Drug & supplement interaction

5-htp + Linezolid

Linezolid brand names: Zyvox, Zyvox Injection.

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

5-htp has a moderate interaction with Linezolid. Combining serotonergic drugs with 5-HTP might cause additive serotonergic effects.

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

5-htp and Linezolid

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

Moderate

SEROTONERGIC DRUGS

Why this applies to Linezolid

Linezolid falls under SEROTONERGIC DRUGS — the group 5-htp interacts with.

Combining serotonergic drugs with 5-HTP might cause additive serotonergic effects.
5-HTP can increase serotonin levels and cause serotonergic effects. Theoretically, combining serotonergic drugs with 5-HTP might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders. However, serotonin syndrome with 5-HTP has not yet been reported in humans. Monitor patients for signs of serotonin syndrome and other serotonergic side effects if using 5-HTP with serotonergic drugs.
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 about linezolid: besides killing bacteria, it also acts as a mild MAO inhibitor, which means it slows the breakdown of serotonin in your body. Since 5-HTP is a direct building block your body turns into serotonin, taking the two together could stack up serotonin more than either alone. That raises the theoretical risk of serotonin syndrome, which can show up as agitation, a racing heart, sweating, shivering, muscle twitching, or confusion.

To be fair, this is based on pharmacology, not real-world reports, and serotonin syndrome from 5-HTP hasn't actually been documented in people. Still, linezolid is one of the medicines where doctors take serotonin caution seriously. Please check with your pharmacist or doctor before pairing these, and don't stop your antibiotic on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Birdsall TC. 5-Hydroxytryptophan: A Clinically-Effective Serotonin Precursor. Altern Med Rev 1998;3:271-80.
  2. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
  3. Maffei ME. 5-Hydroxytryptophan (5-HTP): Natural Occurrence, Analysis, Biosynthesis, Biotechnology, Physiology and Toxicology. Int J Mol Sci. 2020;22(1):181. 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

5-htp Also Interacts With Other Medications

5-htp has 397 moderate known drug interactions in our database — the Linezolid one above is one of them. If you take anything else, check it against the full list below.

Moderate 397 No known interaction 2,433 (incl. Linezolid)
Taking anything else?

Check Another of Your Medications Against 5-htp

Covers the 2,830 medications we’ve checked against 5-htp. Pick one to open its full report.

From our Q&A

Questions About 5-htp or Linezolid

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers 5-htp or Linezolid, 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 Linezolid

This page covers 5-htp only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Linezolid page lists 65 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Lithium (major), Acetyl-l-carnitine (moderate), Ayahuasca (moderate) and Bacillus Coagulans (moderate).

By severity: 2 major · 51 moderate · 12 minor.

From our pharmacist’s overview on the Linezolid page

“Linezolid (Zyvox) fights serious infections, but it also blocks an enzyme called monoamine oxidase, which is why I treat this page with real respect. Twenty of the 65 supplements here raise serotonin, and stacking them on linezolid risks serotonin syndrome, a dangerous overload of that chemical.”

Reviewed by 2 · Jul 18, 2026

Open the Linezolid interaction page

One more smart check

Taking 5-htp as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,651 real supplement products containing 5-htp, each one broken down to its full ingredient list — and combination products often carry several ingredients besides 5-htp. Your product may carry other ingredients that interact with Linezolid too, on top of 5-htp — 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 5-htp and Linezolid 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 5-htp
Top 10%

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

29 days ago today
Medication Linezolid
Steady interest

#2,377 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 5-htp

What is 5-htp?

5-htp
  • Low mood or depression
  • Anxiety and stress
  • Sleep problems
  • Migraine headaches
  • Fibromyalgia
  • Appetite or weight management

5-HTP is a compound your body uses to make serotonin, and people take it as a supplement hoping to improve mood, sleep, and headaches. Some early research is promising, but the overall evidence is limited and not conclusive. Because it can affect serotonin and may interact with medicines, talk to your pharmacist or doctor before using it.

Read the full 5-htp monograph & all interactions
Medication

About Linezolid

What Is Linezolid Used For?

Brand names: Zyvox, Zyvox Injection

Linezolid — available as Zyvox and in generic forms — is used to treat infections caused by certain drug-resistant Gram-positive bacteria. It is approved for adults and children for nosocomial pneumonia (hospital-acquired lung infection), community-acquired pneumonia, complicated skin and skin structure infections (including diabetic foot infections, but only when bone infection is not also present), uncomplicated skin and skin structure infections, and vancomycin-resistant Enterococcus faecium infections.

It is important to know that linezolid does not work against Gram-negative bacteria. If a Gram-negative infection is also present or suspected, a separate antibiotic must be started right away. Linezolid should only be used for infections that are confirmed or strongly suspected to be caused by bacteria, to help prevent antibiotic resistance.

See full Linezolid drug information
Keep checking

Other Drugs & 5-htp

Browse every other medication we’ve checked against 5-htp — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
397Moderate
0Minor
2,432No known interaction
397 Moderate 2,432 No interaction
Moderate

397 interactions

Showing 60 of 397 moderate interactions — see all 397 on the 5-htp page.

No interaction 2,432 drugs checked — show the list

We also checked 5-htp against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,432 medications checked with no known interaction — see the full 5-htp list.

See the full 5-htp interactions page
See every supplement checked against Linezolid, 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
5-htp monograph › Uses, safety, and every drug interaction in one place Linezolid supplement interactions › Every supplement checked against Linezolid, ranked by severity Linezolid 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 5-htp and Linezolid Together: Common Questions

Can you take 5-htp with Linezolid?
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.
How serious is the 5-htp and Linezolid 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 Linezolid and 5-htp?

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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.