Citalopram, one of the most widely prescribed antidepressants worldwide, carries a side-effect profile that ranges from mild and temporary nuisances to rare but serious medical events. The most common complaints during the first few weeks are nausea, drowsiness, and headache, and these tend to fade as the body adjusts. But some effects, particularly sexual dysfunction and weight changes, can persist or even worsen with long-term use, and a handful of risks demand genuine medical vigilance. Understanding which side effects are transient annoyances and which ones warrant a call to your doctor makes a real difference in how well you manage treatment.
The Early Weeks and Common Side Effects
Most people who start citalopram notice something within the first week or two. Nausea is the most frequently reported side effect and tends to be dose-dependent, meaning higher starting doses produce more stomach upset. Drowsiness and headache round out the trio of complaints that show up most often in clinical trials. In one placebo-controlled study, adverse event rates for citalopram across multiple doses were not statistically different from placebo, which speaks to how mild these early effects tend to be for most people.1Wiley Online Library (Human Psychopharmacology: Clinical and Experimental). Citalopram Compared to Dothiepin and Placebo: Effects on Cognitive Function and Psychomotor Performance
A broader review of newer-generation antidepressants noted that several side effects are transient and may disappear after a few weeks. The gastrointestinal symptoms, including nausea, diarrhea, and indigestion, typically fall into this category.2Karger Publishers (Psychotherapy and Psychosomatics). The Safety, Tolerability and Risks Associated with the Use of Newer Generation Antidepressant Drugs: A Critical Review of the Literature Insomnia or aggravated sleep problems can also occur early on; in one trial comparing citalopram to another antidepressant for insomnia and anxiety, some patients in the citalopram group experienced headache and worsened insomnia as adverse reactions.3PubMed Central. Efficacy and safety evaluation of citalopram and doxepin on sleep quality in comorbid insomnia and anxiety disorders The practical takeaway: if you feel lousy during the first couple of weeks, that is a common experience, and most of those symptoms ease on their own. It does not mean the medication will always feel that way.
Sexual Side Effects and the Question of Persistence
Sexual dysfunction is one of the side effects people worry about most, and for good reason. Reduced libido, difficulty reaching orgasm, and erectile dysfunction are all well-documented with SSRIs including citalopram. What makes sexual side effects different from, say, nausea is that they do not reliably go away after the first few weeks. For many people, they persist for the entire duration of treatment.
The more troubling finding is that for some patients, sexual function does not fully return to normal even after stopping the drug. This condition, known as post-SSRI sexual dysfunction (PSSD), is characterized most commonly by genital numbness, weak or pleasureless orgasm, loss of libido, and erectile dysfunction.4PubMed Central. Post-SSRI sexual dysfunction: barriers to quantifying incidence and prevalence Research has confirmed that SSRIs can cause lasting effects on all aspects of the sexual response cycle that may persist after the drug is discontinued.5PubMed. Persistent sexual dysfunction after discontinuation of selective serotonin reuptake inhibitors
In at least one documented case specific to citalopram, a 32-year-old woman developed genital numbness and orgasmic dysfunction during just four weeks of treatment, and those symptoms persisted for over a year after stopping all antidepressant therapy.6The Open Women’s Health Journal. Prolonged Post-Treatment Genital Anesthesia and Sexual Dysfunction Following Discontinuation of Citalopram and the Atypical Antidepressant Nefazodone It is likely that persistent post-treatment sexual problems are underreported, because patients may not connect ongoing symptoms to a drug they are no longer taking, and doctors may not ask. If you notice sexual changes during treatment, bringing them up early gives you more options, including dose adjustments or switching medications.
The Heart Rhythm Concern
Among the side effects that genuinely changed how citalopram is prescribed, the heart-rhythm issue stands out. Both the manufacturer and the FDA issued warnings about citalopram causing a prolongation of the QT interval on an electrocardiogram, particularly at doses above 40 mg per day.7PubMed. Citalopram, QTc interval prolongation, and torsade de pointes. How should we apply the recent FDA ruling? A prolonged QT interval matters because it increases the risk of a dangerous heart rhythm called torsade de pointes, which can cause fainting or, in rare cases, sudden cardiac arrest.
