Types of Opioids & Their Strengths: Heroin, Fentanyl, Morphine & More

What Are Opioids?

Opioids are a class of painkillers that interact with a person’s opioid receptors, reducing pain and giving a person a sense of euphoria. Included in this class of drugs are several illegal drugs with no or very few accepted medical uses, such as heroin, as well as prescription medications that are commonly used to help patients manage pain, such as oxycodone and morphine.

A term related to opioid and often incorrectly used interchangeably is opiate. While the term opioid can refer to any opioid, opiate specifically refers to natural opioids. Synthetic and semisynthetic opioids, such as fentanyl, are not opiates. In other words, all opiates are opioids, but not all opioids are opiates.

These are some of the many opioids:

• Benzhydrocodone
• Buprenorphine
• Carfentanil
• Codeine
• Fentanyl
• Heroin
• Hydrocodone
• Hydromorphone (Dilaudid)
• Levorphanol tartrate
• Methadone
• Morphine
• Opium
• Oxycodone
• Oxymorphone
• Percocet
• Pethidine
• Sufentanil
• Tapentadol
• Tramadol

Long-Acting Opioids

When discussing opioids, it is helpful to further break down these medications by how long they remain in the body. Opioids that last a long time in the body are called long-acting opioids. They may also be referred to as extended-release or controlled-release opioids.

These are common long-acting opioids:

Morphine (Controlled-Release & Extended-Release)

Morphine comes in many forms. It is often used as the “standard” to compare other opioids to in terms of strength and risk.

Controlled-release (Kadian) and extended-release (Avinza) morphine are similar in many ways. Controlled-release capsules are typically taken at a starting dose of 20 mg every 12 or 24 hours, and extended-release capsules are taken at a dose of 30 mg once a day.

Oxycodone (Controlled-Release)

Controlled-release oxycodone, sold under the name OxyContin, is a long-acting opioid that doctors often consider a secondary treatment option. The risk that the drug may be diverted and misused is higher than with many other opioids in this category, including morphine.

Oxycodone generally comes in 10, 20, 40, and 80 mg strengths. Patients typically start at 10 mg every 12 hours. 

Oxymorphone (Extended-Release)

This kind of oxymorphone, sold as Opana ER, comes in 5, 10, 20, 30, and 40 mg strengths. Patients typically start at 5 mg every 12 hours. 

Hydromorphone (Extended-Release)

Sold as Exalgo ER, this medication comes in 8, 12, and 16 mg strengths, with patients typically starting on a dose of 8 mg daily.

Methadone

Methadone is an opioid that is often used to treat opioid use disorder, which may seem paradoxical at first. However, by administering methadone in a controlled setting, doctors can help a patient reduce their cravings and make it easier to resist misusing drugs.

Over time, a person’s methadone dose can be reduced, slowly weaning them off opioids in a safe and controlled way that reduces the withdrawal symptoms they would normally experience. However, methadone can also be abused if not used as prescribed.

Fentanyl (Transdermal Implant)

Fentanyl is a powerful opioid, tens of times stronger than morphine, but it is difficult to misuse when administered via a transdermal implant. The patches come in strengths of 25, 50, 75, and 100 mcg/hr, with patients typically starting at a dose of 25 mcg applied every 3 days. The patches are sold under the name Duragesic. 

Buprenorphine (Transdermal Implant)

Buprenorphine is an unusual opioid in that it has a ceiling effect, where a person doesn’t feel a continually stronger effect the more one uses. With that said, it still does have some abuse potential, although the transdermal implant option is difficult to abuse, much like the fentanyl implant.

Buprenorphine is commonly used to treat opioid use disorder — both on its own and in combination medications like Suboxone (buprenorphine/naloxone).

Sold as Butrans, the patches come in strengths of 5, 10, and 20 mcg/hr, with the starting dose and dosing interval typically at 5 mcg applied every 7 days.

Short-Acting Opioids

Short-acting opioids last a shorter time in the body and typically cause a more intense effect in the user. For this reason, they are typically considered to have higher abuse potential, although some studies refute this idea.

Both types of opioids have significant abuse potential if misused. One issue with the differentiation when considering the risk of each is that long-acting opioids can sometimes be tampered with to convert them into short-acting opioids.

Common short-acting opioids include the following:

Dihydrocodeine

Dihydrocodeine is a semisynthetic opioid, meaning it is created with a process that begins with compounds from natural sources that are further synthesized into a different drug. It has a duration of action lasting between 3 and 6 hours. It is significantly less potent than morphine.

Pethidine

Pethidine has a duration of action that lasts between 2 to 4 hours. It is only slightly more potent than dihydrocodeine.

Hydrocodone

Hydrocodone has a duration of action that lasts 4 to 8 hours. It is about two-thirds as potent as morphine. 

