Pseudoephedrine and Linezolid Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Linezolid Injection
Pseudoephedrine
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.
What happens
Hypertensive crisis (headache, hyperpyrexia, hypertension)
Interaction Deep Dive
Concomitant use of pseudoephedrine and MAOIs is contraindicated as this may increase the risk of hypertensive crisis. Do not use pseudoephedrine while taking a MAOI and for at least 2 weeks after discontinuation of a MAOI1. Sympathomimetics with indirect/mixed activity such as pseudoephedrine cause the release of norepinephrine, and the use of MAOIs results in more norepinephrine being made available at nerve receptor sites through inhibition of catecholamine degradation; concurrent use leads to greater amounts of norepinephrine which increases sympathetic activity 2. Coadministration of indirect-acting sympathomimetics and MAOIs has resulted in serious hypertension 3456.
Why it happens (mechanism)
Increased norepinephrine availability
Common questions
Can I take Pseudoephedrine and Linezolid Injection together?
Hypertensive crisis (headache, hyperpyrexia, hypertension) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Pseudoephedrine 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 "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Pseudoephedrine 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 (6)
- Product Information: HYCOFENIX oral solution, hydrocodone bitartrate, pseudoephedrine HCl, guaifenesin oral solution. Cintex Services (per FDA), Dallas, TX, 2015. DailyMed
- Gilman AG, Rall TW, Nies AS, et alGilman AG, Rall TW, Nies AS, et al (Eds): Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th. Macmillan Publishing Co, New York, NY, 1990.
- Smookler S & Bermudez AJ: Hypertensive crisis resulting from an MAO inhibitor and an over-the-counter appetite suppressant. Ann Emerg Med 1982; 11:482-484. PubMed
- Cuthbert MF, Greenberg MP, & Morley SW: Cough and cold remedies: a potential danger to patients on monoamine oxidase inhibitors. Br Med J 1969; 1:404-406. DOI
- Terry R, Kaye AH, & McDonald M: Sinutab (letter). Med J Aust 1975; 1:763.
- Horler AR & Wynne NA: Hypertensive crisis due to pargyline and metaraminol. Br Med J 1965; 2:460-461. PubMed
Keep reading about Linezolid Injection
Keep reading about Pseudoephedrine
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