This is the reason citalopram now has a recommended maximum dose of 40 mg per day for most adults and 20 mg per day for people over 60. If you are on other medications that also affect heart rhythm, or if you have an existing heart condition, your prescriber should be weighing this risk carefully. Cardiovascular disturbances including changes in heart rate and blood pressure are listed among the potentially serious adverse events of newer antidepressants more broadly.8Karger Publishers (Psychotherapy and Psychosomatics). The Safety, Tolerability and Risks Associated with the Use of Newer Generation Antidepressant Drugs: A Critical Review of the Literature
Weight and Metabolism
Weight change on citalopram follows an unexpected pattern. During the first few months of treatment, SSRIs as a class actually tend to produce slight weight loss on average.9JAMA Psychiatry. An Electronic Health Records Study of Long-Term Weight Gain Following Antidepressant Use This can be partly explained by the appetite-suppressing nausea that many people experience early on. Over the longer term, however, many people report gradual weight gain. The same large electronic-health-records study that documented short-term weight loss found that the trajectory shifts with continued use, and weight gain becomes a more common concern over months and years of treatment.
If you are starting citalopram and worried about weight, it helps to know that the pattern is not “immediate gain.” But if you notice the scale creeping up after several months, that is a recognized trend with this class of medication and worth discussing with your prescriber.
Emotional Blunting
Some people describe an effect that sits somewhere between side effect and overcorrection: a flattening of emotions where both the highs and the lows feel dulled. This emotional blunting was described across 25 studies as a persistent reduction in both positive and negative feelings. Patients could distinguish it from their depression symptoms, experiencing it as a separate, drug-related phenomenon.10PubMed Central. Can antidepressant use be associated with emotional blunting in a subset of patients with depression? A scoping review of available literature
The challenge is that the literature has not cleanly separated emotional blunting caused by the antidepressant from residual symptoms of the depression itself. Many people with depression experience emotional numbness as part of the illness. So when you are on treatment and feel emotionally flat, it can be hard to tell whether the drug is helping incompletely or actively making things worse. Common strategies to manage this include lowering the dose or switching to a different antidepressant, which suggests that in clinical practice, prescribers treat this as a genuine side effect often enough to have developed a playbook for it.
Low Sodium Levels
Hyponatremia, a drop in blood sodium, is a side effect that gets less public attention than it deserves, especially for older adults. In a large retrospective study, roughly one in six patients newly prescribed citalopram developed hyponatremia. The risk was significantly associated with older age, lower baseline sodium levels, use of thiazide diuretics, and male sex.11PubMed Central. Factors Associated with Hyponatremia in Patients Newly Prescribed Citalopram: A Retrospective Observational Study In most of those cases, the sodium drop may have been mild and clinically unnoticed. But in severe cases, the consequences are serious.
One case report described a 61-year-old man who developed confusion and a seizure two weeks after starting citalopram at a standard 20 mg dose. His lab results revealed dangerously low sodium levels consistent with inappropriate antidiuretic hormone secretion, a known mechanism by which SSRIs can drive sodium down.12PubMed Central. Severe symptomatic hyponatremia during citalopram therapy–a case report The risk is highest during the first weeks of treatment, making early monitoring especially valuable in older patients. If you are over 60 and starting citalopram, ask your doctor about checking your sodium levels in the first couple of weeks.
Bleeding Risk
SSRIs interfere with how platelets handle serotonin, which is part of the clotting process. The clinical result is a measurably higher risk of gastrointestinal bleeding. A systematic review and meta-analysis found that citalopram was associated with about a 38% increased odds of gastrointestinal bleeding compared to non-users, putting it among the higher-risk SSRIs alongside fluoxetine.13PubMed Central. Risk of gastrointestinal bleeding by specific SSRIs and SNRIs: A systematic review and meta-analysis
This does not mean that taking citalopram will make you bleed. The absolute risk remains small for most people. But it becomes practically important if you are also taking blood thinners, aspirin, or nonsteroidal anti-inflammatory drugs, because those medications compound the effect. Anyone on combination therapy should be aware of this overlap.
