SSRI is an abbreviation for class of drugs known as selective serotonin reuptake inhibitors. This class of drugs was originally developed as antidepressants. The first drug in this class that was released in the United States was Prozac (fluoxetine). Many others have followed. Other examples include Celexa (citalopram), Lexapro (escitalopram), Paxil (paroxetine), Luvox (fluvoxamine), and Zoloft (sertraline). SSRIs have found a variety of other uses including treatment for anxiety disorders, social anxiety, panic disorders, obsessive-compulsive disorder, eating disorders, posttraumatic stress disorder (PTSD), and chronic pain. Physicians have also found SSRIs useful in certain individuals suffering with irritable bowel syndrome, lichen simplex chronicus, and premature ejaculation.

SSRIs work by inhibiting the reuptake of serotonin into the presynaptic cell, thereby causing an increase in the level of the neurotransmitter serotonin available to the postsynaptic cell receptors. SSRIs "selectively" affect serotonin, and not other neurotransmitters.

Multiple factors, including genetics, play a part in determining which SSRI will work in a given individual or if that class of drugs will work at all. Also it is important to bear in mind that it may take several weeks for the SSRI that was prescribed to begin to exhibit the desired clinical effect. Changing from one SSRI to another is not uncommon.

As a general class, SSRIs can produce some of the same side effects which may include:

• nausea
• sexual dysfunction
• dry mouth
• headache
• diarrhea
• nervousness
• rash
• agitation
• restlessness
• increased sweating
• weight gain
• drowsiness
• insomnia

Although SSRIs are not considered to be addictive, abrupt discontinuation has been associated with a rebound syndrome that can last from one to several weeks. Double-blind studies have indicated that this phenomenon occurs in 35 – 78% of patients.

Neurologic symptoms may include:

• dizziness
• vertigo
• lightheadedness
• difficulty walking

Somatic (bodily) complaints may include:

• nausea/vomiting
• fatigue
• headache
• insomnia

Less common complaints may include:

• shock-like sensations
• paresthesia (skin crawling, burning, or prickling)
• visual disturbances
• diarrhea
• muscle pain
• chills
• agitation
• impaired concentration
• vivid dreams
• depersonalization (sense of unreality and loss of self)
• irritability
• suicidal thoughts
(http://bipolar.about.com/cs/antidep/a/0207_ssridisc1.htm)

To avoid this, physicians usually recommend tapering off SSRIs slowly unless abrupt discontinuation is indicated for medical reasons.

Another rare but potentially very serious (or even fatal) condition associated with use of SSRIs is called Serotonin Syndrome. It is caused by an excess of serotonin in the central nervous system and peripheral serotonin receptors.

Signs and symptoms of serotonin syndrome can range from mild to severe. They may include:

• Cognitive effects such as mental confusion, hypomania, hallucinations, agitation, headache, or coma
• Autonomic effects like shivering, sweating, hyperthermia (fever), hypertension (high blood pressure), tachycardia (rapid heart rate), nausea, or diarrhea
• Somatic effects may include mild clonus (muscle twitching), hyperreflexia, and tremor

Taking an SSRI combination with certain other drugs or herbs can precipitate serotonin syndrome. (For examples see http://en.wikipedia.org/wiki/Serotonin_syndrome). If serotonin syndrome is suspected, immediate medical attention is indicated. With appropriate medical management, serotonin syndrome is usually associated with a favorable outcome.

http://en.wikipedia.org/wiki/SSRI

http://bipolar.about.com/cs/antidep/a/0207_ssridisc1.htm

http://www.healthyplace.com/depression/antidepressants/list-of-antidepressants/menu-id-68/

http://www.drugs.com