The main types of anti-depressant drugs are: -Selective serotonin reuptake inhibitors (SSRIs) which are the most common and include: Prozac (fluoxetine), Celexa (citalprom), Zoloft (sertraline), Luvox, Lexapro and more; -Serotonine-norepinephrine reuptake inhibitors (SNRIs) - they include Effexor (venlafaxine) and Cymbalta. The dosage for these anti-depressant drugs might need tapering as they have proven to cause a series of side effects; -Noradrenergic and specific serotonergic anti-depressants (NASSAs) – these anti-depressants are used in order to increase the serotonin neurotransmission by blocking adrenergic receptors. The only substance used for NASSAs drugs is mirtazapine (Avanza, Remeron). However, this new method brings weight gain and increased appetite as side effects; -Norepinephrine (noradrenalin) reuptake inhibitors (NRIs) – positively affect motivation and concentration power. Examples: Edronax. -Tricyclic anti-depressants (TCAs) –have a lot of side effects such constipation, heart attacks, urinary retention, sexual dysfunction and confusion. TCAs are not considered safe anymore.