Comparison Table

The following table provides an educational overview of commonly prescribed opioid medications:

Property Oxycodone Hydrocodone Morphine Tramadol Codeine
DEA Schedule Schedule II Schedule II Schedule II Schedule IV Schedule III (combination)
Relative Potency (vs. Morphine) 1.5–2x ~1x 1x (reference) 0.1–0.2x 0.1–0.15x
Duration of Action 3–4 hours (IR) 4–6 hours 3–4 hours (IR) 4–6 hours 4–6 hours
Common Dose Range 5–15 mg q4–6h 5–10 mg q4–6h 15–30 mg q4h 50–100 mg q4–6h 15–60 mg q4–6h
Primary Formulations IR, ER (OxyContin) IR, ER (Hysingla, Zohydro) IR, ER (MS Contin), injectable IR (Ultram) IR, combination products
Common Brand Names OxyContin, Percocet (combo) Vicodin, Norco (combo) MS Contin, Kadian, MorphaBond Ultram, ConZip Tylenol with Codeine
Active Metabolites Yes (minor) Yes (hydromorphone) Active (morphine-6-glucuronide) Yes (O-desmethyltramadol) Yes (morphine)
Special Considerations High abuse potential; ER formulation tamper-resistant Most commonly prescribed opioid in U.S. Gold standard for opioid comparison; available IV Lower abuse potential; seizure risk; serotonin syndrome risk Prodrug (converted to morphine); poor metabolizers get no benefit

Individual Medication Profiles

Oxycodone

A semi-synthetic opioid approximately 1.5–2 times as potent as morphine. Available in immediate-release (IR) and extended-release (ER, OxyContin) formulations. The combination product Percocet (oxycodone + acetaminophen) is one of the most commonly prescribed pain medications. The ER formulation is tamper-resistant to deter abuse.

Hydrocodone

A semi-synthetic opioid approximately equianalgesic to morphine. The most commonly prescribed opioid in the United States. Historically available only in combination products (Vicodin, Norco with acetaminophen), ER-only formulations (Hysingla, Zohydro) are now available. Metabolized partially to hydromorphone.

Morphine

The reference opioid against which all others are compared. Available in oral (IR and ER), injectable, and transdermal forms. Active metabolite (morphine-6-glucuronide) accumulates in kidney impairment, requiring dose adjustment. Considered the gold standard for opioid equianalgesic conversions.

Tramadol

A centrally-acting opioid with weaker binding to mu-opioid receptors (approximately 1/10th the potency of morphine). Also inhibits serotonin and norepinephrine reuptake. Lower abuse potential than other opioids, but still carries risk. Unique risks include seizure (especially at higher doses) and serotonin syndrome when combined with other serotonergic medications. Schedule IV, making it the least-restricted opioid on this list.

Codeine

A prodrug that must be converted to morphine by the CYP2D6 enzyme to provide pain relief. This makes its effectiveness highly variable: poor CYP2D6 metabolizers get little to no pain relief, while ultra-rapid metabolizers may experience toxicity. Most commonly prescribed in combination products (Tylenol with Codeine). FDA has restricted codeine use in children under 12 due to safety concerns.

Understanding Equianalgesic Dosing

Equianalgesic dosing refers to converting between opioids to achieve equivalent pain relief. This is important when switching from one opioid to another. The approximate equianalgesic oral doses (equivalent to 30 mg oral morphine) are:

  • Morphine 30 mg oral = reference dose
  • Oxycodone 20 mg oral
  • Hydrocodone 30 mg oral
  • Tramadol 150–300 mg oral
  • Codeine 200 mg oral

Note: Equianalgesic conversions must be performed by a qualified healthcare provider. Cross-tolerance is incomplete, and dose reductions of 25–50% are typically applied when converting between opioids to account for incomplete cross-tolerance.

Risks and Considerations

  • Respiratory depression: The most serious acute risk. Dose-dependent; risk increases with higher doses, concurrent CNS depressants, and in patients with sleep apnea or COPD.
  • Dependence and withdrawal: Physical dependence can develop within days to weeks. Withdrawal symptoms include anxiety, muscle aches, insomnia, nausea, and diarrhea.
  • Tolerance: The need for higher doses to achieve the same effect. Develops more rapidly to some effects (analgesia) than others (respiratory depression).
  • Opioid-induced constipation: Occurs in virtually all patients on long-term opioids. Prophylactic bowel regimen is recommended.
  • Opioid-induced hyperalgesia: Paradoxical increased pain sensitivity with long-term opioid use.
  • QT prolongation: Methadone (not on this table) and high-dose tramadol can prolong the QT interval.

Resources

Important: This comparison is for educational purposes only and does not constitute a recommendation for any specific medication. Opioid selection depends on individual patient factors including pain severity, medical history, kidney and liver function, other medications, and risk factors. Opioid therapy should only be prescribed and managed by a certified clinician following a thorough risk-benefit assessment.