Drug Interaction Report

Secobarbital and Doxycycline Injection: Interaction Details

A pharmacist-reviewed analysis of the Secobarbital and Doxycycline 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

Secobarbital

No brand names on record
+

Doxycycline Injection

Acticlate Adoxa Alodox Avidoxy Doryx Doxy Doxy 100® Doxy 200®
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
Major
Potentially serious — often needs a change or close monitoring.
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 40 documented Secobarbital interactions, 30 are rated major — 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
probable
Severity
Major

What happens

Reduced doxycycline exposure and reduced efficacy of doxycycline

Interaction Deep Dive

In a number of case reports, the concurrent administration of PHENobarbital (greater than 5 days) resulted in the doxycycline half-life changing from 15 to 11 hours (in one reported case, 8 hours). The antibiotic effect of doxycycline could be compromised in patients on PHENobarbital2. Concomitant use of doxycycline and barbiturates may reduce doxycycline exposure and thus may reduce efficacy of doxycycline 1.

Why it happens (mechanism)

Increased hepatic metabolism

Literature reports

1 report — tap to read

a) In a number of case reports, the concurrent administration of PHENobarbital (greater than 5 days) resulted in the doxycycline half-life changing from 15 to 11 hours (in one reported case, 8 hours). The antibiotic effect of doxycycline could be compromised in patients on PHENobarbital 2.

Common questions

Can I take Secobarbital and Doxycycline Injection together?

Reduced doxycycline exposure and reduced efficacy of doxycycline Always confirm with your pharmacist or prescriber before making any change.

How serious is the Secobarbital and Doxycycline Injection interaction?

It is rated major. Potentially serious — often needs a change or close monitoring.

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 "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

  • Does my dose of Secobarbital or Doxycycline 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 (2)

  1. Product Information: ORACEA(R) oral capsules, doxycycline oral capsules. Galderma Laboratories, L.P. (per DailyMed), Dallas, TX, 2025. DailyMed
  2. Neuvonen PJ & Penttila O: Interaction between doxycycline and barbiturates. Br Med J 1974; 1:535-536. DOI
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Secobarbital

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All Secobarbital interactions (40)
Also serious with: Estradiol Transdermal Patch Nalbuphine Injection Cetirizine Ophthalmic Butorphanol Injection
Doxycycline Injection

Keep reading about Doxycycline Injection

All Doxycycline Injection interactions (118) Doxycycline Injection drug information
Also serious with: Acitretin Acenocoumarol Amobarbital Amoxicillin

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