Cilostazol and Acetaminophen And Codeine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jun 30, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Cilostazol
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.
Your pain medicine has two parts: acetaminophen (like Tylenol) and codeine, an opioid. Cilostazol (Pletal) can slow down one of the liver enzymes that helps process codeine. When that happens, more codeine and its active form (morphine) can build up in your body.
That could make the opioid effects stronger, like extra drowsiness, or in serious cases slowed breathing. This is based mostly on theory, not lots of real-world reports, so try not to worry. Just watch for feeling unusually sleepy or slow breathing, and let your doctor or pharmacist know you take both. Your care team can manage this safely.
Effect: Cilostazol, a CYP3A4 inhibitor, may reduce CYP3A4-mediated codeine metabolism, increasing codeine and morphine exposure. Note codeine is a prodrug (activated primarily via CYP2D6 to morphine); the CYP3A4 pathway is a secondary route, so accumulation of parent codeine and shunting can raise opioid effect.
- Direction: increased opioid exposure / effect
- Risk: sedation, respiratory depression, potentially fatal
- Evidence: theoretical; magnitude/onset unspecified
- Management: monitor for sedation and respiratory depression; consider codeine dose reduction until stable effects seen. If cilostazol is discontinued, monitor for opioid withdrawal and consider dose increase.
What happens
Increased codeine and morphine exposure
Interaction Deep Dive
Concomitant use of codeine with CYP3A4 inhibitors has resulted in increased codeine and morphine concentrations, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression, particularly when an inhibitor is added after a stable dose of codeine is achieved. If concomitant use is needed, closely monitor patients for respiratory depression and sedation, and consider dose reduction of codeine until stable drug effects have been observed. If a CYP3A4 inhibitor is being discontinued, monitor patients for signs of opioid withdrawal, and consider increasing dose of codeine until stable drug effects have been observed12.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated codeine metabolism
How to manage this interaction
Keep taking both medications as prescribed unless your prescriber tells you otherwise. This concern is theoretical, but it is worth managing carefully.
- Your care team may monitor you more closely for excess sedation or slowed breathing, especially soon after cilostazol is started.
- Your codeine dose may be adjusted and individualized by your team until your response is stable.
- If cilostazol is stopped, they may watch for withdrawal signs and adjust accordingly.
- Call right away if you feel very drowsy, confused, or notice slow or shallow breathing.
Ask your pharmacist or doctor before making any change.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Cilostazol and Acetaminophen And Codeine together?
Cilostazol can raise codeine and morphine levels, so watch for extra drowsiness or slowed breathing and tell your care team you take both; they can adjust the dose and monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cilostazol and Acetaminophen And Codeine 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 Cilostazol and Acetaminophen And Codeine interaction managed?
Keep taking both medications as prescribed unless your prescriber tells you otherwise. This concern is theoretical, but it is worth managing carefully. Your care team may monitor you more closely for excess sedation or slowed breathing, especially soon after cilostazol is started. Your codeine dose may be adjusted and individualized by your team until your response is stable. If cilostazol is stop… 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 Cilostazol or Acetaminophen And Codeine 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 Cilostazol
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