Every certified Organic chicken for sale at every farm gate, health food shop or grocery was raised without medication! So sure you can!
We raise all ours on unmedicated organic feed following the Canadian organic guidelines, and all organic feed would be unmedicated whatever side of the border you're on.
What we DO is this:
1.sanitize the pen you use for brooding. (hydrogen peroxide is what we use)
2.put a 1" layer of well composted manure (ie so composeted that it is mostly soil) on the floor of the brooder.
3. follow this by a 4" layer of fresh shavings.
4. brood as usual
5. mix the first 3 days feed with 50% sand, from the ground outside somewhere.
We do this so that the guts of the chicks are colonized with beneficial bacteria. It is also supposed to give them coccidia resistance. I read a really old article based on a study done in the 40's on raising chicks on deep litter once, stating that chicks have better gains when exposed to beneficials in the deep litter. I think this does the same. We have never lost a young chick.
I also think it is important to use a feed blended for use in an organic system which has the mineral blends and probiotics included to support a high functioning immune system. We use Homestead Organics. If you can't get an organic feed where you are, you could order in the mineral premix by mail, and blend it with straight grain (corn, pea, soy, wheat ect) making sure you aim for the right protein percentage in the grains.
Good Luck!!