece of steak, you chew on them without realizing it. Hours later, you will find a swollen, raw spot inside your mouth. Tip: Check a mirror every few minutes while eating after a filling.

Sometimes the injection hits the facial nerve by accident. You might find you cannot blink one eye or smile on one side. Do not panic. This is not a stroke. It looks scary, but it is just the anesthetic blocking the motor nerves. It wears off in 1 to 3 hours.

If your heart does not stop racing after 10 minutes, or if you see any blue discoloration of your skin, call your dentist or go to urgent care.

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