What causes spasm at corner of mouth?

Spasms at the corner of the mouth can be caused by various factors, including muscle fatigue, stress, or anxiety. Neurological conditions such as Bell's palsy or facial nerve disorders may also lead to involuntary muscle contractions. Additionally, deficiencies in certain vitamins, like B12, and excessive caffeine or alcohol intake can contribute to this issue. If the spasms persist, it's advisable to consult a healthcare professional for a thorough evaluation.