Drug & supplement interaction

L-tryptophan + Metoclopramide Hydrochloride

Metoclopramide Hydrochloride brand name: Gimoti.

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

Metoclopramide Hydrochloride falls into 2 drug categories that L-tryptophan can interact with; the most serious is rated major. Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.

Read the full interaction report
SeverityMajor
LikelihoodProbable
Interactions2
EvidenceB
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

L-tryptophan and Metoclopramide Hydrochloride

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

Why Are There 2 Interactions?

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

Major

CNS DEPRESSANTS

1 of 2

Why this applies to Metoclopramide Hydrochloride

Metoclopramide Hydrochloride falls under CNS DEPRESSANTS — the group L-tryptophan interacts with.

Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.
Clinical research shows that L-tryptophan can cause fatigue and drowsiness.
Severity Major Likelihood Probable Evidence B

Interaction 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..

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

Here's the thing to keep in mind with this combo. Metoclopramide already has a known habit of making people feel drowsy, foggy, or tired. L-tryptophan can add its own sedating effect because your body turns it into serotonin and melatonin, both of which can make you sleepy. Put the two together and that drowsiness may stack up.

So you might feel more sluggish, less alert, or have a harder time driving or focusing than you would with either one alone. This is a reasonable, probable concern, not just a theory. I wouldn't change anything on your own, but please run it by your pharmacist or doctor first so they can weigh in on whether the pairing makes sense for you.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lieberman HR, Corkin S, Spring BJ. The effects of dietary neurotransmitter precursors on human behavior. Am J Clin Nutr 1985;42:366-70. PubMed
Moderate

SEROTONERGIC DRUGS

2 of 2

Metoclopramide Hydrochloride also falls under SEROTONERGIC DRUGS.

Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
L-tryptophan is a precursor to serotonin. Theoretically, combining serotonergic drugs with L-tryptophan might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders.
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: metoclopramide (Gimoti) does more than speed up your stomach. It also nudges serotonin activity in the body. L-tryptophan is a building block your body turns into serotonin, so stacking the two could, in theory, push serotonin a little higher than either one alone.

This concern is theoretical, based on how these two work rather than on lots of real-world reports, so I don't want to alarm you. Still, it's worth knowing the signs of too much serotonin: agitation, a racing heart, sweating, shivering, muscle twitching, or confusion. Metoclopramide on its own can also cause restlessness and unusual muscle movements, so watch for those too. Before combining them, please check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. J Toxicol Clin Toxicol 1993;31:603-30. PubMed
  2. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. 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

L-tryptophan Also Interacts With Other Medications

L-tryptophan has 247 major, 146 moderate known drug interactions in our database — the Metoclopramide Hydrochloride one above is among them. If you take anything else, check it against the full list below.

Major 247 Moderate 146 No known interaction 2,437 (incl. Metoclopramide Hydrochloride)
Taking anything else?

Check Another of Your Medications Against L-tryptophan

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

Everything else you take

See Every Supplement That Interacts With Metoclopramide Hydrochloride

This page covers L-tryptophan only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metoclopramide Hydrochloride page lists 135 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major), Kava (major) and Lithium (major).

By severity: 7 major · 114 moderate · 14 minor.

From our pharmacist’s overview on the Metoclopramide Hydrochloride page

“Metoclopramide (Gimoti, also sold as Reglan) calms nausea and speeds a slow stomach by acting on the brain, and that is exactly where most of these 135 supplements and herbs collide with it. This is a list to treat with genuine care.”

Reviewed by 2 · Jul 18, 2026

Open the Metoclopramide Hydrochloride interaction page

One more smart check

Taking L-tryptophan as Part of a Dietary Supplement Product? Check It for Interactions

We hold 5 real supplement products containing L-tryptophan, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-tryptophan. Your product may carry other ingredients that interact with Metoclopramide Hydrochloride too, on top of L-tryptophan — 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 L-tryptophan and Metoclopramide Hydrochloride 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 L-tryptophan
Steady interest

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

29 days ago today
Medication Metoclopramide Hydrochloride
Top half

#784 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 L-tryptophan

What is L-tryptophan?

L-tryptophan
  • Sleep problems
  • Low mood and depression
  • Anxiety
  • Premenstrual symptoms
  • Appetite and food cravings

L-tryptophan is an essential amino acid the body uses to make serotonin and melatonin, and people take it to support sleep and mood. The evidence for supplement use is limited and mixed, and there are real safety concerns, so talk to a pharmacist or doctor before trying it.

Read the full L-tryptophan monograph & all interactions
Medication

About Metoclopramide Nasal Spray

What Is Metoclopramide Nasal Spray Used For?

Brand name: Gimoti

Gimoti (metoclopramide nasal spray) is approved for adults with acute and recurrent diabetic gastroparesis — a condition where diabetes damages the nerves controlling stomach emptying, causing nausea, vomiting, and bloating. It works to relieve those symptoms by helping the stomach empty more normally.

Gimoti is not recommended for children, or for adults with moderate to severe kidney or liver disease. It is also not recommended for adults taking strong CYP2D6 inhibitor medications (certain antidepressants and other drugs that slow how the body breaks down metoclopramide).

See full Metoclopramide Nasal Spray drug information
Keep checking

Other Drugs & L-tryptophan

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

247Major
146Moderate
0Minor
2,436No known interaction
247 Major 146 Moderate 2,436 No interaction
Major

247 interactions

Showing 60 of 247 major interactions — see all 247 on the L-tryptophan page.

Moderate

146 interactions

Showing 60 of 146 moderate interactions — see all 146 on the L-tryptophan page.

No interaction 2,436 drugs checked — show the list

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

Showing the 60 most looked-up of 2,436 medications checked with no known interaction — see the full L-tryptophan list.

See the full L-tryptophan interactions page
See every supplement checked against Metoclopramide Hydrochloride, 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
L-tryptophan monograph › Uses, safety, and every drug interaction in one place Metoclopramide Hydrochloride supplement interactions › Every supplement checked against Metoclopramide Hydrochloride, ranked by severity Metoclopramide Nasal Spray 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 L-tryptophan and Metoclopramide Hydrochloride Together: Common Questions

Can you take L-tryptophan with Metoclopramide Hydrochloride?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for L-tryptophan and Metoclopramide Hydrochloride?
Metoclopramide Hydrochloride belongs to more than one drug category, and L-tryptophan 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 L-tryptophan and Metoclopramide Hydrochloride interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Metoclopramide Hydrochloride and L-tryptophan?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.