Active Ingredients

Fluoxetine – Effect, Application & Risks


Fluoxetine is a drug from the drug class of antidepressants . The active ingredient belongs to the selective serotonin reuptake inhibitors (SSRI).

What is fluoxetine?

After zimelidine (now no longer approved), fluoxetine is the second drug from the generation of selective serotonin reuptake inhibitors (SSRI). The pharmaceutical company Lilly received the first patent in 1975. It was launched in the USA in 1988 under the name Prozac. In Germany, the drug has been available as Fluctin since 1990.

Selective serotonin reuptake inhibitors such as fluoxetine are used in Germany to treat depression . The drug is also used in the treatment of obsessive-compulsive disorders or bulimia .

One of the most common side effects of the antidepressant is nausea . A fifth of all patients treated with fluoxetine complain of severe nausea. It can also lead to insomnia and severe fatigue .

Pharmacological action

Fluoxetine inhibits the reuptake of serotonin in the synaptic cleft . Serotonin is a neurotransmitter and tissue hormone . The substance is found in the gut nervous system , central nervous system , blood , and cardiovascular system .

Serotonin fulfills various functions in these organ systems. For example, it relaxes the smooth muscles in the blood vessels or stimulates intestinal activity . However, the most well-known effect of serotonin is on mood. Serotonin provides a feeling of serenity, contentment, and inner peace . A lack of serotonin leads to feelings of anxiety , depression, heartache and aggressiveness . Because of this effect, serotonin is popularly known as the happiness hormone .

Depressed and other mentally ill patients often show a pronounced lack of serotonin. Therefore, selective serotonin reuptake inhibitors such as fluoxetine are used. Fluoxetine inhibits the uptake of serotonin from the synaptic cleft. This prolongs the effect of the neurotransmitter that has already been absorbed. Furthermore, fluoxetine shows a direct effect on the serotonin receptors in the central nervous system. At higher doses, fluoxetine can also inhibit norepinephrine reuptake.

Medical Application & Use

The drug fluoxetine is used to treat obsessive-compulsive disorder and depression. The active ingredient is also used as a medicinal supplement in the treatment of eating disorders and self-induced vomiting. By increasing the serotonin content in the brain , fluoxetine increases the drive in those affected.

Risks & side effects

The drug fluoxetine must not be used in children under the age of eight. It can be used to treat major depressive disorder in children over the age of eight and in adolescents. It should be noted that fluoxetine can lead to suicidal behavior, especially in younger people. This results from the fact that some depressed patients, through the energy gained from the antidepressants, now put suicidal thoughts that they had only imagined into practice. Before, they didn’t have the energy to do it.

Fluoxetine must not be used in acute manic states. Patients with mania suffer from an abnormally elevated mood, which would further increase with the use of fluoxetine. Furthermore, the drug must not be taken together with MAO inhibitors. MAO inhibitors are used to treat depression and Parkinson’s disease . Severe to fatal side effects can occur in combination with fluoxetine. After stopping fluoxetine, patients must wait at least five weeks before they can take an MAOI. Therefore, switching from fluoxetine to an MAOI or from an MAOI to fluoxetine should only be done under the supervision of a doctor.

Nausea is one of the most common side effects of the drug. More than 20 percent of all patients taking fluoxetine suffer from nausea. Insomnia is also a common side effect. Other side effects include fatigue and loss of appetite . Anxiety, nervousness , muscle weakness, and muscle tremors are also potential side effects. In particular, states of anxiety, mania, nervousness and sleep disorders lead to patients stopping treatment with fluoxetine.

Another common side effect of selective serotonin reuptake inhibitors like fluoxetine is libido dysfunction . Other sexual dysfunctions, such as the inability to have an orgasm, can also be side effects of SSRIs.

Some patients develop hives and sometimes severe skin rashes while taking the antidepressant . About a third of patients with these skin symptoms discontinue therapy with fluoxetine.

The phenomenon of akathisia (restlessness when sitting) is also a frequent side effect. With akathisia, patients cannot remain still in one position. You are very restless. Akathisia usually occurs immediately after the start of therapy or when the dose is increased. It disappears when treatment is stopped or the dose is reduced.

When fluoxetine is combined with drugs that also affect the serotonin system, a condition called serotonin syndrome can develop. It is a complex of symptoms caused by the accumulation of serotonin in parts of the body. Symptoms of serotonin syndrome include sweating , tremors , and chills . The syndrome can sometimes be fatal. Particular care should be taken when combining fluoxetine with MAO inhibitors, tramadol , triptans, lithium , St. John’s wort and tryptophan . When combining fluoxetine with substances such as carbamazepine ,Haloperidol or tricyclic antidepressants may develop blood level shifts and toxicities.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.