What will happen if augmentin (amoxicillin and clavulanate) is given to a baby every 6 hours instead of 8 hours?

Higher levels: They will simply get more antibiotic in their system. It is unlikely to produce any significant harm, other than predisposing them to yeast infections or cl difficile, but that may happen anyway with the prescribed dosage schedule.

Run out of meds: The med sticks around in the system long enough that every 8-12 hours is common for dosing. The amount dispensed is usually enough to give the prescribed dose at the prescribed interval. Give it more often & you run out sooner. That may create problems.