The short answer
Review melatonin before adding it to citalopram, especially with opioids or other medicines affecting alertness. Severe sedation has been reported in a multi-medicine regimen.
What this answer covers
Oral melatonin; one 3 mg product in a polypharmacy case, not every formulation.
- Supplement or preparation
- Melatonin
- Medication ingredient
- citalopram
What the reported case shows
Severe sedation occurred after melatonin was added to citalopram, nortriptyline and oxycodone. Symptoms improved when melatonin stopped and worsened when it restarted; complete resolution also required stopping oxycodone.
The mechanism remains uncertain
The case had no blood drug measurements. It cannot prove that melatonin raised citalopram levels or estimate how often the problem occurs.
A negative finding limits a broad enzyme claim
Citalopram did not raise naturally produced melatonin in a small healthy-volunteer study. That finding does not test a melatonin supplement, but cautions against assuming all antidepressants act alike.
Watch for impaired alertness
Citalopram can affect alertness and coordination. Avoid driving if affected and contact the prescriber if added sleepiness, confusion or unsteadiness appears after a new product. Severe confusion, fainting or inability to wake needs urgent assessment.
Evidence and practical considerations
Side effects & toxicity
A direct but confounded report supports conditional sedation review, not a quantified isolated interaction.
- Exact scope
- Oral melatonin; one 3 mg product in a polypharmacy case, not every formulation. with Exact oral citalopram hydrobromide film-coated tablets. RxNorm IN2556 / PIN221078 hydrobromide tablets. Racemic citalopram is distinct from escitalopram.
- Medication form and route
- oral
- Timing or duration
- Source-specific single-dose, repeated-dose and observational exposures distinguished.
What remains uncertain
- Nortriptyline and oxycodone coexposure prevents attribution to citalopram alone; no confirmed concentration mechanism.
Factors that may matter: preparation and plant part; clinical indication; dose; other medicines; baseline alertness.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral citalopram.
Label names tryptophan and St John’s wort in serotonin warnings; dose-dependent QT and electrolyte precautions are distinct from sedation and nutritional augmentation.
How this applies: RxNorm IN2556 / PIN221078 hydrobromide tablets. Racemic citalopram is distinct from escitalopram.
No universal supplement interval, event rate or preparation equivalence established.
Source 2: original case report with laboratory follow-up
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: One 19-year-old taking nortriptyline, citalopram and oxycodone.
Severe sedation improved after melatonin withdrawal and recurred with rechallenge; full clearance also required oxycodone discontinuation.
How this applies: Direct citalopram coexposure within a three-medicine regimen; not an isolated citalopram-melatonin test.
Single polypharmacy case with nortriptyline and oxycodone; no plasma drug measurements. Cannot isolate citalopram or estimate incidence.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Seven healthy participants in crossover experiments.
Citalopram did not significantly increase endogenous melatonin; fluvoxamine did.
How this applies: Only the named drug, preparation, route and measured endpoints apply.
No supplemental melatonin exposure, and no exact-pair sedation risk measured.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Current exact available claims adjudicated using original captures and explicit identity and comparator limits. | |
| Research summary published |
Article revision: 7d577bfa47693098
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.