The key differences between hydromorphone and morphine include their potency, some specific side effects, and their potential for abuse.
Hydromorphone is more potent, has less severe side effects, and appears to be abused to a greater extent than morphine.
Morphine and Hydromorphone
Morphine and hydromorphone belong to the class of drugs known as opioids (sometimes also referred to as narcotics).
These drugs all have a similar mechanism of action. They are all either developed from opium or synthetically manufactured to resemble substances that are derived from opium.
Hydromorphone and morphine are most often used for similar purposes (pain control) and in similar contexts (most often, for postsurgical pain and sometimes for the treatment of chronic pain).
Both drugs are controlled substances in the same category (Schedule II).
Hydromorphone is most often sold under the brand names Dilaudid or Exlago. Morphine may be marketed under the brand names MS Contin, Duramorph, DepoDur, or MorphaBond.
Both drugs also come in generic versions.
Modes of Administration
One of the main differences in hydromorphone and morphine is how the drugs are administered.
Both drugs come in immediate-release oral tablets, extended-release oral tablets, oral solutions, and rectal suppositories. They can also both be used for intramuscular or intravenous injection. Injectable forms are most often utilized only by clinics and hospitals and not generally given to individuals to use at home.
Morphine can also be given in a subcutaneous injection form, extended-release oral capsule form, and as a concentrated oral solution. Hydromorphone is not available in these forms.
Both drugs are considered strong opioid agonists.
Hydromorphone is the more potent drug, as it is between two and eight times more potent than morphine.
The half-life of oral Dilaudid is about three to four hours. The half-life of oral morphine is between two and four hours.
The potency differences suggest that morphine would be more appropriate in the treatment of chronic pain, whereas hydromorphone might be better suited for severe post-surgical pain or for people who have developed tolerance to opioids. These differences also suggest that abusers of the drugs are more likely to overdose on hydromorphone than morphine.
Side Effect Profiles
Both drugs are about equally as likely to produce the following side effects:
- Stomach pain or cramps
- Dry mouth
- Appetite loss
- Swelling in the face or throat
- Rash or hives
- Chest pain
- Trouble breathing or swallowing
Side Effects More Likely to Occur With Hydromorphone
The following side effects are more likely to occur with hydromorphone than morphine:
- Joint, back, or muscle aches and pains
- Posterior hypotension (dizziness when changing positions)
- Flushing of the skin
- Anxiety or depression
Side Effects More Likely to Occur With Morphine
Morphine may be more likely to produce the following side effects:
- Weight loss
- Muscle weakness
- Pinpoint pupils
- A bluish or purple tint to the skin
- Pain or difficulty urinating
- Alterations in heart rate
- Agitation or confusion
- Mood swings
There is a long list of drugs that can produce untoward interactions when used with either hydromorphone or morphine.
Morphine is more likely to decrease the effectiveness of diuretics, be associated with an increased risk for bleeding when used with blood thinners, and produce labored breathing when taken with certain drugs, such as erythromycin.
General Issues with Medical Use
Morphine is most often the first choice when individuals are treated for post-surgical pain. However, elderly individuals may be more likely to be given hydromorphone, as it is less likely to produce issues with confusion in this group.
Both morphine and hydromorphone are significant drugs of abuse. People with a prescription for either drug should be closely monitored by prescribing doctors.
Based on information provided by the Substance Abuse and Mental Health Services Administration (SAMHSA), misuse of either drug may occur at different rates among different age groups. The following was found in the U.S. for 2017:
- Overall age groups–About 6.2 million individuals reported using a product containing morphine at least once in their lives. Roughly 501,000 of these individuals reported misusing a morphine product at least once during the year (about 8 percent).
- Overall age groups–About 1.9 million individuals in the U.S. reported using a hydromorphone product at least once in their lives, and 244,000 reported misusing a hydrocodone product at least once in the prior year (about 12.6 percent).
- About 374,000 individuals between the ages of 12 and 17 reported using a morphine product at least once in their lives; 46,000 individuals reported misusing a morphine product at least once in the prior year (about 12 percent).
- About 32,000 individuals between the ages of 12 and 17 reported using a hydromorphone product at least once in their lives, and 9,000 reported misusing hydromorphone at least once in the prior year (about 28 percent).
- About 817,000 individuals between the ages of 18 and 25 reported using a morphine product at least once; 132,000 reported misusing a morphine product at least once in the prior year (about 16 percent).
- About 240,000 individuals between the ages of 18 and 25 reported using a hydromorphone product at least once; about 61,000 reported misusing hydromorphone once in the prior year (about 25 percent).
- About 5 million individuals over the age of 26 reported using morphine at least once; 323,000 individuals reported misusing morphine at least once in the prior year (about 6.5 percent).
- About 1.7 million individuals over the age of 26 reported using hydromorphone at least once; 174,000 individuals reported misusing hydromorphone at least once in the prior year (about 10 percent).
The data provided by SAMHSA indicates that the probability of experiencing a fatal overdose is higher for hydromorphone abusers; however, an overdose on either drug can be fatal.
Clinical data suggests that accidental overdoses of people in treatment may be more common with hydromorphone due to its higher potency.
Mistakes in dosing in clinical settings appear to be more likely with hydromorphone. This can increase the chances of an overdose in a treatment setting.
Morphine and hydromorphone are similar opioid drugs.
Based on the data, the most striking differences between the drugs are the increased potency of hydromorphone, some side effects that are more likely to occur with one drug compared to the other, and the fact that hydromorphone is more likely to be abused than morphine.