Bone Density
An underappreciated long-term consideration is bone health. Daily SSRI use was associated with about a 4% lower bone mineral density at the hip compared to non-users in one large study.14JAMA Internal Medicine. Effect of Selective Serotonin Reuptake Inhibitors on the Risk of Fracture A 4% reduction does not sound dramatic, but for someone who is already at risk for osteoporosis, particularly postmenopausal women or older adults, it nudges the needle in the wrong direction. Broader reviews have listed osteoporosis and fracture risk among the potentially serious long-term adverse events of SSRI therapy.15Karger Publishers (Psychotherapy and Psychosomatics). The Safety, Tolerability and Risks Associated with the Use of Newer Generation Antidepressant Drugs: A Critical Review of the Literature This is not a reason to avoid citalopram, but if you are going to be on it for years, bone density is worth monitoring.
Serotonin Syndrome and Drug Interactions
Citalopram raises serotonin levels in the brain. If you take another drug that also raises serotonin, the combined effect can push levels into a dangerous range, triggering serotonin syndrome. Symptoms include agitation, confusion, rapid heart rate, tremors, jerking muscle movements, and in severe cases, high fever and seizures.16PubMed. Serotonin toxicity: a short review of the literature and two case reports involving citalopram
The list of drugs that can interact is broader than many people expect. It includes not just other antidepressants (especially MAO inhibitors and tricyclics) but also certain pain medications, migraine drugs, cough suppressants, and even some herbal supplements like St. John’s wort. One reported case involved a 65-year-old patient on citalopram who developed serotonin syndrome after being started on fentanyl for pain; all symptoms resolved once fentanyl was stopped.17PubMed. Serotonin syndrome caused by interaction between citalopram and fentanyl Two other cases involved citalopram interacting with cimetidine and topiramate, which block the liver enzyme CYP2D6 and can effectively raise citalopram levels in the blood.18PubMed. Serotonin toxicity: a short review of the literature and two case reports involving citalopram Whenever you add a new medication, including over-the-counter ones, make sure your pharmacist or doctor checks for serotonin-related interactions.
Stopping Citalopram and Withdrawal Symptoms
Discontinuation symptoms are common enough that they have their own informal lexicon. “Brain zaps,” the electrical-shock sensations in the head, are perhaps the most distinctive and widely reported withdrawal symptom of SSRIs. A large international survey of people going through SSRI withdrawal found that dizziness, brain zaps, irritability, and anxiety showed the largest increase in severity during withdrawal compared to baseline. Nearly all participants reported worsening in at least one of those four symptoms.19PubMed. Establishing Core Symptoms of Acute Serotonin Reuptake Inhibitor Withdrawal: Results from an International Survey of Online Peer-Support Communities
These symptoms are not a sign of addiction. They reflect the brain readjusting to the absence of the drug it has adapted to. Tapering slowly, meaning reducing the dose in small steps over weeks or months rather than stopping abruptly, can significantly reduce the intensity of withdrawal. If your doctor recommends stopping citalopram, ask specifically about a tapering schedule.
Pregnancy Considerations
Use of citalopram during pregnancy, especially in the later stages, has been linked to what is called poor neonatal adaptation syndrome. Newborns exposed to the drug in the third trimester may show irritability, feeding difficulties, and respiratory issues shortly after birth, though these symptoms tend to be self-limiting.20PubMed. Citalopram use in pregnancy: prospective comparative evaluation of pregnancy and fetal outcome A broader review of SSRI use during pregnancy also found associations with persistent pulmonary hypertension of the newborn, a more serious but rarer complication.21PubMed. Safety concerns associated with the use of serotonin reuptake inhibitors and other serotonergic/noradrenergic antidepressants during pregnancy: a review
None of this means citalopram is automatically off-limits during pregnancy. Untreated depression during pregnancy carries its own risks, including preterm birth and low birth weight. The decision involves weighing the risks of the medication against the risks of untreated illness, and it is one that should be made individually with an obstetrician and psychiatrist rather than based on headlines.
