What are the most common symptoms of scorpion sting?

Variable discomfort. A scorpion sting may cause a painful, tingling, burning or numbing sensation at the sting site.The symptoms may be mild. Rarely, however, a person may experience a more serious reaction including widespread numbness, difficulty swallowing, a thick tongue, blurred vision, seizures and difficulty breathing. These symptoms are considered a medical emergency and require immediate medical attention.
Depends. In usa: first, pain, then depending on the grade, cranial nerve dysfunction such as blurred vision, abnormal eye movements, slurred speech, tongue quivering, and  excessive salivation, or somatic skeletal neuromuscular probs such as restlessness, fasciculations, shaking and jerking of the extremities, alternating opisthotonos (arching of the back), and emprosthotonos (forward flexion).