Oxycodone

Oxycodone is slightly more potent than morphine, with a duration of action lasting about 3 to 4 hours.

Hydromorphone

Hydromorphone is an opioid that is significantly more potent than morphine, with manufacturers recommending one consider it 5 to 7.5 times more potent as morphine. Its effects last about 4 to 5 hours.

Buprenorphine 

Short-acting buprenorphine acts similarly to its long-acting counterpart, with a similar ceiling effect. While technically more potent than morphine by a significant degree, it has a much lower abuse and harm potential in practical terms.

Heroin

Heroin is one of the most notorious opioids, known (correctly) as an addictive and dangerous drug that is more potent than morphine.

Because it is generally produced illegally, it is also very common for heroin to be mixed with other substances. These mixtures can make the drug’s effect unreliable for a user, with varying strength, addictiveness, and danger depending on what a dealer has cut the heroin with.

Fentanyl

Short-acting fentanyl is a potent, dangerous drug with high abuse and addiction potential. It can be as much as 100 times stronger than morphine, and it can easily be deadly to a first-time user who underestimates its strength.

Fentanyl is frequently mixed with heroin, which a dealer may not inform a buyer about. 

Understanding the Strength of Opioids

Again, the strength of opioids varies. Morphine is a fairly strong opioid with abuse potential. It is carefully controlled, but it is overall middling in strength compared to many other opioids.

For context, morphine is over 200 times stronger than ibuprofen in terms of pain relief. However, remember that ibuprofen isn’t an opioid.

Comparable Opioids

Some opioids with comparable strength to morphine include hydrocodone, oxycodone, and codeine. Hydrocodone is about as strong as morphine, and oxycodone is about 50 percent stronger. Codeine is about three times as potent, which is significant but much less than some of the drugs we discuss below. 

Strongest Opioids

Heroin, buprenorphine, and fentanyl are all significantly stronger than morphine, but that grouping of drugs is somewhat misleading. Because of its ceiling effect, buprenorphine is not really comparable to heroin and fentanyl, and it often plays a key role as part of an opioid addiction treatment program.

Unfortunately, those other two drugs are commonly misused. Many people imagine heroin when they think of highly addictive, potent opioids being sold and used on the street, but fentanyl is significantly more potent and sometimes mixed in with heroin to make it more addictive.

One of the single strongest opioids with any kind of legitimate use is carfentanil, which is about 10,000 times stronger than morphine and extremely dangerous to humans in essentially any dose. It is used as a painkiller for very large animals, such as elephants. Sometimes, carfentanil is mixed with heroin and sold on the streets, resulting in an extremely potent, dangerous street drug.

Opioid Facts & Statistics to Consider

In 2017, over 191 million opioid prescriptions were dispensed to Americans, with Alabama having the highest prescription rate in the country and Hawaii having the lowest. While many of these prescriptions were likely legitimate and most were well-intentioned, the high rate of opioid prescription is in part responsible for the opioid epidemic in the country.

Over 11.5 million Americans reported misusing prescription opioids in 2016 at least once.

Of the prescription medications that are involved in opioid overdose deaths, methadone, oxycodone, and hydrocodone are the most common.

Overdose deaths can involve only a single opioid medication, but they are often the result of a person mixing other substances with opioids, such as alcohol. Some of the most dangerous medications to take with opioids are benzodiazepines, or benzos, a type of sedative that affects many of the same systems opioids affect.

Unfortunately, the opioid epidemic is not under control, even as awareness of the issue spreads among medical practitioners. A steady rise in opioid deaths can be seen over time following a pattern of three waves:

• Wave 1 — 1999: The initial rise in opioid overdose deaths
• Wave 2 — 2010: The beginning of a spike in heroin overdose deaths
• Wave 3 — 2013: The beginning of a spike in synthetic overdose deaths, which continues to trend upward as of 2022

Opioid Potency 

The following is a chart for easy reference regarding the potency of several of the most commonly misused opioids and how they compare in potency to morphine. The two opioids in bold, heroin and carfentanil, have essentially no medical use for humans (although heroin was originally designed for medical purposes).

Drug	Potency Compared to Morphine
Morphine	1/1
Codeine dihydrocodeine	1/10
Pethidine	1/8
Hydrocodone	2/3
Oxycodone	1.5/1
Heroin	2-5/1, with heroin frequently mixed with other substances that may make it more addictive, potent, and/or dangerous
Methadone	Approximately 5-10/1, although with significantly different properties that require care from the prescriber to safely dose it out
Buprenorphine	Approximately 80/1, with the ceiling effect discussed earlier greatly reducing abuse potential
Fentanyl	100/1
Carfentanil	10,000/1, making it extremely dangerous for human use