What the FDA labels say about taking them together
Codeine and fluoxetine
Codeine's FDA label of December 22, 2025 names fluoxetine in its drug interactions section; fluoxetine's label does not name codeine itself but warns about its class (Opioids (opioid agonists)). The codeine label: “Codeine is metabolized by CYP2D6 to form morphine. The concomitant use of Codeine Sulfate Tablets and CYP2D6 inhibitors can increase the plasma concentration of codeine, but can decrease the plasma concentration of …”
Check it at the source: the codeine FDA label on DailyMed (effective December 22, 2025, Hikma Pharmaceuticals USA Inc.); the fluoxetine FDA label on DailyMed (effective January 8, 2026, Dista Products Company).
What does the codeine label say about fluoxetine?
Codeine label, drug interactionsRifampin, carbamazepine, phenytoin Inhibitors of CYP2D6 Clinical Impact: Codeine is metabolized by CYP2D6 to form morphine. The concomitant use of Codeine Sulfate Tablets and CYP2D6 inhibitors can increase the plasma concentration of codeine, but can decrease the plasma concentration of active metabolite morphine, which could result in reduced analgesic efficacy or symptoms of opioid withdrawal … patients at frequent intervals for signs and symptoms of respiratory depression or sedation. Paroxetine, fluoxetine, bupropion, quinidine.
Source: FDA drug label (Codeine sulfate), Hikma Pharmaceuticals USA Inc., effective December 22, 2025 (SPL set 010905f9-3bcb-4b50-9fe8-a3ad0010f14c), via openFDA; the full label on DailyMed
What does the fluoxetine label say about codeine?
Fluoxetine's label does not name codeine itself; it warns about its class (Opioids (opioid agonists)):
Fluoxetine label, drug interactionsThe concomitant use of serotonergic drugs (including other SSRIs, SNRIs, triptans, tricyclic antidepressants, opioids, lithium, buspirone, amphetamines, tryptophan, and St. John's Wort) with PROZAC increases the risk of serotonin syndrome.
Source: FDA drug label (Prozac), NDA018936 (Eli Lilly And Co), as published by Dista Products Company, effective January 8, 2026 (SPL set c88f33ed-6dfb-4c5e-bc01-d8e36dd97299), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Codeine | Fluoxetine | |
|---|---|---|
| Labeled for | Pain | Depression, Anxiety, Bipolar disorder |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.726 per tablet 30 mg tablet | $0.0519 per capsule 40 mg capsule |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once