Drug & supplement interaction

L-tryptophan + Benzhydrocodone, Acetaminophen

Benzhydrocodone, Acetaminophen brand name: Apadaz.

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

Benzhydrocodone, Acetaminophen 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?
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Interaction report

L-tryptophan and Benzhydrocodone, Acetaminophen

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. Benzhydrocodone, Acetaminophen 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 Benzhydrocodone, Acetaminophen

Benzhydrocodone, Acetaminophen 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 simple version: Apadaz contains an opioid pain reliever (the benzhydrocodone part) that already slows down your brain and nervous system. L-tryptophan, which people take for sleep and mood, can add its own drowsiness on top of that. Put them together and the sedating effects can stack up.

What that might look like for you is feeling extra sleepy, foggy, or dizzy, plus deeper concern with opioids: slowed, shallow breathing if things get too calm. This isn't about the supplement changing how your liver processes the drug, it's about two things that both relax you working at the same time. The connection is reasonable but not heavily studied, so don't panic. Just check with your pharmacist or doctor before combining them, and avoid driving until you know how you feel.

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

Benzhydrocodone, Acetaminophen 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 thing to know about Apadaz (benzhydrocodone with acetaminophen): the opioid part can mildly nudge serotonin levels in your brain. L-tryptophan is the raw material your body turns into serotonin. So putting the two together could, in theory, stack up serotonin a bit more than either one alone.

In rare cases, too much serotonin activity can lead to what we call serotonin syndrome, with things like agitation, a racing heart, sweating, shivering, muscle twitching, or feeling confused. I want to be honest though: this concern is theoretical, based on how these substances work rather than strong real-world reports, so most people won't run into trouble. Still, since both affect serotonin, please run this combo by your pharmacist or doctor before pairing them, and watch for those symptoms.

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 Benzhydrocodone, Acetaminophen 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. Benzhydrocodone, Acetaminophen)
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 Benzhydrocodone, Acetaminophen

This page covers L-tryptophan only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Benzhydrocodone, Acetaminophen page lists 299 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), Asarabacca (major), Beer (major) and Gamma-hydroxybutyrate (ghb) (major).

By severity: 14 major · 239 moderate · 46 minor.

Open the Benzhydrocodone, Acetaminophen 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 Benzhydrocodone, Acetaminophen 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 Benzhydrocodone, Acetaminophen 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

#1,037 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Benzhydrocodone, Acetaminophen
Steady interest

#2,290 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 Benzhydrocodone and Acetaminophen

What Is Benzhydrocodone and Acetaminophen Used For?

Brand name: Apadaz

Apadaz is indicated for the short-term management of acute pain — up to 14 days — that is severe enough to require an opioid and for which non-opioid treatments have not worked or are not expected to work. It combines benzhydrocodone (a prodrug that converts to the opioid hydrocodone) with acetaminophen.

Because of serious risks including addiction, abuse, and misuse, Apadaz is reserved for patients who have not tolerated or have not gotten adequate relief from alternative pain treatments. It should not be used for an extended period of time unless the pain remains severe enough to require an opioid and alternatives remain inadequate.

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

Can you take L-tryptophan with Benzhydrocodone, Acetaminophen?
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 Benzhydrocodone, Acetaminophen?
Benzhydrocodone, Acetaminophen 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 Benzhydrocodone, Acetaminophen 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

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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.