Strongest to Weakest Opioids List

Medically Reviewed

Dozens of opioids are sold as prescription medications and illicit drugs in the United States. Abuse of both legal andillegal opioids can lead to severe substance use disorders and dangerous drug overdoses without treatment. Opioids are used to treat mild-to-moderate pain symptoms, but the opioid you are prescribed might depend on the nature or source of your pain.

Each opioid may also be sold in several different prescriptions. Some include only the opioid, while others might be mixed with other medications. Illicit opioids can be unpredictable, containing unknown adulterants and doses. Here are some of the most common opioids listed from strongest to weakest:


Fentanyl is the strongest opioid that’s commonly used to treat humans. It’s a synthetic opioid that’s chemically similar to morphine, but it’s about 50 to 100 times stronger. Fentanyl is used in epidurals for labor pain, transdermal patches for general analgesia, and lozenges for pain treatment in combat situations. Each of these routes of administration supplies a dose of fentanyl that’s smaller than a single milligram. Transdermal patches deliver about 12 mcg (micrograms) per hour, which has pain-relieving power that’s equal to around 30 mg (milligrams).


Heroin was once used for medicinal purposes in the United States, but now it’s used only as an illicit recreational drug. Second only to marijuana, it’s among the easiest-to-get illegal drugs in the country because of an influx of supply from transnational criminal organizations like the Mexican cartels. Pure heroin is about 50 times stronger than morphine. However, adulterants and additives make street heroin’s strength unpredictable. Fentanyl is often mixed into heroin, which can increase its potency to dangerous levels.


Oxycodone is a prescription opioid that’s sold in medications under the brand names OxyContin and Percocet. In the United States, it is a common opioid pain reliever that’s used to treat moderate-to-severe pain. The drug is about 1.5 times the strength of morphine’s analgesic ability. It also has a high addiction liability and can cause substance use problems when it’s abused or taken for too long.


Morphine is a naturally occurring opioid and one of the first opioids ever to be isolated. It’s sold under brand names like Kadian and Avinza, and it’s one of the oldest and most widely used opioids in the world. Morphine is very similar to a natural chemical in your brain called endorphins. In fact, endorphins get their name by combining the words “endogenous morphine.” Morphine can be effective in adults at doses of 10 mg; 30 mg is considered a high dose. Doses between 60 to 200 mg can be dangerous or fatal. Morphine is also highly addictive if it’s abused or taken too long.



Codeine, one of the most commonly used opioids, is found in a variety of medications all over the world. It’s also one of the longest-used opioid medications, having been discovered in 1832. It’s the weakest of the four most common opioids, and it’s used to treat moderate pain and mild irritations like coughs and diarrhea.

However, with a significant dependence liability, it’s not commonly used to treat mild symptoms in the United States. On its own, the drug is considered a Schedule II drug in the U.S., which means it has some medical uses, but it also has a high likelihood of abuse. Codeine is effective in 15 to 60 mg for adults. A lethal dose may be somewhere around 500 mg or more.

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