BABY HAD CAFFEINE, HELP

Okay so my dad left his coffee out and his gf wasn't watching my little sister (she's 1). So when he came back to the living room, she had taken a drink or maybe more of his coffee (they could tell by the little bit she had dribbling down her chin). I wasn't down stairs so I have no clue how much she drank. Could the caffeine hurt her? Should she see a doctor to be sure? She's really fussy and upset which isn't normal because she's always happy and smiling. I'm wondering if it gave her a stomach ache, but I don't know if that's all that will happen. Any ideas???