I always ask our pedi before giving our kiddos any OTC meds they haven't had before. She's recommended dosages for some meds that say they aren't recommended for children under 2 yrs when our kids were babies, and others that say they are fine, she's given a no-go.
Dosages are always based on weight. My boys are both very big for their age (6 in a couple of weeks, and 10 mos), whereas my cousin (10) and my nieces (8, 5, & 7 mos) are all small for their ages. It makes a big difference!
The best thing I've found recently is our naturopath who can clear allergies & help with more natural remedies for things. They've actually inspired me to start studying naturopathy myself due to all the wonderful things they've done for me & my kiddos (the little guy & the baby on the way wouldn't even exist if not for them!). They are in the Heights if you're interested.