Age. Reaction of a baby to teeth vary depending on age. Teething to infection to a plethora of other diagnoses is feasible. A complete exam is important.
Very individual. The symptoms of teething are highly variable between children. Some children get teeth without any symptoms at all, while others are just miserable. The most common symptoms are excessive drooling, mildly elevated temperature, diarrhea, restlessness and irritability. Cold teething rings, pain medications and messaging the gum areas can help somewhat. A natural treatment named camilia can help.