Acetaminophen And Codeine and Saquinavir: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 1, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Saquinavir
No brand names on record
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's going on: Your pain medicine contains codeine, which your body turns into morphine (its active pain-relieving form). Saquinavir, an HIV medicine, can slow down one of the enzymes that handles codeine. This can let more codeine and morphine build up in your body than expected.
When opioid levels run high, you can feel very drowsy or your breathing can slow down, which can be dangerous. This is based on theory, not proven cases, so try not to worry. The good news is your care team can manage this by watching you closely and adjusting your codeine dose if needed. Keep taking both as prescribed and tell your doctor or pharmacist if you feel unusually sleepy or short of breath.
Mechanism: Saquinavir inhibits CYP3A4, reducing one clearance pathway for codeine. This can increase codeine and its active metabolite morphine exposure, raising the risk of excessive sedation and potentially fatal respiratory depression.
- Direction: Increased opioid effect (increased codeine/morphine concentrations).
- Evidence: Theoretical; magnitude not quantified.
- Onset: Unspecified.
- Management: If co-use is needed, monitor for respiratory depression and sedation; consider codeine dose reduction until stable effects are seen. If saquinavir is discontinued, monitor for opioid withdrawal and consider increasing the codeine dose. Individualize dosing to the patient.
What happens
Increased codeine and morphine exposure
Interaction Deep Dive
Taking codeine together with CYP3A4 inhibitors has produced elevated levels of both codeine and morphine, an effect that may intensify or extend adverse reactions and can lead to respiratory depression that is potentially fatal, especially in cases where an inhibitor is introduced after the patient has already reached a stable codeine dose. When the two must be used together, watch patients carefully for sedation and respiratory depression, and think about lowering the codeine dose until stable drug effects are seen. In situations where a CYP3A4 inhibitor is being stopped, observe patients for indications of opioid withdrawal, and consider raising the codeine dose until stable drug effects are observed12.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated codeine metabolism
How to manage this interaction
You can usually take both, with care. Keep taking your medicines exactly as prescribed unless your care team tells you otherwise.
- Your team may monitor you more closely for excessive drowsiness or slowed breathing, especially when saquinavir is first added.
- Your codeine dose may need to be adjusted and individualized by your care team until they see how you respond.
- If saquinavir is later stopped, watch for signs of opioid withdrawal, since your codeine effect could change again.
Tell your pharmacist or doctor right away if you feel unusually sleepy, confused, or short of breath.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Saquinavir together?
Saquinavir can raise codeine and morphine levels, increasing the risk of heavy sedation and slowed breathing. Keep taking both as prescribed, but ask your care team about monitoring or a codeine dose adjustment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Saquinavir interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Acetaminophen And Codeine and Saquinavir interaction managed?
You can usually take both, with care. Keep taking your medicines exactly as prescribed unless your care team tells you otherwise. Your team may monitor you more closely for excessive drowsiness or slowed breathing, especially when saquinavir is first added. Your codeine dose may need to be adjusted and individualized by your care team until they see how you respond. If saquinavir is later stopped,… Management is individual — always follow your own care team's guidance.
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 Acetaminophen And Codeine or Saquinavir 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)
- Product Information: Codeine sulfate oral solution, codeine sulfate oral solution. Hikma Pharmaceuticals USA Inc(per FDA), Berkeley Heights, NJ, 2023. DailyMed
- Product Information: Codeine sulfate oral tablets, codeine sulfate oral tablets. Hikma Pharmaceuticals USA Inc. (per FDA), Berkeley Heights, NJ, 2023. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Saquinavir
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