Understanding Opioid Strengths and Other Prescribing Pearls

Whether or not you prescribe opioids, a lot of your patients are taking them. So, it’s important for nurse practitioners and physician assistants to get familiar with how they work to guide your treatment and prescribing plans. Today, let’s talk opioid strengths. When we talk about the ‘strength’ of opioid medications, there are two aspects to consider. First, we look at the drug potency. Second, we can look at the drug’s duration of action. For the purposes of today’s post, we will discuss potency. 

The key to assessing an opioid medication’s potency is to remember morphine. Morphine is basically the standard opioid and the drug we measure all opioids against. We reference how ‘strong’ or potent an opioid is, we talk about it in “morphine milligram equivalents” If you’re switching your patient between opioid medications, for example, you’ll want to convert to morphine milligram equivalents (MME) to make sure you aren’t providing too much or too little pain opioid. The CDC has a helpful chart that outlines the process here

Overall, here’s a rundown of the opioids you’re most likely to see listed from most to least potent with a few prescribing notes. 

1. Fentanyl

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Brand names: Duragesic, Abstral, Actiq, Fentora and others

Route: IV/IM, Transdermal, Intranasal, Buccal 

Fentanyl is a crazy strong opioid, about 50 to 100 times stronger than morphine. In practice, Fentanyl is most commonly seen in the surgical setting or for severe (think cancer) pain. One benefit of the drug over other opioids is that Fentanyl has a short duration of action. So, although it has the side effect of respiratory depression like other meds on this list, it wears off quickly. This profile makes it particularly popular for use in surgeries. Given Fentanyl’s super-high potency, Fentanyl patches are contraindicated in opioid naive patients (the IV formulation is not as it wears off quickly). Finally, Fentanyl is a synthetic opioid so it’s less likely to cause a histamine-mediated reaction (rash/itching) in certain patients than non-synthetic opioid options.

2. Hydromorphone

Brand names: Dilauded, Exalgo 

Route: IV/IM, PO, Rectal Suppository 

Hydromorphone is about 4 times more potent than morphine and is commonly found in the hospital setting. It has a high addiction potential and is often used as a substitute for heroin by addicts for its rapid onset. Hydromorphone is a synthetic opioid so is less likely to cause a histamine-mediated reaction (rash/itching) in certian patients than other opioid options.

3. Oxymorphone

Brand names: Opana, Numorphan

Route: PO, Rectal Suppository

Oxymorphone is about 3 times more potent than morphine. Oxymorphone is highly addictive, so much so that in 2017, the FDA asked the manufacturer to remove Opana ER from the market. The extended release formulation was pulled by Endo Pharmaceuticals although generic versions of oxymorphone extended release remain available. It is also a synthetic opioid so is less likely to cause a histamine-mediated reaction (rash/itching) in certain patients than some other opioid options.

4. Methadone

Brand names: Methadone, Dolophine, Methadose

Route: PO, IM/IV, SQ

Originally created by the Germans during WWII for treatment of pain, Methadone is now prescribed for treatment of addiction and withdrawal and is taken under strict medical supervision. While it seems counterintuitive to treat opioid addiction with…an opioid, with its long half-life, methadone fits the bill. Highly addictive and highly regulated, methadone comes with a lot of paperwork and requires that users go to designated methadone clinics for treatment.

5. Oxycodone

Brand names: Perccet, OxyContin, Roxycodone, Percodan, Oxycodan, Tylox

Route: PO

Oxycodone is about 1.5 times stronger than morphine and is used for relief of moderate to severe pain. It is commonly formulated with acetaminophen, and occasionally with other pain relievers like aspirin or ibuprofen to increase analgesic effects. There are a number of oxycodone combination medications on the market. Oxycodone is commonly abused and sold as a street drug. Oxycodone is only approved for oral use in the U.S. although IM/IV formulations are found in other countries. 

6. Morphine

Brand names: Kadian, MS Contin, Durmorph, DepoDur, Infumorph, Morphabond

Route: PO, IV/IM, SQ, Rectal Suppository

Again, Morphine sets the standard for opioid potency calculations. Its the reference point by which we measure the strength of other opioid medications. Morphine is available in both immediate and sustained release formations so it may be prescribed for chronic or breakthrough/acute pain relief. As with other opioids, prescribe with caution in patients with renal insufficiency/kidney failure. 

7. Hydrocodone

Brand names: Vicodin, Lortab, Lorcet, Norco

Route: PO 

Hydrocodone and morphine’s potency are pretty close to equivalent. Commonly formulated with acetaminophen and occasionally with ibuprofen, there are a number of combination hydrocodone formulations on the market. Hydrocodone is also found in cough suppressing medications. 

8. Codeine

Brand names: Tylenol-Codeine, Codeine Sulfate 

Route: PO 

Codeine is relatively low potency on the opioid scale. Often used in cough suppressing formulations, codeine can also be used to treat pain. Codeine is commonly combined with acetaminophen increase its efficacy. Once codeine is ingested, the body metabolizes the drug to morphine where it binds to opioid receptors in the brain. Some people known as codeine ‘ultra metabolizers‘ (about 5 percent of the population) experience this morphine conversion reaction more rapidly than the rest of the population and can experience symptoms of overdose (including severe respiratory depression) by taking standard doses of codeine. In contrast, about 8 percent of the population is unable to metabolize codeine to morphine and therefore has a sub-therapeutic response to the drug. 

9. Meperidine

Brand names: Demerol, Mepergan (combination with promethazine) 

Route: PO, IV/IM, S

Meperidine was the first synthetic opioid to hit the market but in recent years has fallen out of favor. Meperidine has a significant side effect profile and can cause seizures and neurotoxicity. Although it is not nearly as potent as some other opioids on this list, Meperidine also has a high abuse potential, quickly causing physical dependence among users. Current guidelines recommend that clinicians reserve meperidine use for short procedures. 

10. Tramadol

Brand names: Ultram, Ultracet, 

Route: PO

While Tramadol is among the lowest potency opioids, it is still addictive. Tramadol works a bit differently than other medications on this list in that it has some opioid-like properties and some tricyclic antidepressant-like properties. Until recently, tramadol was not considered a controlled substance, but a few years ago was added to the list of scheduled medications. Use caution when prescribing tramadol to patients taking SSRIs as the combination of the two drugs can cause serotonin syndrome. 


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