I am going to get howled down for this. My own personal experience with SSRI's I would rate as the most horrible period of my life; that was 20 years ago when they were touted as a miracle cure. They are for some but not for all. It can be life changeingly positive for some and for others like me; not so much.
Recent studies have shown that social phobia is linked linked to high levels of serotonin. SSRI's then further aggravate the social phobia/anxiety. Drugs.com will not allow me to link to external sites so you should google "SSRI's and social anxiety or social phobia" which will explain in detail. Only read the articles from June 2015 onwards. Most doctors are not up to speed with their reading.
Partial quote below attributed to: Source: Frick A, Åhs F, Engman J, et al. Serotonin Synthesis and Reuptake in Social Anxiety Disorder: A Positron Emission Tomography Study. JAMA Psychiatry. 2015.
"Overly-Sensitive to Fear
To discover the truth, they used brain scanning technology, PET scans, to measure serotonin in the brains of volunteers with social phobia. Essentially, then, they tracked the chemical signals transferred between cells in the brain.
Communication within the brain works like this: Nerve cells release serotonin into the space between nerve cells. Then, serotonin attaches itself to receptor cells. Following this, serotonin is released from the receptor and returns to the original cell.
The researchers discovered patients with social phobia were producing too much serotonin in the amygdala. This brain region, tucked deep inside our skulls, is the seat of our most primitive emotions, including fear. The more serotonin produced in this area, then, the more anxious people feel in social situations.
This new finding does not entirely challenge past research. Previous scientific studies proved people with social phobia have higher nerve activity in the amygdala — for anxious people, the fear center of the brain is overly sensitive. This new research fleshes out the prior work with its suggestion that a surplus of serotonin may be (at least part of) the underlying reason for this.
Serotonin, then, does not decrease anxiety as previously assumed, it increases it. Further research into the underlying chemical processes of anxiety should help scientists investigate familiar treatments and possibly develop new ones for what amounts to a debilitating condition for some people.
"We may have to rethink how anxiety-reducing drugs, like serotonin reuptake inhibitors (SSRIs), actually exert their beneficial effects in anxiety disordered patients," Furmark said."