Why Side Effects Vary So Much Between People
One of the most frustrating aspects of citalopram is how unpredictably side effects hit. Your friend takes it with no issues; you feel terrible. Part of the explanation lies in genetics, specifically the CYP2C19 liver enzyme that metabolizes citalopram. People whose genetics make them slow metabolizers of this enzyme end up with higher drug levels in their blood at the same prescribed dose, which translates into more side effects. A large-scale analysis found that slower CYP2C19 metabolizers taking citalopram were significantly more likely to report side effects and to discontinue treatment because of them.22The Pharmacogenomics Journal. Large-scale analysis demonstrates the influence of CYP2C19 genotype on specific SSRI side effects In practical terms, about a quarter of people with faster metabolism stopped due to side effects, while about a quarter of people with slower metabolism did the same, but the rate was meaningfully higher in the slow-metabolizer group.
Another study found that patients carrying a specific inactive variant of the CYP2C19 gene had significantly lower odds of tolerating citalopram.23PubMed Central. CYP2C19 variation and citalopram response Serotonin transporter gene variants also play a role: studies have found that patients with certain genotypes experience more side effects like insomnia or agitation on SSRIs, and those with other genotypes have increased overall adverse effects leading to treatment discontinuation.24JAMA Psychiatry. Association Between a Functional Serotonin Transporter Promoter Polymorphism and Citalopram Treatment in Adult Outpatients With Major Depression Pharmacogenomic testing is commercially available and can identify your CYP2C19 status before you start treatment. It is not a perfect predictor, but it can help explain why a standard dose works well for some people and is intolerable for others.
Citalopram Versus Escitalopram
If you have heard that escitalopram is “basically the same drug,” that is close but not quite right. Citalopram is a mixture of two mirror-image molecules. Escitalopram is just the active one, isolated and sold on its own. The practical difference is that escitalopram does not block histamine receptors, while citalopram is a mild histamine antagonist.25Psychopharmacology Institute. Citalopram and Escitalopram: A Summary of Key Differences and Similarities Histamine blocking is what causes drowsiness in drugs like diphenhydramine, so this may partly explain why some people feel more sedated on citalopram than escitalopram. Escitalopram was developed specifically with the goal of better tolerability, and it does not carry the same degree of QT-prolongation concern at therapeutic doses. If side effects are a problem on citalopram, escitalopram is often the first alternative your doctor will consider.
Eye and Ear Effects
Two uncommon but worth-knowing side effects involve the senses. An analysis of the FDA’s adverse event reporting database found that SSRIs as a class were significantly associated with eye disorders, and citalopram specifically showed a higher signal for angle-closure glaucoma compared to other SSRIs.26PubMed. Eye disorders associated with selective serotonin reuptake inhibitors: a real-world disproportionality analysis of FDA adverse event reporting system Angle-closure glaucoma involves a sudden increase in eye pressure and is a medical emergency. If you have narrow angles or are at risk for glaucoma, this warrants a conversation with your ophthalmologist before starting the medication.
Tinnitus, a persistent ringing or buzzing in the ears, has also been reported in connection with citalopram use. Case reports include at least one instance of an adolescent developing tinnitus on the medication. The broader review of SSRI-class side effects also lists sweating, urinary retention, and elevated prolactin levels as documented adverse events, though none of these are common enough to be considered typical complaints.27Karger Publishers (Psychotherapy and Psychosomatics). The Safety, Tolerability and Risks Associated with the Use of Newer Generation Antidepressant Drugs: A Critical Review of the Literature The reason to mention these rarer effects is that people experiencing them may not connect the symptom to their antidepressant, and that delay in recognition can mean unnecessary specialist visits chasing the wrong diagnosis.