Although Dilaudid and fentanyl are both powerful pain relievers, they have many differences, such as their strength, onset and duration, and more.

If you have severe pain, Dilaudid (the brand name for hydromorphone) and fentanyl are two options your doctor may consider for your treatment. Both Dilaudid and fentanyl are highly potent opioids. However, they have some key differences you should keep in mind if you have been prescribed one of the drugs.

What Is Fentanyl?

Fentanyl is a Schedule II controlled substance and an opioid for severe pain. It is a synthetic opioid, meaning it is man-made in a lab. It is sold under a variety of brand names, including:

  • Abstral
  • Actiq
  • Duragesic
  • Fentora
  • Lazanda
  • Sublimaze
  • Subsys

What Is Dilaudid?

Like fentanyl, Dilaudid is an opioid and a Schedule II controlled substance. Dilaudid is the brand name of the generic drug hydromorphone. It is a semi-synthetic opioid, meaning that it is partially derived from natural opium sources and partially made in a lab. 

Dilaudid vs. Fentanyl: Similarities & Differences

Although both Dilaudid and fentanyl are opioids used to treat severe pain, they have many differences. This includes their relative strength, available doses and dosage forms, how long they last and their side effects. If you are switching from one drug to the other, it is important to know what to expect based on the drugs’ similarities and differences.


Fentanyl is not only stronger than hydromorphone, but it is also the strongest available pain medication. Pain medication strength is generally compared to morphine. While hydromorphone is four times stronger than morphine, fentanyl is 50 to 100 times stronger than morphine. 

Fentanyl is so strong that Duragesic, the skin patch formulation of fentanyl, differs from most other opioids in that it should not be used by someone who is not used to taking opioids. Doing so can increase the risk of overdose.


Because fentanyl is so strong, its doses are generally much smaller than doses of other opioids, including hydromorphone, on the order of micrograms (mcg) for fentanyl compared to milligrams (mg) for hydromorphone. Other than hospital-only injectable dosage forms, both agents are available in pharmacies in a variety of dosage forms and doses for outpatient use:

Hydromorphone dosage forms and doses:

Oral solution5 mg per mL
Short-acting tablets2 mg, 4 mg, 8 mg
Long-acting tablets8 mg, 12 mg, 16 mg, 32 mg

Fentanyl dosage forms and doses:

Skin patch12.5 mcg/hour, 25 mcg/hour, 50 mcg/hour, 75 mcg/hour, 100 mcg/hour
Sublingual liquid100 mcg, 200 mcg, 400 mcg, 600 mcg, 800 mcg, 1,200 mcg, 1,600 mcg
Buccal lozenge200 mcg, 400 mcg, 600 mcg, 800 mcg, 1200 mcg, 1600 mcg
Tablet100 mcg, 200 mcg, 400 mcg, 600 mcg, 800 mcg
Nasal solution100 mcg, 300 mcg, 400 mcg
Sublingual tablet100 mcg, 200 mcg, 300 mcg, 400 mcg, 600 mcg, 800 mcg

Onset & Duration

Fentanyl starts working quickly, within about 10 minutes. While the buccal and sublingual dosage forms generally last for a few hours at a time, the skin patch is left on the skin for a full 72 hours and works to fight pain the whole time it is on the skin.

In contrast, hydromorphone starts working within 15 to 30 minutes and lasts between four and five hours.

Side Effects

Because they are both opioids, fentanyl and hydromorphone have similar side effects to each other and to other opioids. These include:

  • Relaxation
  • Drowsiness
  • Euphoria
  • Dizziness
  • Pain relief
  • Sedation
  • Confusion
  • Nausea or vomiting
  • Slow urination
  • Small pupils
  • Slowed breathing

Addiction Potential

Both Dilaudid and fentanyl are Schedule II controlled substances, meaning they have a high potential for abuse, dependence and addiction. Addiction potential does not go away with time, meaning that long-term abuse increases the risk of addiction. In addition, long-term abuse can increase the risk of complications like:

  • Constipation
  • Sleep apnea
  • Fractures
  • Hormonal abnormalities

Find Help for Opioid Addiction in New Jersey

Opioid addiction is the main driver of opioid overdose deaths in the United States, with almost 75% of overdose deaths in 2020 from opioids. In New Jersey alone, prescription opioids like Dilaudid and fentanyl caused 457 deaths in 2020. Opioid addiction is hard to overcome, but help is available. The Recovery Village Cherry Hill at Cooper offers a full continuum of care as you recover from opioids, starting with medical detox and staying at your side through rehab and aftercare. Don’t wait: contact us today to see how we can help.

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Editor – Abby Doty
Abby Doty graduated from Hamline University in 2021 with a Bachelor's in English and Psychology. She has written and edited creative and literary work as well as academic pieces focused primarily on psychology and mental health. Read more
Medically Reviewed By – Dr. Jessica Pyhtila, PharmD
Dr. Jessica Pyhtila is a Clinical Pharmacy Specialist based in Baltimore, Maryland with practice sites in inpatient palliative care and outpatient primary care at the Department of Veteran Affairs. Read more

Drug Enforcement Administration. “Fentanyl.” Accessed August 28, 2022.

American Academy of Family Physicians. “Opioid Conversion Table.” Accessed August 28, 2022. “Hydromorphone.” March 3, 2022. Accessed August 28, 2022. “Fentanyl.” March 3, 2022. Accessed August 28, 2022.

Baldini, Angee; Von Korff, Michael; & Lin, Elizabeth H.B. “A Review of Potential Adverse Effects of[…]actitioner’s Guide.” Primary Care Companion for CNS Disorders, 2012. Accessed August 28, 2022.

Centers for Disease Control and Prevention. “Death Rate Maps & Graphs.” June 2, 2022. Accessed August 28, 2022.

Centers for Disease Control and Prevention. “2019-2020 Prescription Opioid Overdose Data.” February 28, 2022. Accessed August 28, 2022.

PsychDB. “Opioid Use Disorder.” May 3, 2021. Accessed August 28, 2022.

Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.