The Drug Fluoxetine Side Effects

Fluoxetine is a prescription medication that treats depression and other psychological disorders. It has been taken with positive results by many people. However, like any drug, fluoxetine has side effects. Most of the side effects are minor, but in very rare instances, severe and even dangerous side effects have occurred.

Sexual Side Effects

Experienced by more than two-thirds of men and women on fluoxetine, decreased interest in sex is by far this medication's most common side effect. In men, fluoxetine can cause impotence, delayed ejaculation or inability to ejaculate. In women, fluoxetine can cause delay or difficulty in reaching orgasm.

Weight Gain

Weight gain is fluoxetine's second most common side effect, affecting about 30 percent of people taking the medication. Though the cause is not fully understood, fluoxetine may affect the regulation of appetite. Gains of up to 20 pounds have occurred.

Less Common Side Effects

Fluoxetine causes rashes, diarrhea, excessive sweating and dry mouth in 4 to 12 percent of users.

Suicidal Thoughts and Behavior

In 2003 the FDA advised that fluoxetine increases the risk of suicide in children and adolescents. The mechanism it triggers is not known, but it is believed that as depressive symptoms lift, patients gain sufficient energy to carry out suicidal thoughts and behaviors. Close monitoring of patients during the early phases of treatment is recommended. Fluoxetine's medication label continues to carry this warning. However, ongoing scientific studies have indicated controversy regarding the extent of this side effect and suggest that fluoxetine is safe for use in adolescents and children, especially when combined with cognitive-behavioral therapy.

Serotonin Syndrome

Serotonin syndrome is a rare but dangerous reaction that can begin within two hours to three days of beginning fluoxetine or increasing the dose taken. The syndrome has multiple mental and physical symptoms, including confusion, anxiety, hallucinations, rigidity, loss of coordination, muscle spasms or rigidity, fever, sweating and changes in blood pressure. Although this reaction is a medical emergency, the symptoms resolve once fluoxetine is stopped.

Low Salt Levels

Fluoxetine has been known to cause low salt levels in the blood. The known cases have occurred in elderly patients taking medications that cause increased excretion of salt in the urine.

Neurological

Fluoxetine's neurological side effects are very rare: 0.1 percent of patients have experienced prolonged muscle contractions and uncontrollable movement of the body, mouth and tongue.

Increased Bleeding

Fluoxetine can decrease the blood's ability to form clots. While this side effect is rare, it is a concern for anyone with a blood disorder or anyone taking a medication, such as warfarin, that affects bleeding time.