From the Guidelines
Fluoxetine can cause frequent urination as a side effect in some people, and if this symptom significantly affects quality of life, consideration should be given to adjusting the dosage or switching to another antidepressant, as evidenced by the most recent study 1. This happens because fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that affects not only brain chemistry but also other body systems. Serotonin receptors are present in the bladder and urinary tract, and when fluoxetine alters serotonin levels, it can affect bladder function, potentially leading to increased urination frequency. Some key points to consider when managing fluoxetine-induced frequent urination include:
- Staying hydrated but reducing fluid intake before bedtime to minimize nighttime urination
- Not stopping fluoxetine suddenly, as this can cause withdrawal symptoms
- Consulting a healthcare provider about symptoms, who may adjust the dosage, suggest taking the medication at a different time of day, or consider switching to another antidepressant
- Being aware that most urinary side effects are mild and may improve as the body adjusts to the medication, typically within a few weeks of starting treatment, as noted in 1. It's also important to note that while the provided studies 1, 1, and 1 discuss various aspects of SSRI use, including side effects and management strategies, the most recent and highest quality study 1 provides the most relevant guidance on managing fluoxetine-induced frequent urination.
From the FDA Drug Label
The overall profile of adverse events was generally similar to that seen in adult studies, as shown in Tables 2 and 3 However, 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
- Urinary frequency is listed as an adverse event associated with fluoxetine use, occurring at an incidence of at least 2% and greater than placebo 2.
- This suggests that frequent urination may be a potential side effect of fluoxetine.
From the Research
Frequent Urination and Fluoxetine
- Frequent urination is not listed as a common side effect of fluoxetine in the study 3.
- However, studies have shown that selective serotonin reuptake inhibitors (SSRIs), including fluoxetine, can cause urinary incontinence in some patients 4, 5.
- The study 5 found that SSRI use was associated with an increased risk of developing urinary incontinence, with an incidence density ratio of 1.75 (95% CI 1.56-1.97).
- Another study 4 reported cases of urinary incontinence in patients taking SSRIs, including paroxetine and sertraline, but not fluoxetine specifically.
- The study 6 lists side effects of SSRIs, including gastrointestinal disturbances, headache, sedation, insomnia, activation, weight gain, impaired memory, excessive perspiration, paresthesia, and sexual dysfunction, but does not mention frequent urination or urinary incontinence.
- The pharmacokinetics of fluoxetine, including its half-life and active metabolite, are discussed in the study 7, but do not provide information on the risk of frequent urination.