Equianalgesic Conversion: How to Safely Switch Between Pain Medications

When you need to switch from one pain medication to another, equianalgesic conversion, the process of matching the pain-relieving strength of one drug to another. Also known as opioid conversion, it’s not just math—it’s a safety step that can prevent overdose, withdrawal, or uncontrolled pain. Get this wrong, and you could end up in the hospital. Get it right, and you keep managing pain without unnecessary risk.

Doctors use morphine equivalent, a standard unit that measures how strong a pain drug is compared to morphine to compare everything from oxycodone to fentanyl patches. But here’s the catch: these numbers aren’t exact for everyone. Your age, liver function, kidney health, and how long you’ve been on opioids all change how your body handles the switch. That’s why a 10mg oxycodone isn’t always equal to 15mg morphine in real life. And if you’re switching from a long-acting drug like methadone to a short-acting one? The math gets even trickier. Methadone sticks around for days, so even if the numbers look right on paper, you could still overdose if you don’t wait long enough between doses.

analgesic equivalence, the principle that different drugs can provide the same level of pain relief at specific doses sounds simple, but it’s full of traps. For example, switching from hydrocodone to hydromorphone? The ratio is 5:1, but if you’re elderly or have liver damage, that ratio could be way off. Even over-the-counter painkillers like acetaminophen and NSAIDs can interfere with how opioids work, making the whole conversion less predictable. And don’t forget about drug interactions—meds for anxiety, sleep, or heart conditions can make opioid side effects worse. That’s why every conversion needs to be personalized, not pulled from a chart.

The posts below show real cases where equianalgesic conversion went right—and wrong. You’ll find guides on how to handle transitions between opioids, why some drugs need extra monitoring, and how conditions like liver disease or heart failure change the rules. There’s also advice on spotting when a conversion might be too aggressive, what signs to watch for after switching, and how to talk to your provider about dosage changes. No theory. No guesswork. Just what works when you’re trying to stay safe and in control of your pain.