My interpretation was that ketracel-white was both chemically addictive AND needed for the specific amino acid (or whatever it was that their body could not produce).

This, to me, meant that any Jem’Hadar that wanted to drop ketracel-white would go through withdrawal and then die painfully. For most Jem’Hadar the two different aspects would be indistinguishable from each other and viewed as one effect.