Drug Interaction Report

Cyproheptadine and Linezolid Injection: Interaction Details

A pharmacist-reviewed analysis of the Cyproheptadine and Linezolid Injection interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Cyproheptadine

No brand names on record
+

Linezolid Injection

Zyvox Zyvox®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Contraindicated
These should generally not be used together.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 30 documented Cyproheptadine interactions, 1 is rated contraindicated — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
delayed
Evidence
theoretical
Severity
Contraindicated

What happens

Prolonged and intensified anticholinergic effects and an increased cyproheptadine effects

Interaction Deep Dive

Concurrent use of cyproheptadine (antihistamine) and monoamine oxidase inhibitors is contraindicated. Concomitant cyproheptadine and MAO inhibitor therapy may prolong and intensify the anticholinergic effects of cyproheptadine123.

Why it happens (mechanism)

Unknown

Literature reports

1 report — tap to read

a) Concomitant use of cyproheptadine (2 mg HS) and phenelzine (30 mg daily) was reported to result in visual hallucinations in a 30-year-old woman with bulimia and depression. Withdrawal of both drugs resulted in subsidence of symptoms within 48 hours. The patient was subsequently treated with lithium and desipramine without recurrence of hallucinations 4.

Common questions

Can I take Cyproheptadine and Linezolid Injection together?

Prolonged and intensified anticholinergic effects and an increased cyproheptadine effects Always confirm with your pharmacist or prescriber before making any change.

How serious is the Cyproheptadine and Linezolid Injection interaction?

It is rated contraindicated. These should generally not be used together.

How quickly could this interaction happen?

The documented onset is "delayed". Effects tend to build up gradually over days to weeks.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Cyproheptadine or Linezolid Injection need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there a safer alternative to one of these medications for me?

References (4)

  1. Product Information: Cyproheptadine HCl oral solution, cyproheptadine HCl oral solution. Lannett Company Inc (per DailyMed), Philadelphia, PA, 2017.
  2. AMA Department of DrugsAMA Department of Drugs: Drug Evaluations Subscription, American Medical Association, Chicago, IL, 1991.
  3. Product Information: Periactin(R), cyproheptadine. Merck & Co. Inc. West Point, PA, 1996. DailyMed
  4. Kahn DA: Possible toxic interaction between cyproheptadine and phenelzine. Am J Psychiatry 1987; 144:1242-1243. PubMed
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Cyproheptadine

Keep reading about Cyproheptadine

All Cyproheptadine interactions (30)
Also serious with: Glucagon Injection / Solution Buprenorphine Nalbuphine Injection Fentanyl Transdermal Patch
Linezolid Injection

Keep reading about Linezolid Injection

All Linezolid Injection interactions (212) Linezolid Injection drug information
Also serious with: Tramadol Tranylcypromine Trazodone Trimipramine
Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Cyproheptadine + Activated Charcoal Henbane Scopolia Alfalfa Angel's Trumpet Angelica Archangelica Arrach Bacopa + 64 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.