Citalopram, sold under the brand name Celexa among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class.

[5][6] Common side effects include nausea, trouble sleeping, sexual problems, shakiness, feeling tired, and sweating.

[7] Serious side effects include an increased risk of suicide in those under the age of 25, serotonin syndrome, glaucoma, and QT prolongation.

[30] A meta-analysis, including studies with fluoxetine, paroxetine, sertraline, escitalopram, and citalopram versus placebo, showed SSRIs to be effective in reducing symptoms of premenstrual syndrome, whether taken continuously or just in the luteal phase.

[35] Some research suggests citalopram interacts with cannabinoid protein-couplings in the rat brain, and this is put forward as a potential cause of some of the drug's antidepressant effects.

[38] Citalopram theoretically causes side effects by increasing the concentration of serotonin in other parts of the body (e.g., the intestines).

[34]: 104 Other common side effects of citalopram include drowsiness, insomnia, nausea, weight changes (usually weight gain), increase in appetite, vivid dreaming, frequent urination, dry mouth,[37] increased sweating, trembling, diarrhea, excessive yawning, severe tinnitus, and fatigue.

Less common side effects include bruxism, vomiting, cardiac arrhythmia, blood pressure changes, dilated pupils, anxiety, mood swings, headache, hyperactivity and dizziness.

[34]: 105 According to an article published in 2020, one of the other rare side effects of Citalopram could be triggering visual snow syndrome; which does not resolve after the discontinuation of the medicine.

[44] Other symptoms may be genital anesthesia, anhedonia, decreased libido, vaginal lubrication issues, and nipple insensitivity in women.

[46] A further clarification, issued in March 2012, restricted the maximum dose to 20 mg for subgroups of patients, including those older than 60 years and those taking an inhibitor of cytochrome P450 2C19.7.

[48] Citalopram has no significant effect on insulin sensitivity in women of reproductive age[49] and no changes in glycaemic control were seen in another trial.

[51] It is uncertain whether there is an increased prevalence of septal heart defects among children whose mothers were prescribed an SSRI in early pregnancy.

[52][53] Overdosage may result in vomiting, sedation, disturbances in heart rhythm, dizziness, sweating, nausea, tremors, and rarely amnesia, confusion, coma, or convulsions.

Citalopram and N-desmethylcitalopram may be quantified in blood or plasma to confirm a diagnosis of poisoning in hospitalized patients or to assist in a medicolegal death investigation.

[58] Withdrawal symptoms can occur when this medicine is suddenly stopped, such as paraesthesiae, sleeping problems (difficulty sleeping and intense dreams), feeling dizzy, agitated or anxious, nausea, vomiting, tremors, confusion, sweating, headache, diarrhea, palpitations, changes in emotions, irritability, and eye or eyesight problems.

[59] Citalopram should not be taken with St John's wort, tryptophan or 5-HTP as the resulting drug interaction could lead to serotonin syndrome.

[60] With St John's wort, this may be caused by compounds in the plant extract reducing the efficacy of the hepatic cytochrome P450 enzymes that process citalopram.

[citation needed] Citalopram is contraindicated in individuals taking MAOIs, owing to a potential for serotonin syndrome.

SSRIs, including citalopram, can increase the risk of bleeding, especially when coupled with aspirin, NSAIDs, warfarin, or other anticoagulants.

Distinct from some other agents in its class, it exhibits linear pharmacokinetics and minimal drug interaction potential, making it a better choice for the elderly or comorbid patients.

[68] 1211 Citalopram was first synthesized in 1972 by chemist Klaus Bøgesø[73] and his research group at the pharmaceutical company Lundbeck and was first marketed in 1989 in Denmark.