Hi...
I would have to had missed a big dose of medication to feel different. Like my morning or evening dose, but most of the time I am that active that any side-effects go unnoticed, or blamed on other things.
Lethargy is probably the most frequent, then a headache - but then again, that is brought on by physical activity (such as running around, school, dancing etc)...
Never have I felt like I wanted to vomit...I've been dizzy - but thats because I am anemic, and the headaches are generally because I suffer from migranes...So I wouldn't really say that all of my physical symptoms are brought on by missing a dose here and there.
Something I have noticed though is that at all the times that I have missed a dose, I get massive muscle cramps...Its something to do with low sodium levels, and that combined with long distance running is a recipe for pain.
Other than that, I don't think that missing a dose is worthy of a major panic attack - its rather unnoticeable in terms of physical changes for me. If however, it would happen more than once in a day then that is more likely when there would be greater implications. I haven't tried that, so I don't have any feedback on that, but I highly doubt you'll forget to give your sons whole daily dosages to him!
Take care
Annalise