Ok, according to the situation you described, the two-year-old baby ate half a betel nut, and eat areca's excessive reaction would produce poisoning symptoms, ranging from excitement, glassy eyes, trembling all over, unsteady walking and strange behavior.

Guiding opinions:

Comments and suggestions, if you just eat by mistake, please pay more attention to observation and drink plenty of water. If you have obvious discomfort, you should seek medical treatment immediately. If you don't have obvious discomfort, you don't need special treatment.

The above are suggestions on the question "What should I do if a two-year-old child eats half a betel nut?" I hope it will help you and wish you health!