I make an iced tea that is actually based on an herbal mix I use for pregnant women.
Kids and adults alike really like it. The main ingredient is Red Rassberry Leaves which are high in calcium and good for little ones tummy's too! Here's the recipe:
two handfulls RRL (or more to your liking)
1 TBSP rose petals
1- 2 TBSP hybiscus flowers (measures vary here depending on whether the dried flowers are whole or not)
1 bottle/can pure apple juice concentrate
Infuse the herbs in 1 litre boiling water for 4 hours. Strain into a 2 litre jug, squeezing all the liquid from the herbs.
Add 1/2 bottle apple juice concentrate. Mix well.
Add 1 litre cold water. Mix and refrigerate.
This comes out a lovely red colour (which is pleasing to kids) and the apple juice adds just enough sweetener to hide the sourness of the hybiscus. You can play around with quantities. If your son has cavaties, I would just be careful about the amount of apple juice you use.