I have used them on long (as in century plus) rides. I primarily rely on Cytomax on long/hot rides, however.
Out of curiousity though, what and how much were you otherwise drinking? Remember that the tabs will help with electrolyte replacement--which is important, don't get me wrong--but not dehydration. For that you need fluids. Also, what were you eating? Chills and dizziness can be a sign of bonking, too.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher