Dilaudid (hydromorphone) is roughly three to four times stronger than OxyContin (oxycodone) on a milligram-for-milligram basis. A standard equianalgesic table from the National Institutes of Health puts 8 mg of oral hydromorphone as equivalent to 20–30 mg of oral oxycodone, meaning you need far less Dilaudid to achieve the same level of pain relief.
How the Potency Numbers Compare
The most common way to compare opioid strength is by converting each drug to its oral morphine equivalent, or OME. UCSF’s pain management program assigns hydromorphone a multiplication factor of 5, meaning each milligram equals 5 mg of morphine. Oxycodone gets a factor of 1.5, so each milligram equals 1.5 mg of morphine. By that math, 1 mg of Dilaudid delivers roughly the same pain relief as 3.3 mg of OxyContin.
These conversion ratios are approximations. Published equianalgesic tables vary, and most are built on clinical consensus rather than tightly controlled trials. In practice, your body’s response to a given opioid depends on genetics, tolerance, kidney function, and other medications you’re taking. Still, every widely used conversion table agrees on the core point: hydromorphone is significantly more potent per milligram than oxycodone.
Why Dilaudid Is More Potent
Both drugs work by activating the same target in the brain, the mu-opioid receptor, which controls pain signaling. The difference comes down to how tightly each molecule binds to that receptor. Research ranking opioid binding strength places hydromorphone in the highest-affinity category (below 1 nanomolar), alongside drugs like fentanyl and oxymorphone. Oxycodone falls into a moderate-affinity group, binding roughly 10 to 100 times less tightly. Because hydromorphone latches onto the receptor more efficiently, a smaller dose produces the same analgesic effect.
OxyContin vs. Dilaudid in Practice
Despite the potency gap, “stronger” doesn’t automatically mean “better at treating pain.” A large head-to-head trial called EXHEAL compared extended-release hydromorphone with extended-release oxycodone in cancer patients and found equivalent pain relief and similar rates of side effects when doses were properly adjusted. The real-world difference lies in when and why each drug gets prescribed.
OxyContin is an extended-release formulation of oxycodone designed to provide steady pain control over 12 hours. It reaches peak levels in about an hour and achieves stable blood concentrations within 24 to 36 hours of regular dosing. It’s used for both chronic non-cancer pain and cancer pain when around-the-clock relief is needed.
Dilaudid, in its standard form, is an immediate-release tablet or injection. Its higher potency makes it a second-line option, typically reserved for situations where other opioids haven’t provided adequate relief or where a patient already tolerates opioids and needs a more concentrated dose. The injectable, high-potency version is specifically intended for opioid-tolerant patients who require large doses to manage severe pain.
Higher Potency Means Higher Risk
Both hydromorphone and oxycodone are classified as Schedule II controlled substances by the DEA, the most restrictive category for drugs that have accepted medical uses. Schedule II means a high potential for abuse that can lead to severe physical or psychological dependence. But Dilaudid’s greater potency per milligram creates a narrower margin for error. A small miscalculation in dose carries more consequence when each milligram is three to four times as powerful.
This is one reason CDC guidelines recommend starting opioid-naive patients on immediate-release formulations at the lowest effective dose, regardless of which opioid is chosen. For someone who has never taken opioids before, clinicians generally begin with a less potent option like oxycodone rather than jumping to hydromorphone. Dilaudid enters the picture when lower-potency drugs aren’t enough.
Side Effects Are Similar
Because both drugs activate the same receptor, they share the same core side effects: nausea, constipation, drowsiness, slowed breathing, and itching. The EXHEAL trial confirmed that adverse event rates were comparable between the two when doses were adjusted for equivalent pain relief. The critical distinction isn’t that one drug causes worse side effects than the other. It’s that Dilaudid reaches the threshold for dangerous respiratory depression at a lower milligram dose simply because each milligram does more.
What the Potency Difference Means for You
If you’re comparing these two drugs because you’ve been prescribed one or are being switched to the other, the key takeaway is that doses are not interchangeable milligram for milligram. Switching from 20 mg of OxyContin to 20 mg of Dilaudid would be a dangerous overdose. Equianalgesic tables exist precisely for this reason, and clinicians typically reduce the calculated equivalent dose by 25–50% when switching between opioids to account for incomplete cross-tolerance, meaning the relief you built up to one opioid doesn’t fully carry over to another.
If you’re comparing them out of general curiosity, the simplest summary is this: Dilaudid is the more powerful drug per milligram, but when dosed correctly, both provide similar pain relief with similar side effects. Potency is a pharmacological measurement, not a ranking of which drug “works better.” The right choice depends on the type of pain, how long relief needs to last, and what a patient has already tried.