Healthy medications I say I see in units of mass (6)
I believe the answer is:
tonics
'healthy medications' is the definition.
'tonics' can be an answer for 'medications' (tonic is a kind of medication). I am not certain of the 'healthy' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for tonics that I've seen before include "Potions to strengthen and invigorate" , "Medicines or drinks with invigorating effects" , "contents of medicine cupboards" , "Pick-me-ups" , "Keys" .)