Oxycodone is roughly 1.5 times stronger than the hydrocodone in Vicodin, milligram for milligram. If you take 10 mg of each, oxycodone delivers about 50% more pain-relieving potency. That said, the real-world difference in pain relief is smaller than you might expect, and the two drugs work in similar ways on the same receptors in the brain.
How the Potency Difference Is Measured
Doctors compare opioid strength using a standard called morphine milligram equivalents (MME). Hydrocodone, the opioid in Vicodin, has a conversion factor of 1.0, meaning it’s considered equal to morphine in strength. Oxycodone has a conversion factor of 1.5. So 20 mg of hydrocodone per day equals 20 MME, while 20 mg of oxycodone per day equals 30 MME.
At the molecular level, oxycodone binds more tightly to the brain’s primary pain receptors. Lab measurements of binding affinity show oxycodone attaches to mu-opioid receptors about twice as readily as hydrocodone. That tighter binding is what translates into greater potency per milligram, though both drugs ultimately activate the same pain-relief pathway.
What Vicodin Actually Contains
Vicodin isn’t just an opioid. Each tablet combines hydrocodone with acetaminophen (the active ingredient in Tylenol). A standard Vicodin ES tablet, for example, contains 7.5 mg of hydrocodone and 750 mg of acetaminophen. The acetaminophen adds pain relief through a completely different mechanism, working on inflammation and pain signaling outside the opioid system.
Oxycodone is available both on its own and in combination products that also include acetaminophen (sold under brand names like Percocet). When people compare “Vicodin vs. oxycodone,” they’re often really comparing two combination products: hydrocodone plus acetaminophen versus oxycodone plus acetaminophen. In that case, both tablets include the acetaminophen boost, and the difference comes down to which opioid component is doing the heavier lifting.
The acetaminophen in these combination pills creates its own safety concern. More than 4,000 mg of acetaminophen in 24 hours raises the risk of serious liver damage, and people with liver conditions may need to stay well below that limit. If you’re taking multiple doses throughout the day, the acetaminophen adds up quickly.
Pain Relief in Practice
Despite oxycodone’s higher potency on paper, head-to-head clinical testing tells a more nuanced story. A large trial published in JAMA gave emergency department patients with acute limb pain either 5 mg oxycodone with acetaminophen or 5 mg hydrocodone with acetaminophen and measured pain scores two hours later. The oxycodone group reported a 4.4-point drop on a 10-point pain scale, while the hydrocodone group reported a 3.5-point drop.
That 0.9-point gap sounds meaningful, but the researchers had set 1.3 points as the minimum difference a patient would actually notice. The difference between the two drugs fell short of that threshold and wasn’t statistically significant. In other words, at the doses commonly prescribed for acute pain, most patients wouldn’t be able to tell which pill they took. The same trial also found that plain ibuprofen with acetaminophen performed just as well as either opioid, with a 4.3-point pain reduction.
This doesn’t mean the potency difference is irrelevant. Prescribers account for it when choosing doses. A patient who needs strong pain control might receive a lower milligram dose of oxycodone to achieve the same effect as a higher dose of hydrocodone. The drugs aren’t interchangeable at equal doses precisely because of the 1.5x potency gap.
Duration and How They Feel
Both immediate-release oxycodone and hydrocodone last about 3 to 6 hours per dose, so neither has a clear advantage in how long a single pill keeps working. Patients typically take either one every 4 to 6 hours as needed.
Side effects overlap heavily: nausea, constipation, drowsiness, and dizziness are common with both. Some people tolerate one better than the other for reasons that aren’t fully predictable. Oxycodone tends to cause slightly more nausea in some patients, while hydrocodone may be somewhat more sedating, though individual responses vary widely. If one causes bothersome side effects, switching to the other is a common clinical strategy.
DEA Scheduling and Abuse Potential
Both oxycodone and hydrocodone are classified as Schedule II controlled substances by the DEA, the most restrictive category for drugs that have accepted medical uses. This classification means both carry a high potential for abuse that can lead to severe physical or psychological dependence.
Hydrocodone wasn’t always in this category. Until 2014, hydrocodone combination products like Vicodin were classified as Schedule III, making them easier to prescribe with refills and phone-in orders. The reclassification to Schedule II reflected growing recognition that hydrocodone products carried the same addiction risks as other potent opioids. Today, both drugs require a new written prescription for each fill, with no refills allowed.
Why Potency Alone Doesn’t Determine Which Is “Better”
Stronger doesn’t automatically mean more effective or more appropriate. Prescribers choose between these two drugs based on the type and severity of pain, how a patient has responded to opioids before, other medications being taken, and liver and kidney function. The CDC’s current prescribing guidelines don’t recommend one over the other. Instead, they emphasize starting with the lowest effective dose of whichever opioid is chosen, using immediate-release formulations first, and maximizing non-opioid pain relief options before turning to opioids at all.
For a patient filling a prescription, the practical takeaway is straightforward: oxycodone packs more opioid punch per milligram, so doses are typically lower. But when dosed appropriately, both drugs can provide similar levels of pain control with similar durations of action and similar risk profiles.