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Selective Serotonin Reuptake Inhibitors

SSRI Medications, SSRI Drugs


About Selective serotonin reuptake inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are a form of antidepressant medication that first became available in 1987. Today, these drugs are widely used as a first-choice treatment for depression. They are as effective as medications such as tricyclic antidepressants, yet often have far fewer side effects. SSRIs are available by prescription in pill form.

Scientists do not know precisely how SSRIs work, although they appear to prevent certain nerve cells in the brain from reabsorbing the neurotransmitter serotonin. This leaves more serotonin available in the body, which appears to improve mood. The word “selective” is used to describe these medications because they appear to affect only serotonin while leaving other neurotransmitters alone. The blocking action of SSRIs works fairly quickly in the body but the antidepressant effects of the drug may not appear for three to six weeks after the beginning of treatment.

SSRIs are often safer than many other kinds of antidepressants, most notably the tricyclics and the MAO inhibitors. They also are less dangerous if accidentally taken at overdose levels. Finally, they are less likely to trigger seizures or heart problems.

In research studies, SSRIs have been associated with an increased risk of suicidal thoughts and behaviors in children and adolescents. Because of this risk, in 2005 the U.S. Food and Drug Administration (FDA) adopted a ‘black box warning’ for all SSRIs. The warning alerts patients and physicians of the potential for the drug to increase suicidal thoughts in this population. It also recommends close monitoring of any individuals using SSRIs for worsening depression or unusual behaviors. Additional research is continuing to more clearly understand the association between SSRIs and suicide risk.

All antidepressants are normally prescribed for at least six months to evaluate their effectiveness and to prevent risk of relapse. Patients should not stop taking antidepressants unless they do so in close consultation with their physician.

SSRIs tend to have varying half-lives. A half-life is the length of time it takes for the amount of drug in the blood to drop by 50 percent. The half life is used to calculate the medication dosage, and it can affect the transition from using SSRIs to another kind of antidepressant.


Types and differences of SSRIs

There are several different types of selective serotonin reuptake inhibitors (SSRIs) available to treat depression. Some of these drugs are available in extended-release or controlled-release formulations (designated by an “XR” or “CR” at the end of the medication name). These types of SSRIs are slowly released in the body via a single dose over the course of a day or week.

The various SSRIs are structurally distinct. Therefore, a lack of response to one SSRI does not mean that another will also be unsuccessful. Patients may also be allergic to one SSRI, but not others. Common SSRIs include:

Generic NameBrand Name(s)














Conditions treated

Patients who are depressed, anxious or irritable are often good candidates for selective serotonin reuptake inhibitors (SSRIs). Children with depression also tend to respond well to SSRIs, although only one (fluoxetine) has been approved for use in children. These medications may be used to treat a number of mental health disorders, such as:

  • Mood disorders (e.g., dysthymia, major depression)
  • Anxiety disorders (e.g., obsessive-compulsive disorder, post-traumatic stress disorder, social phobia)
  • Borderline personality disorder (BPD)
  • Autism
  • Eating disorders (e.g., bulimia nervosa, anorexia nervosa)
  • Premenstrual dysphoric disorder

Conditions of concern

Patients should alert their physician about any other prescription or over-the-counter medications or supplements they are taking prior to beginning selective serotonin reuptake inhibitor (SSRI) therapy. They should also report any personal and family history of the following health conditions:

  • depression, bipolar disorder or mania
  • Suicide attempts
  • Heart disease and heart attacks
  • Diabetes
  • Seizures
  • Liver or kidney disease
Side effects

Potential side effects of SSRIs

Patients should be aware that a physician may need to adjust the dosage or change medications to achieve the best results with minimal side effects. In addition, the U.S. Food and Drug Administration (FDA) has advised that antidepressants may increase the risk of suicidal thinking in some patients. In 2005, a “black box warning” was added to all SSRIs indicating these increased risks. The warning also recommends that people being treated with SSRIs should be monitored closely for unusual changes in behavior and worsening of depression.

