Adverse Effects and Treatment Satisfaction Among Online Users of Four Antidepressants

Background: An estimated 13% of American adults currently take an antidepressant medication, double the number of adult users compared to the turn of the century. While about a dozen SSRI and SNRI antidepressant brands exist on the market and new multi-modal antidepressants have more recently been released, clinical trial research demonstrates generally comparable efficacy and adverse effect (AE) profiles across most of these drugs. Common AEs associated with antidepressant treatment according to clinical studies are nausea, vomiting, diarrhea, dry mouth, sweating, headache, dizziness, anxiety, tremor, insomnia, sexual dysfunction, and weight gain. Surveys utilizing self-report have found high rates of emotional and interpersonal AEs, including feeling emotionally numb, feeling "not like myself," reduced positive feelings, and caring less about others. However, these emotional AEs and the phenomenon of SSRI-induced indifference have received scant attention in clinical studies and are not commonly listed in the literature as part of antidepressants’ known or expected AE profiles. In this context, first-hand accounts of antidepressant users on the Internet can supplement AE profiles with information gained from real-world treatment experiences.

Method: We examined online user reviews of two older (escitalopram, duloxetine) and two newer (vilazodone, vortioxetine) antidepressants for differences in their AE profiles and determined which categories of AEs were associated with users’ satisfaction. A codebook of 60 physical, emotional, and behavioral AEs was used for line-by-line coding of effects reported among 3,243 user reviews from three popular health websites.

Results: Psychiatric effects were commonly reported (41%), followed by sleep (31.9%) and gastrointestinal (25.0%) effects. Specific AEs statistically significantly varied across drugs, creating potentially meaningful differences in AE profiles. Users of newer drugs more often reported emotional instability, while users of older drugs reported more emotional blunting. Psychiatric AEs demonstrated moderate to substantial relationships with users’ satisfaction, whereas gastrointestinal, metabolic, or sexual AEs were minimally related.

Discussion: The findings of this study suggest that psychiatric AEs may play a more prominent role in users’ evaluation of an antidepressant drug experience than what might be inferred from results reported in clinical drug studies. While broadly congruent with antidepressant AE profiles summarized in the published literature, online user reviews highlight the impact of psychiatric AEs, which demonstrated moderate to substantial relationships to overall satisfaction. Over 41% of 3,243 antidepressant users reported a psychiatric AE, and this category of AEs had a stronger relationship with satisfaction relative to AEs reported within any other MedDRA system organ class.

The findings of this study suggest that psychiatric AEs may play a more prominent role in users’ evaluation of an antidepressant drug experience than what might be inferred from results reported in clinical drug studies. While broadly congruent with antidepressant AE profiles summarized in the published literature, online user reviews highlight the impact of psychiatric AEs, which demonstrated moderate to substantial relationships to overall satisfaction. More specific and systematic assessment of a broader range of AEs is needed in both research and practice.