Drug & supplement interaction

Melatonin + Venlafaxine

Venlafaxine brand names: Effexor XR, Effexor.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Venlafaxine falls into 2 drug categories that Melatonin can interact with; the most serious is rated moderate. Theoretically, taking melatonin with drugs that lower the seizure threshold might increase the risk of seizure activity.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Melatonin and Venlafaxine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Melatonin interacts with whole categories of medication. Venlafaxine falls into 2 of those categories, so it can interact with Melatonin in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

SEIZURE THRESHOLD LOWERING DRUGS

1 of 2

Why this applies to Venlafaxine

Venlafaxine falls under SEIZURE THRESHOLD LOWERING DRUGS — the group Melatonin interacts with.

Theoretically, taking melatonin with drugs that lower the seizure threshold might increase the risk of seizure activity.
Some clinical evidence suggests that melatonin may increase the frequency of seizures in certain patients, particularly children with neurological disabilities.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with venlafaxine (Effexor) and melatonin. Venlafaxine is one of those medicines that can slightly lower the seizure threshold, meaning it can make seizures a touch more likely in people who are prone to them. Melatonin, in theory, may do the same thing in certain folks. Stack them together and you could, in theory, add up that small risk.

I want to be honest about the strength of this one: it's theoretical, based mostly on how these act in the body, with only some signal in specific groups like children with neurological conditions. For most adults using melatonin short-term, it's unlikely to cause trouble. Still, if you have a seizure history, run it by your pharmacist or doctor before combining them. Don't change your venlafaxine on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sheldon SH. Pro-convulsant effects of oral melatonin in neurologically disabled children. Lancet 1998;351:1254. PubMed
  2. Stewart LS. Endogenous melatonin and epileptogenesis: facts and hypothesis. Int J Neurosci 2001;107:77-85.. PubMed
Minor

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 2

Venlafaxine also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, melatonin might increase levels of drugs metabolized by CYP2D6.
Laboratory research suggests that certain lots of melatonin inhibit CYP2D6. Theoretically, combined administration of melatonin with certain drugs metabolized by the CYP2D6 enzyme may reduce the metabolism of these drugs, resulting in increased serum levels. Until more is known, use melatonin cautiously in patients taking drugs metabolized by these enzymes.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for combining melatonin with your venlafaxine (Effexor). Your liver uses an enzyme called CYP2D6 to help clear venlafaxine out of your system. Some lab research hints that melatonin might slow that enzyme down a little. If that happened, venlafaxine could build up slightly, which in theory might mean more of its usual effects, such as nausea, dizziness, a faster heartbeat, jitteriness, sweating, or trouble sleeping.

I want to be honest with you, though: this is a theoretical concern based only on test-tube studies, and it's rated as minor. For most people taking sensible short-term melatonin for sleep, it's unlikely to cause a real problem. Still, since both can affect how you feel, it's worth a quick chat with your pharmacist or doctor before you start.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Foster BC, Cvijovic K, Boon HS, et al. Melatonin Interaction Resulting in Severe Sedation. J Pharm Pharm Sci 2015;18(2):124-31. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Melatonin Also Interacts With Other Medications

Melatonin has 1,115 moderate, 345 minor known drug interactions in our database — the Venlafaxine one above is among them. If you take anything else, check it against the full list below.

Moderate 1,115 Minor 345 No known interaction 1,370 (incl. Venlafaxine)
Taking anything else?

Check Another of Your Medications Against Melatonin

Covers the 2,830 medications we’ve checked against Melatonin. Pick one to open its full report.

From our Q&A

Questions About Melatonin or Venlafaxine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Melatonin or Venlafaxine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Venlafaxine

This page covers Melatonin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Venlafaxine page lists 110 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 82 moderate · 20 minor.

From our pharmacist’s overview on the Venlafaxine page

“Venlafaxine (Effexor, Effexor XR) is an antidepressant that raises serotonin, which is exactly where part of the danger on this page sits, and its 110 interactions deserve genuine respect. Eight carry a major rating, most tied to heart rhythm: several ingredients, grapefruit among them, can stretch the QT interval and add to a strain v…”

Reviewed by 2 · Jul 18, 2026

Open the Venlafaxine interaction page

One more smart check

Taking Melatonin as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2,885 real supplement products containing Melatonin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Melatonin. Your product may carry other ingredients that interact with Venlafaxine too, on top of Melatonin — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Melatonin and Venlafaxine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Melatonin
Top 5%

#55 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Venlafaxine
Top 5%

#117 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Melatonin

What is Melatonin?

Melatonin
  • Trouble falling asleep (insomnia)
  • Jet lag
  • Delayed sleep phase syndrome
  • Non-24-hour sleep-wake disorder
  • Shift-work sleep problems
  • Sleep problems in some children with conditions like autism or ADHD

Melatonin is a hormone your body makes naturally to help control your sleep-wake cycle, and the supplement form is widely used to help with sleep timing problems and jet lag. The evidence is strongest for certain circadian (body-clock) disorders and is more mixed for everyday insomnia. It is generally well tolerated for short-term use, but talk with your pharmacist or doctor before starting, especially for children or during pregnancy.

Read the full Melatonin monograph & all interactions
Medication

About Venlafaxine

What Is Venlafaxine Used For?

Brand names: Effexor XR, Effexor

Venlafaxine is used to treat major depressive disorder (MDD) across all available formulations. Extended-release capsules (including Effexor XR) are also approved for generalized anxiety disorder (GAD), social anxiety disorder (SAD), and panic disorder (PD).

Extended-release tablets are approved for major depressive disorder and social anxiety disorder. Immediate-release venlafaxine tablets are indicated for major depressive disorder only.

See full Venlafaxine drug information
Keep checking

Other Drugs & Melatonin

Browse every other medication we’ve checked against Melatonin — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
1,115Moderate
345Minor
1,369No known interaction
1,115 Moderate 345 Minor 1,369 No interaction
Moderate

1,115 interactions

Showing 60 of 1,115 moderate interactions — see all 1,115 on the Melatonin page.

Minor

345 interactions

Showing 60 of 345 minor interactions — see all 345 on the Melatonin page.

No interaction 1,369 drugs checked — show the list

We also checked Melatonin against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,369 medications checked with no known interaction — see the full Melatonin list.

See the full Melatonin interactions page
See every supplement checked against Venlafaxine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Melatonin monograph › Uses, safety, and every drug interaction in one place Venlafaxine supplement interactions › Every supplement checked against Venlafaxine, ranked by severity Venlafaxine drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Melatonin and Venlafaxine Together: Common Questions

Can you take Melatonin with Venlafaxine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Melatonin and Venlafaxine?
Venlafaxine belongs to more than one drug category, and Melatonin interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Melatonin and Venlafaxine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Venlafaxine and Melatonin?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.