Most Common Side Effects of SSRIs
The most common side effects of SSRIs are gastrointestinal symptoms (particularly nausea, diarrhea, and dry mouth), headache, and sexual dysfunction, with nausea being the most frequent reason for treatment discontinuation. 1
Gastrointestinal Effects (Most Prevalent)
- Nausea and vomiting are the most commonly reported adverse effects and the leading cause of SSRI discontinuation in clinical practice. 1
- Diarrhea occurs frequently, with sertraline showing higher rates than other SSRIs including bupropion, citalopram, fluoxetine, fluvoxamine, mirtazapine, nefazodone, paroxetine, and venlafaxine. 1
- Dry mouth, heartburn, and constipation are also common gastrointestinal complaints during SSRI treatment. 1
- These gastrointestinal effects typically emerge within the first few weeks of treatment. 1
Neurological and Psychiatric Effects
- Headache is among the most frequently reported side effects across all SSRIs, occurring in up to 17 per 1,000 person-months of therapy. 1, 2
- Dizziness, somnolence, and insomnia are common neurological complaints. 1
- Tremor and nervousness occur regularly during SSRI treatment. 1
- Fatigue and vivid dreams are additional neuropsychiatric effects reported by patients. 1
Sexual Dysfunction (Highly Prevalent but Often Underreported)
- Sexual dysfunction is extremely common with SSRIs, though absolute rates are likely underreported in clinical trials. 1, 3
- The most common sexual side effects include delayed ejaculation, erectile dysfunction, and anorgasmia (absent or delayed orgasm). 1, 3
- Paroxetine demonstrates significantly higher rates of sexual dysfunction compared to fluoxetine, fluvoxamine, nefazodone, and sertraline. 1
- Bupropion has a significantly lower rate of sexual adverse events than fluoxetine or sertraline. 1
- Sexual dysfunction appears strongly dose-related and varies among SSRIs based on serotonin and dopamine reuptake mechanisms. 3
Other Common Side Effects
- Increased sweating (diaphoresis) is frequently reported across all SSRIs. 1
- Changes in appetite and weight (either gain or loss) occur commonly, with mirtazapine and paroxetine causing higher weight gain than sertraline, trazodone, or venlafaxine. 1
- Bruxism (teeth grinding) is a recognized side effect of SSRI treatment. 1
Important Clinical Considerations
- Approximately 63% of patients receiving SSRIs experience at least one adverse effect during treatment. 1
- Most adverse effects emerge within the first few weeks of treatment initiation. 1
- Starting at lower doses and slowly titrating upward can minimize initial side effects, particularly gastrointestinal symptoms and behavioral activation. 1, 4
- The American Academy of Child and Adolescent Psychiatry recommends slow up-titration to avoid unintentionally exceeding the optimal medication dose and to reduce early adverse effects. 1
Common Pitfall to Avoid
Do not dismiss patient reports of sexual dysfunction as these effects are significantly underreported in clinical trials and can severely impact medication adherence and quality of life. 1, 3 Proactively ask about sexual side effects at follow-up visits, as patients often do not volunteer this information.