Selective Serotonin Reuptake Inhibitors (SSRIs)

Medications Commonly Used for Panic Disorder Treatment

Selective serotonin reuptake inhibitors (SSRIs) are a fairly new class of antidepressants. In 1987, Prozac (fluoxetine), manufactured by Ely Lilly Company, was the first SSRI to enter the U.S. market as an approved treatment for depression. Since then, numerous other SSRIs have emerged and their proven effectiveness have gone beyond the treatment of depression. SSRIs have been useful in treating many anxiety-related illnesses including panic disorder (PD) and are usually the first choice of medication intervention prescribed for PD treatment.

How SSRIs Work

It is believed that the brain contains several hundred different types of chemical messengers (neurotransmitters) that act as communication agents between different brain cells. Serotonin is a neurotransmitter that is important in modulating a variety of body functions and feelings, including our mood. Low serotonin levels have been linked to depression and anxiety. As the name implies, SSRIs inhibit the reuptake of serotonin in the brain. This causes an increase of serotonin in an area of the brain called the synaptic cleft, which is a small space between brain cells.

SSRIs Commonly Prescribed to Treat Panic Disorder

After an evaluation by your doctor, he or she will determine which SSRI would be best for you. Commonly prescribed SSRIs for panic disorder include:

  • Fluoxetine (Prozac, Prozac Weekly)
  • Citalopram (Celexa)
  • Escitalopram (Lexapro)
  • Paroxetine (Paxil, Paxil CR)
  • Sertraline (Zoloft)

    Prozac Weekly is an extended-release medication that works by taking a single dose that processes in the body over a 7-day period. Paxil CR is a controlled- release form that releases medication at intervals throughout the day. With the exception of Prozac Weekly, SSRIs are usually taken on a daily basis.

    Side Effects of SSRIs

    One of the attractions of SSRIs is that they are believed to be safer and produce fewer unwanted side effects than other classes of antidepressants. But any medication can cause some side effect complications, especially during the beginning of treatment.

    Some common side effects of SSRIs include:

    • Nausea
    • Sexual dysfunction, including reduced desire or orgasm difficulties
    • Headache
    • Stomach upset
    • Nervousness
    • Weight gain
    • Drowsiness
    • Insomnia

    Some of these side effects will be eliminated after your body adjusts to the medication. If they don’t and are bothersome, your doctor may try another SSRI. Although SSRIs function by a similar mode of action, they are different. Certain side effects with one SSRI may not be a problem with another.

    Serotonin Syndrome

    Dangerously high levels of serotonin in the brain can cause a potentially life-threatening condition called serotonin syndrome. This rare condition is usually the result of an interaction of two or more drugs that affect brain serotonin levels.

    Particularly troublesome is mixing SSRIs with a class of antidepressants called monoamine oxidase inhibitors (MAOIs). MAOIs should not be taken with SSRIs, and SSRI therapy should not begin for two to four weeks after discontinuation of an MAOI, due to the increased risk of serotonin syndrome. Even some over-the-counter supplements, such as the herb, St. John’s Wort, can result in serotonin syndrome if mixed with SSRIs.

    Signs and symptoms of serotonin syndrome include:

    • Confusion
    • Restlessness
    • Hallucinations
    • Extreme agitation
    • Fluctuations in blood pressure
    • Heart palpitations
    • Nausea
    • Fever
    • Seizures
    • Coma

    To avoid possible drug interactions, make sure all of your treating doctors know you are taking an SSRI. Before taking any over-the-counter medications or dietary supplements while you are on an SSRI, check with your doctor.

    SSRIs and Pregnancy

    Recent studies have linked Paxil to an increased risk of birth defects, particularly heart defects, when taken during the first trimester of pregnancy. Some of these defects are mild and resolve without intervention, but some may be quite serious. It has also been suggested that exposure to SSRIs during late pregnancy may increase the risk of persistent pulmonary hypertension, a serious lung disorder, in a newborn.

    If you are nursing or are pregnant, it is best to discuss the risks and benefits of SSRI therapy with your doctor.

    SSRI Discontinuation Syndrome

    Some people have reported withdrawal-like symptoms when decreasing or stopping SSRI therapy. It is believed that these symptoms are a result of the brain trying to stabilize serotonin levels after an abrupt change.

    Symptoms that may occur during discontinuation of SSRI therapy include:

    • Nausea
    • Headache
    • Muscle Aches
    • Dizziness
    • Electric shock-like sensations in the neck and head

    While all of these symptoms are not believed to be dangerous, they can be quite disconcerting. When discontinuing an SSRI, your doctor may give you a gradual reduction schedule to avoid these withdrawal-like symptoms.

    SSRIs and Suicide

    The association of increased suicidal thoughts, especially among adolescents, with SSRI treatment has been a center of attention and controversy in recent years. In response to the concerns suggested in case studies and some research, the U.S. Food and Drug Administration (FDA) issued a statement in 2007. The FDA proposed that makers of all antidepressant medications indicate a warning on their products about a possible increased risk of suicidal thinking and behavior in young adults, ages 18 to 24, during initial treatment.

    So far, researchers have not found a definitive answer about the SSRI-suicide connection. For the vast majority of people, SSRIs decrease depression and alleviate the helplessness and hopelessness that consumes their daily existence. But, for a very small percentage of people taking SSRIs, this may not be the case. If you are concerned about this issue, be open with your doctor and don’t be afraid to ask questions.


    Antidepressant Use in Children, Adolescents, and Adults. Revisions to Product Labeling. U.S. Food and Drug Administration. May 2, 2007.

    Kaplan, H.I. and Sadock, B.J. Synopsis of Psychiatry, Eighth Edition. Baltimore: Williams & Wilkins. 1998.

    Continue Reading