From the Guidelines
Prozac (fluoxetine) commonly causes side effects including nausea, headache, insomnia, drowsiness, diarrhea, and sexual adverse events, as reported in a clinical practice guideline from the American College of Physicians 1. These side effects are often mild to moderate and may improve after the first few weeks of treatment as the body adjusts to the medication. Some of the most commonly reported adverse events associated with Prozac include:
- Nausea and vomiting, which are also the most common reasons for discontinuation in efficacy studies
- Diarrhea, with sertraline having a higher rate of diarrhea than other SSRIs like fluoxetine
- Headache
- Insomnia
- Dizziness
- Sexual adverse events, with paroxetine having higher rates of sexual dysfunction than fluoxetine It's essential to note that some patients may experience more severe side effects, such as unusual agitation, significant weight changes, or suicidal thoughts, particularly when first starting the medication or after dose adjustments. If side effects become bothersome, it's crucial not to stop taking Prozac abruptly, as this can cause withdrawal symptoms. Instead, patients should consult their healthcare provider, who may adjust the dosage or recommend taking the medication at a different time of day to help manage side effects, as suggested by the guideline from the American College of Physicians 1.
From the FDA Drug Label
In US placebo–controlled clinical trials for major depressive disorder, 12% to 16% of patients treated with Prozac and 7% to 9% of patients treated with placebo reported anxiety, nervousness, or insomnia. In US placebo–controlled clinical trials for OCD, insomnia was reported in 28% of patients treated with Prozac and in 22% of patients treated with placebo Anxiety was reported in 14% of patients treated with Prozac and in 7% of patients treated with placebo. In US placebo–controlled clinical trials for bulimia nervosa, insomnia was reported in 33% of patients treated with Prozac 60 mg, and 13% of patients treated with placebo Anxiety and nervousness were reported, respectively, in 15% and 11% of patients treated with Prozac 60 mg and in 9% and 5% of patients treated with placebo Among the most common adverse events associated with discontinuation (incidence at least twice that for placebo and at least 1% for Prozac in clinical trials collecting only a primary event associated with discontinuation) in US placebo–controlled fluoxetine clinical trials were anxiety (2% in OCD), insomnia (1% in combined indications and 2% in bulimia), and nervousness (1% in major depressive disorder) In addition, the following adverse events (excluding those which appear in the body or footnotes of Tables 2 and 3 and those for which the COSTART terms were uninformative or misleading) were reported at an incidence of at least 2% for fluoxetine and greater than placebo: thirst, hyperkinesia, agitation, personality disorder, epistaxis, urinary frequency, and menorrhagia The most common adverse event (incidence at least 1% for fluoxetine and greater than placebo) associated with discontinuation in 3 pediatric placebo–controlled trials (N=418 randomized; 228 fluoxetine–treated; 190 placebo–treated) was mania/hypomania (1. 8% for fluoxetine–treated, 0% for placebo–treated). In a placebo–controlled clinical trial, more patients taking Prozac Weekly reported diarrhea than patients taking placebo (10% versus 3%, respectively) or taking Prozac 20 mg daily (10% versus 5%, respectively).
Common side effects of Prozac include:
- Anxiety
- Insomnia
- Nervousness
- Anorexia (decreased appetite)
- Weight loss
- Diarrhea
- Thirst
- Hyperkinesia
- Agitation
- Personality disorder
- Epistaxis
- Urinary frequency
- Menorrhagia These side effects were reported in US placebo-controlled clinical trials for major depressive disorder, OCD, bulimia nervosa, and panic disorder 2, 2.
From the Research
Common Side Effects of Prozac
- Decreased libido: reported in studies as a common side effect of Prozac, with a significant increase in incidence when physicians asked patients direct questions 3, 4
- Delayed orgasm or anorgasmia: found to be more prevalent with paroxetine than with fluoxetine, fluvoxamine, and sertraline 3
- Delayed ejaculation: more common with paroxetine than with fluoxetine, fluvoxamine, and sertraline 3
- Impotence: reported as a side effect of Prozac, with paroxetine provoking more impotence than fluvoxamine, fluoxetine, and sertraline 3
- General sexual satisfaction: decreased in patients taking Prozac, with only 24.5% of patients having a good tolerance of their sexual dysfunction 3
Comparison with Other Antidepressants
- Trazodone: associated with the fewest sexual dysfunctions compared to fluoxetine and sertraline 5
- Sertraline: associated with intermediate impairment in sexual function, lower than fluoxetine but higher than trazodone 5
- Bupropion: reported to have minimal sexual side effects and has been used to treat fluoxetine-induced sexual dysfunction 6, 7
- Mirtazapine: found to have a lower rate of sexual dysfunction compared to SSRIs 4, 7
Prevalence of Sexual Dysfunction
- Overall prevalence of sexual dysfunction: reported as 39% in patients taking antidepressants, with paroxetine being the most common antidepressant associated with sexual dysfunction 4
- Sexual dysfunction in men and women: men showed more incidence of sexual dysfunction than women, but women's sexual dysfunction was more intense than men's 3