From a brief glance the Internet says they dealt with a lot of stuff including medicine. I figure ancient druids had apothecaries where they studied and practiced actual medicine for their day.
Can you imagine time-warping a druid from his tinctures and salves to modern day and showing him Witchblr?
"Like, so you mixed roots and plants with different materials and stuff? Hella crazy! I totes just put my left over lasagna in a jar, light a scented candle and asked Persephone to get frisky with me. Oh! Hold on a sec. My friend just texted me. Home gurl needs an incantation STAT!






There. Don't know why she she was coughing up blood but that emoji spell cures everything. No need for doctors. Anyway, so you were saying something about formulas?"