Drug & supplement interaction

L-tryptophan + Lorazepam

Lorazepam brand name: Ativan.

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

L-tryptophan has a major interaction with Lorazepam. Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

L-tryptophan and Lorazepam

Here is the interaction we found between these two, with the evidence behind it.

Major

CNS DEPRESSANTS

Why this applies to Lorazepam

Lorazepam 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 know if you're pairing L-tryptophan with lorazepam (Ativan). Lorazepam is a benzodiazepine that calms brain activity, which is why it eases anxiety and helps you sleep. L-tryptophan can cause its own drowsiness and fatigue on top of that. So when you take them together, the sleepy effects can stack up. This isn't about one changing how the other is broken down. It's simply two calming agents adding up.

What that can look like is feeling extra drowsy, foggy, dizzy, or unsteady, which raises the risk of falls or slowed reactions behind the wheel. Please don't start or stop either one on your own. Have a quick chat with your pharmacist or doctor first so they can guide you safely.

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

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 Lorazepam one above is one of them. If you take anything else, check it against the full list below.

Major 247 Moderate 146 No known interaction 2,437 (incl. Lorazepam)
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.

From our Q&A

Questions About L-tryptophan or Lorazepam

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers L-tryptophan or Lorazepam, 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 Lorazepam

This page covers L-tryptophan only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Lorazepam page lists 119 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 8 major · 94 moderate · 17 minor.

From our pharmacist’s overview on the Lorazepam page

“Lorazepam (Ativan) works by slowing brain activity, and that is exactly why this list deserves real caution. Of the 119 supplement and herbal ingredients on file, 78 are themselves nervous-system depressants, so adding them can deepen drowsiness or, at the extreme, slow breathing.”

Reviewed by 2 · Jul 18, 2026

Open the Lorazepam 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 Lorazepam 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 Lorazepam 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

#1,030 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Lorazepam
Top 25%

#551 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 Lorazepam

What Is Lorazepam Used For?

Brand name: Ativan

Lorazepam tablets (Ativan and generic) and the oral solution are used to manage anxiety disorders or for short-term relief of anxiety symptoms, including anxiety that comes with depressive symptoms. Loreev XR, an extended-release capsule, is specifically indicated for adults with anxiety disorders who are already stable on lorazepam tablets taken three times daily.

Ativan and generic lorazepam injections are used in two additional situations: treating status epilepticus (a medical emergency involving prolonged or repeated seizures) and as a pre-surgery medication in adults to produce sedation, ease anxiety, and reduce memory of events on the day of surgery.

See full Lorazepam 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 Lorazepam, 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 Lorazepam supplement interactions › Every supplement checked against Lorazepam, ranked by severity Lorazepam 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 Lorazepam Together: Common Questions

Can you take L-tryptophan with Lorazepam?
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.
How serious is the L-tryptophan and Lorazepam 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 Lorazepam and L-tryptophan?

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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.