Can fluoxetine (Prozac) cause lightheadedness?

From the Guidelines

Yes, fluoxetine (Prozac) can cause lightheadedness as a side effect, as indicated by the general cautions listed in the guidelines for managing Alzheimer's disease, which include dizziness as a typical side effect of SSRIs, such as fluoxetine 1. This selective serotonin reuptake inhibitor (SSRI) commonly produces this sensation, especially when first starting the medication or after increasing the dose. Lightheadedness typically occurs because Prozac affects serotonin levels in the brain, which can temporarily impact blood pressure regulation and balance mechanisms. Most people find this side effect diminishes within a few weeks as their body adjusts to the medication. Some key points to consider when taking Prozac include:

• Initial dosage: 10 mg every other morning, with a maximum dosage of 20 mg every morning 1
• Side effects may not manifest for a few weeks due to the very long half-life of fluoxetine 1
• Common side effects of SSRIs, including fluoxetine, also include sweating, tremors, nervousness, insomnia or somnolence, and various gastrointestinal and sexual disturbances 1 If you experience persistent or severe lightheadedness while taking Prozac, you should contact your healthcare provider, as they may recommend taking the medication at a different time of day, adjusting the dose, or ensuring you're staying properly hydrated. It's particularly important to rise slowly from sitting or lying positions to minimize this sensation. Never stop taking Prozac suddenly without medical supervision, as this can cause withdrawal symptoms including more severe lightheadedness or dizziness. Additionally, other studies have reported similar side effects, including dizziness, associated with second-generation antidepressants, such as fluoxetine 1.

From the FDA Drug Label

Among 633 adult patients who overdosed on fluoxetine hydrochloride alone, 34 resulted in a fatal outcome, 378 completely recovered, and 15 patients experienced sequelae after overdosage, including abnormal accommodation, abnormal gait, confusion, unresponsiveness, nervousness, pulmonary dysfunction, vertigo, tremor, elevated blood pressure, impotence, movement disorder, and hypomania The most common signs and symptoms associated with non–fatal overdosage were seizures, somnolence, nausea, tachycardia, and vomiting. In patients with diabetes, Prozac may alter glycemic control Hypoglycemia has occurred during therapy with Prozac, and hyperglycemia has developed following discontinuation of the drug. Interference with Cognitive and Motor Performance — Any psychoactive drug may impair judgment, thinking, or motor skills, and patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that the drug treatment does not affect them adversely Discontinuation of Treatment with Prozac — During marketing of Prozac and other SSRIs and SNRIs (serotonin and norepinephrine reuptake inhibitors), there have been spontaneous reports of adverse events occurring upon discontinuation of these drugs, particularly when abrupt, including the following: dysphoric mood, irritability, agitation, dizziness, sensory disturbances (e.g., paresthesias such as electric shock sensations), anxiety, confusion, headache, lethargy, emotional lability, insomnia, and hypomania. Panic disorder (DSM–IV) is characterized by recurrent, unexpected panic attacks, i.e., a discrete period of intense fear or discomfort in which 4 or more of the following symptoms develop abruptly and reach a peak within 10 minutes: ... 8) feeling dizzy, unsteady, lightheaded, or faint;

Yes, fluoxetine (Prozac) can cause lightheadedness, as it is listed as one of the symptoms of panic disorder that the drug is used to treat, and it is also reported as a symptom that may occur upon discontinuation of the drug 2, 2.

From the Research

Fluoxetine and Lightheadedness

• The study published in 1997 3 compared the electrocardiographic effects of fluoxetine and doxepin in patients with major depressive disorder. It found that patients taking doxepin volunteered more side effects, including dizziness/lightheadedness, compared to those taking fluoxetine.
• Although the study does not directly state that fluoxetine causes lightheadedness, it implies that doxepin is more likely to cause this side effect.
• In the study published in 1993 4, patients who were unable to increase the dose of fluoxetine to 20 mg/day were often those with panic disorder, and some of these patients discontinued the drug due to intolerance. However, the specific side effects causing intolerance were not specified.
• The other studies 5, 6, 7 do not mention lightheadedness as a side effect of fluoxetine.

Side Effects of Fluoxetine

• The study published in 1999 7 lists common side effects of SSRIs, including fluoxetine, such as gastrointestinal disturbances, headache, sedation, insomnia, activation, weight gain, impaired memory, excessive persperation, paresthesia, and sexual dysfunction.
• However, lightheadedness is not explicitly mentioned as a common side effect of fluoxetine in this study.
• The study published in 1990 5 reports that 16.2% of patients who ingested fluoxetine alone experienced sleepiness, and 8.1% had a diastolic pressure over 100 mm Hg, but it does not mention lightheadedness.
• The study published in 1996 6 discusses the pharmacokinetic-pharmacodynamic relationship of SSRIs, including fluoxetine, but does not mention lightheadedness as a side effect.