Selective serotonin reuptake inhibitors (SSRIs) tend to be safer and tolerated better than some other antidepressants, but do occasionally cause unwanted effects. These side effects tend to be a result of the increased serotonin activity. It is not unusual for patients to experience tension headaches during the early part of treatment. These are typically managed with over-the-counter medications. Other side effects include:

  • Nausea and gastrointestinal upset. May be reduced by taking the medication with a meal, or by taking an extended-release SSRI.
  • Anxiety. May be lessened by avoiding caffeine and oral decongestants.
  • Insomnia. May be alleviated by taking the medication in the morning or taking a sedative at night.
  • Restlessness. May be lessened by getting regular exercise and avoiding caffeine-containing substances (e.g., coffee).

Many of the side effects generally diminish over time. Some patients who take SSRIs may notice additional side effects after several months of usage. These include loss of energy, passivity and decreased pleasure. The condition may appear similar to depression, but without the pervasive sadness. In such cases, the patient may be prescribed a different antidepressant.

Sexual dysfunction is also a common side effect of SSRI use. Both genders may experience decreased libido (sex drive). In addition, women may experience an inability to orgasm and men may have delayed or absent ejaculation. Because these side effects are usually only associated with SSRI use, patients experiencing sexual dysfunction may be able to switch to a non-SSRI antidepressant.

Patients who abruptly stop taking SSRIs can experience withdrawal symptoms. This is sometimes called “discontinuation syndrome” and may be characterized by nausea, dizziness, headache, lethargy and flu-like symptoms. For this reason, patients should consult a physician before stopping use of SSRIs.


Drug or other interactions

Patients should consult their physician before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.

Combining selective serotonin reuptake inhibitors (SSRIs) with monoamine oxidase inhibitors (MAOIs) and other medications and supplements (e.g., St. John’s wort) can lead to serotonin syndrome. This is a condition that results in a potentially fatal buildup of serotonin in the brain. It is marked by fever, confusion, fluctuations in heart rhythms and blood pressure, increased perspiration, muscle rigidity, seizures and problems with the liver or kidneys. In severe cases, coma and death can result.

In addition, SSRIs can also potentially affect the metabolism of a number of other drugs leading to serious problems.

How to use

Pregnancy use issues

The safety of antidepressant use in pregnancy is not completely understood. Therefore, women who are pregnant or who are thinking of becoming pregnant and those who are breastfeeding should consult their physician before using selective serotonin reuptake inhibitors (SSRIs). In addition, some SSRIs have been found to pass into breast milk, although the effect on nursing children is unknown. Research has shown that the SSRI paroxetine is especially likely to be associated with birth defects indicating that it should be avoided in pregnant women or those who may become pregnant during treatment with this medication.

Child use issues

The selective serotonin reuptake inhibitor (SSRIs) fluoxetine is the only antidepressant that has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of depression in children. Other antidepressants, including SSRIs, are prescribed by physicians for children in some cases.

Studies have shown that the use of antidepressants may cause some children and adolescents to exhibit unusual behavior and have increased suicidal thoughts and feelings. For this reason, antidepressants should be used with caution in children. All children and individuals should be closely monitored by their physicians as indicated on the FDA’s “black box warning” on all SSRIs.

Elderly use issues

Elderly patients may be more likely to experience side effects associated withantidepressants such as selective serotonin reuptake inhibitors (SSRIs). To reduce the risk of such side effects, lower dosage levels are often necessary in treating elderly patients.

Symptoms of medication overdose

Symptoms of selective serotonin reuptake inhibitor (SSRI) overdose are generally less severe than those of other antidepressants. The following symptoms warrant immediate medical attention:

  • Unsteadiness
  • Confusion
  • Unresponsiveness
  • Nervousness
  • Dizziness or fainting
  • Rapid, irregular or pounding heartbeat
  • Hallucinations
  • Fever
  • Hair loss
  • Gastrointestinal problems, such as vomiting and diarrhea

Questions for your doctor

Patients may wish to ask their doctor the following questions about selective serotonin reuptake inhibitors (SSRIs):
  1. Am I candidate for any SSRI medication?
  2. Why are SSRIs a better choice for me than other antidepressants?
  3. Which of the various SSRIs is best for my condition?
  4. What are the risks and side effects associated with this drug?
  5. How quickly can I expect to see an improvement in my condition?
  6. If one SSRI doesn’t work for me, will you recommend a different type?
  7. Which drugs should I avoid while taking an SSRI?
  8. Is it okay for me to drink alcohol while taking an SSRI?
  9. What side effects indicate the need for immediate medical attention?
  10. What are the symptoms of withdrawal from this drug?
  11. Are SSRIs safe for my child to use for depression?

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