Synonyms for Palliative (same or very similar meaning)
WordNet sense 1 (remedy that alleviates pain without curing):
alleviant, alleviatorWordNet sense 2 (moderating pain or sorrow by making it easier to bear):
lenitive, mitigative, alleviative, alleviatory, mitigatoryWordNet sense 3 (lessening in intensity or strength):
moderatingFrom the ODE community, based on WordNetadd/edit