Citalopram: what it treats, how to take it, side effects
Last updated September 3, 2026.
Citalopram is an SSRI antidepressant with one job on the label and a strict dose ceiling. You may know it as Celexa. It increases serotonin in the brain, and above 40 mg a day it can disturb the heart's rhythm - which is why the cap exists.
What does it treat?
Depression is the labeled use. MedlinePlus also lists OCD, eating disorders, panic disorder, premenstrual dysphoric disorder, social anxiety disorder, PTSD, diabetic nerve tingling, and certain male sexual problems as other uses.
How do you take it?
Once a day, morning or evening, with or without food, same time every day. Your doctor may start low and increase no more than once a week. The label is firm on the ceiling: 40 mg a day is the maximum because of heart-rhythm risk, and 20 mg is the maximum for people over 60, those with liver impairment, poor metabolizers, or anyone taking cimetidine or another CYP2C19 inhibitor. Full benefit takes several weeks. Do not stop suddenly: withdrawal brings mood changes, irritability, agitation, dizziness, numbness, tingling or electric-shock sensations in the hands or feet, anxiety, confusion, headache, tiredness, nausea, sweating, shaking, and insomnia. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: nausea, drowsiness, and sexual problems in both men and women.
- Serious: chest pain, shortness of breath, dizziness, or fainting (the heart-rhythm signal - report these, do not wait); the serotonin-syndrome cluster of fever, sweating, confusion, fast or irregular heartbeat, severe muscle stiffness or twitching, agitation, hallucinations, loss of coordination, nausea, vomiting, or diarrhea; allergic reactions with facial or throat swelling or trouble breathing; unusual bleeding or bruising; headache with unsteadiness and thinking or memory problems; and seizures. Angle-closure glaucoma: eye pain, nausea, colored rings around lights, and eye swelling or redness mean emergency care. The boxed warning covers increased suicidal thoughts and actions in people under 24.
Who should not take it?
Anyone who has taken an MAO inhibitor, linezolid, or methylene blue within the past two weeks, and anyone with congenital long QT syndrome. The label also rules it out with slow heartbeat, recent heart attack, uncompensated heart failure, or low potassium or magnesium, and with other QT-prolonging drugs like certain antiarrhythmics, antipsychotics, and antibiotics. Flag heavy alcohol use, bleeding problems, stroke, seizures, and kidney or liver disease. Your doctor may order an EKG and lab tests before and during treatment. It can make you drowsy and affect judgment - no driving until you know it. Alcohol worsens its side effects. Pregnancy, especially the last few months, and breastfeeding need a direct call with your doctor.
When is it an emergency?
Call 911 for seizures, fainting, or trouble breathing or swallowing. A racing or irregular heartbeat with dizziness or fainting, and the serotonin-syndrome cluster, mean immediate care. Thoughts of harming or killing yourself mean calling your doctor right away - or call or text 988, the Suicide and Crisis Lifeline, any time. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Why is there a 40 mg limit on citalopram?
Heart rhythm. The label says citalopram causes dose-dependent QT prolongation - an electrical change linked to a dangerous arrhythmia - so it should not be given above 40 mg a day. The cap drops to 20 mg for people over 60, liver impairment, poor metabolizers, or those taking cimetidine or similar inhibitors. This is one antidepressant where more is genuinely not better.
How is citalopram different from escitalopram?
Escitalopram (Lexapro) is the active half of the citalopram molecule, isolated. They share the SSRI mechanism and side effect map, but escitalopram runs at roughly half the milligram dose for the same effect. Which one you get is your doctor's call, often steered by insurance and prior response.
How long does citalopram take to work?
MedlinePlus says several weeks before you notice the full benefit, with dose increases no more than once a week. Early nausea or drowsiness usually shows up first and fades. Give the starting dose an honest month before judging it.
Can I drink alcohol while taking citalopram?
MedlinePlus says to talk to your doctor about the safe use of alcohol, because alcohol can make citalopram's side effects worse, and to disclose heavy drinking before starting. The drowsiness and judgment effects stack, so the practical answer is minimal or none.
Why does my doctor want an EKG before prescribing citalopram?
Because of the QT-prolongation risk. MedlinePlus says your doctor may order lab tests and electrocardiograms before and during treatment, and the label lists the heart conditions and low potassium or magnesium states where citalopram should not be used at all. The EKG is how your doctor confirms the drug is safe for your heart specifically.
What happens if I miss a dose of citalopram?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. Its long half-life makes it more forgiving than paroxetine or venlafaxine on a single missed dose, but a consistent daily time is still the right habit.