We started doing formula when LO was 7-8 months (now he's 10.5 months).
These days after making a 5.5 oz bottle, LO would drink only 1-2 oz, and I found myself throwing bottles of bottles (of expensive formula) away! So on Friday, after he drank only 1 oz before bedtime, I put the bottle back in the fridge, and gave it to him when he cried on and off at 12-1am. In fact that's what I did with breastmilk and it's always been fine back then. I am not sure if that's the reason why but he start throwing up in the morning. That was yesterday. He threw up this morning too.
This is the 2nd time we have vomiting ever with LO. The first time was 2 weeks ago and I really don't know why / what triggered this. I wonder if it were the formula or if it were just some other food poisoning / allergy? I know the box says throw away formula within an hour after feeding has begun, but do you ever save formula that your LO didn't finish?