If you accidentally give your baby cold formula, it’s unlikely to have negative consequences. Just be sure to switch back to the warm formula next time. However, if the formula was previously heated, it should be disposed of. “Formula should only be heated once,” says Whitmore. “So if a parent plans to heat cold formula, they should make the formula at room temperature before storing it in the fridge. You should not heat formula, then refrigerate, then heat again.”