Meg- my Lila had a little sniffle before her immunizations, and afterwards it developed into a full-on cold... She was alternately sleepy (looong stretches of sleep) and cranky/restless afterwards, I gave her panadol to help with the little fever and the aches that I'm positive she had. It lasted a few days, I'm sure would have been less so had she not been a bit sick beforehand. I'd say just make sure you have some baby panadol around.