Why does face twitch both right and left sides upon tapping?

Calcium issue: Possibly you have low calcium levels or perhaps metabolic problems decreasing ionized calcium.. This can result in a unilateral facial twitch upon stimulation (chvostek's sign). Check with your doctor.

If you tap then : Tapping the tendons of facial muscles can elicit a reflex contraction of that muscle. Similar to the famous patellar knee jerk reflex, only of a much smaller muscle. Good work in discovering a little known clinical sign!