The disclosure provides methods for the for treatment of psychosis, such as schizophrenia, or depression (such as bipolar depression) and/or anxiety, comprising administering to a patient in need thereof, (i) a 5-HT2A or 5-HT2A/D2 receptor ligand, for example a substituted heterocycle fused gamma-carboline as described herein, in free, pharmaceutically acceptable salt or prodrug form, and (ii) a nitric oxide donor, separately (sequentially or simultaneously), or in combination (e.g., in a fixed dose combination).