My 2 year old drank dish soap! Help!?!?

my grandma fixed my son some milk after washing his cup out. He was thirsty but didnt want it. He finally handed it back and decided he wanted tea. The cup was mostly full so i decided to look inside...which i smelled the scent of oxy clean dawn dish soap or w/e she had and she hadnt rinsed it all out when she poured the milk in. He is 2 years old. I got a clean cup and rinsed it and fixed him tea and he drank it. He will be ok right? Is there anything i should do? It wont hurt him will it? Help...thanks!