Ketamine therapy is the use of ketamine as an antidepressant, anti-anxiety, for post-traumatic stress disorder (PTSD) and psychiatric disorders. Ketamine is preferred over traditional antidepressants because it is fast acting and very effective. Also, traditional antidepressants cause nausea, drowsiness or insomnia, constipation and weight gain - which are not side effects of ketamine. However, ketamine is not the first line of treatment, it is only prescribed when other antidepressants don’t work. Two main types of ketamine are used to treat major depression: Racemic ketamine and Esketamine (Spravato). Racemic ketamine (also called intravenous ketamine) is administered as an IV infusion in the arm, and typically the effects last for anywhere from days to weeks. It is a mixture of two mirror-image molecules: “R” and “S” ketamine. Esketamine is given as a nasal spray and uses only the “S” molecule. There is no conclusion yet on how ketamine exerts anti-depression benefits, but it is thought that ketamine binds to the N-methyl-D-aspartate (NMDA) receptors in the brain. This binding causes an increase in the amount of a neurotransmitter called glutamate in the spaces between neurons. Glutamate then activates the AMPA receptor. This results in the release of other molecules that help neurons communicate with each other along new pathways. Known as synaptogenesis, this process likely affects mood, thought patterns, and cognition. Ketamine may also influence depression by reducing signals involved in inflammation, which has been linked to mood disorders. Ketamine has addictive properties and must only be used with the help of a doctor.