- Tanning addiction
- Technology addiction
- Temperance movement
- Teramine
- Texting
- THC (Tetrahydrocannabinol)
- Thorazine
- Thought field therapy
- Time line therapy
- Tobacco
- Tolerance
- Transactional analysis
- Transpersonal therapy
- Tranxene
- Trauma
- Trauma echo
- Trauma-focused cognitive behavioral therapy
- Treatment center
- Treatment episode data set
- Treatment plan
- Triazolam
- Trichotillomania
- Tricyclic antidepressants
- Triggers
- Tuinal
- Tweaker
- Twelve Steps (12 Steps)
- Twelve Traditions (12 Traditions)
- Twelve-step groups