The Collaborative International Dictionary of English v.0.48:

Self-destructive \Self`-de*struc"tive\, a.
   Destroying, or tending to destroy, one's self or itself;
   rucidal.
   [1913 Webster]

WordNet (r) 3.0 (2006):

self-destructive
    adj 1: dangerous to yourself or your interests; "suicidal
           impulses"; "a suicidal corporate takeover strategy"; "a
           kamikaze pilot" [syn: self-destructive, suicidal]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "self-destructive":
   baneful, bloodthirsty, bloody, bloody-minded, calamitous,
   cataclysmal, cataclysmic, catastrophic, consuming, consumptive,
   cruel, cutthroat, deadly, demolishing, demolitionary, depredatory,
   desolating, destroying, destructive, devastating, disastrous,
   doomful, fatal, fateful, fratricidal, gory, homicidal, internecine,
   murderous, nihilist, nihilistic, ravaging, red-handed, ruining,
   ruinous, sanguinary, slaughterous, subversionary, subversive,
   suicidal, vandalic, vandalish, vandalistic, wasteful, wasting,
   withering