Mirtazapine significantly improves pre-existing symptoms of nausea, vomiting, diarrhea, and irritable bowel syndrome in afflicted individuals.[98] Mirtazapine may be used as an inexpensive antiemetic alternative to Ondansetron.[33] In conjunction with substance abuse counseling, mirtazapine has been investigated for the purpose of reducing methamphetamine use in dependent individuals with success.[3][4][5][6] In contrast to mirtazapine, the selective serotonin reuptake inhibitors (SSRI), serotonin–norepinephrine reuptake inhibitors (SNRI), Monoamine oxidase inhibitors (MAOI), and some Tricyclic antidepressants (TCA) increase the general activity of the 5-HT2A, 5-HT2C, and 5-HT3 receptors leading to a host of negative changes and side effects, the most prominent of which including anorexia, insomnia, sexual dysfunction (loss of libido and anorgasmia), nausea, and diarrhea, among others.