SSRI Discontinuation Syndrome - Diagnosis

Diagnosis

Although most SSRIs are widely used and generally considered safe, an abrupt cessation, or rapid tapering of SSRI use may result in a discontinuation syndrome that can mimic serious illness and can be very distressing and intensely uncomfortable. Several pharmacokinetic and pharmacodynamic factors influence the frequency and onset of these symptoms. When allowed to run its course, the syndrome duration is variable (usually one to several weeks) and ranges from mild-moderate intensity in most patients, to extremely distressing in a smaller number of patients who may have side effects for months.

With the lack of a definition based on consensus criteria for the syndrome, a discontinuation panel met in Phoenix, Arizona in 1997 and stated:

"SSRI discontinuation symptoms... may emerge when an SSRI is abruptly discontinued, when doses are missed, and less frequently, during dosage reduction. In addition, the symptoms are not attributable to any other cause and can be reversed when the original agent is reinstituted, or one that is pharmacologically similar is substituted. SSRI discontinuation symptoms, in most cases, may be minimized by slowly tapering antidepressant therapy, but there have been several case reports where symptoms occurred consistently even through repeated attempts to taper therapy. Physical symptoms include problems with balance, gastrointestinal and flu-like symptoms, and sensory and sleep disturbances. Psychological symptoms include anxiety and/or agitation, crying spells, irritability and aggressiveness."

A 2000 study at the Department of Psychiatry at Dalhousie University in Halifax, Nova Scotia constructed diagnostic criteria for SSRI discontinuation syndrome. These criteria are 2 or more of the following symptoms developing within 1 to 7 days of discontinuation or reduction in dosage of an SSRI after at least 1 month's use, when these symptoms cause clinically significant distress or impairment and are not due to a general medical condition or recurrence of a mental disorder: dizziness, light-headedness, vertigo or feeling faint; shock-like sensations or paresthesia; anxiety; diarrhea; fatigue; gait instability; headache; insomnia; irritability; nausea or emesis; tremor; and visual disturbances.

Due to the lack of peer reviewed diagnostic criteria, many physicians, unaware of the potential severity of discontinuation syndrome, do not get informed consent at the time of initial prescription from the patient (though patients in clinical trials do), so this syndrome can be an unexpected barrier to patients attempting to discontinue the drug. In addition, warnings to patients not to stop taking the drug without doctor's approval, while indicated, may lead to a reluctance to discontinue SSRI therapy in patients who need not take the drugs long-term.