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Analgesics, Opioid

Definition, Purpose, Description, Recommended dosage, Precautions, Side effects, Interactions

Opioid analgesics, also known as narcotic analgesics, are pain relievers that act on the central nervous system. Like all narcotics, they may become habit-forming if used over long periods.


Opioid analgesics are used to relieve pain from a variety of conditions. Some are used before or during surgery (including dental surgery) both to relieve pain and to make anesthetics work more effectively. They may also be used for the same purposes during labor and delivery.


Opioid analgesics relieve pain by acting directly on the central nervous system. However, this can also lead to unwanted side effects, such as drowsiness, dizziness, breathing problems, and physical or mental dependence.

Among the drugs in this category are codeine, propoxyphene (Darvon), propoxyphene and acetaminophen (Darvocet N), meperidine (Demerol), hydromorphone (Dilaudid), morphine, oxycodone, oxycodone and acetaminophen (Percocet, Roxicet), and hydrocodone and acetaminophen (Lortab, Anexsia). These drugs come in many forms—tablets, syrups, suppositories, and injections, and are sold only by prescription. For some, a new prescription is required for each new supply—refills are prohibited according to federal regulations.

Recommended dosage

Recommended doses vary, depending on the type of opioid analgesic and the form in which it is being used. Doses may be different for different patients. Check with the physician who prescribed the drug or the pharmacist

Analgesics, Opioid

Opioid analgesics
Drug Route of administration Onset of action (min) Time to peak effect (min) Duration of action (h)
Strong agonists
Fentanyl (Sublimaze) IM 7–15 20–30 1–2
IV 1–2 3–5 0.5–1
Hydromorphone (Dilaudid) Oral 30 90–120 4
IM 15
IV 10–15 30–60 2–3
Sub-Q 30 15–30
Levorphanol (Levo-Dromoran) Oral 10–60 90–120 4–5
IV 60 4–5
Sub-Q 10–60 within 20
Meperidine (Demerol) Oral 15 60–90 2–4
IM 10–15
IV 30–50 2–4
Sub-Q 1
Methadone (Dolophine) Oral 30–60 90–120 4–6
IV 10–20 60–120 4–5
Morphine (many trade names) Oral 60–120 4–5
IM 10–30
IV 30–60 4–5
Epidural 10–30 20 4–5
Oxymorphone (Numorphan) IM 10–15 30–90 3–6
Sub-Q 5–10 15–30 3–4
Mild-to-moderate agonists
Codiene (many trade names) Oral 30–40 60–120 4
Im 10–30 30–60 4
Sub-Q 10–30 4
Hydrocodone (Hycodan) Oral 10–30 30–60 4–6
Oxycodone (Percodan) Oral 60 3–4
Propoxyphene (Darvon, Dolene) Oral 15–60 120 4–6
Butophanol (Stadol) IM 10–30 30–60 3–4
IV 2–3 30 2–4
Nalbuphine (Nubian) IM within 15 60 3–6
IV 2–3 30 3–4
Sub-Q within 15 3–6
Pentazocine (Talwin) Oral 15–30 60–90 3
IM 15–20 30–60 2–3
IV 2–3 15–30 2–3
Sub-Q 15–20 30–60 2–3

who filled the prescription for correct dosages, and make sure to understand how to take the drug.

Always take opioid analgesics exactly as directed. Never take larger or more frequent doses, and do not take the drug for longer than directed. Do not stop taking the drug suddenly without checking with the physician or dentist who prescribed it. Gradually tapering the dose may the chance of withdrawal symptoms.


Anyone who uses opioid analgesics—or any narcotic—over a long time may become physically or mentally dependent on the drug. Physical dependence may lead to withdrawal symptoms when the person stops taking the medicine. Building tolerance to these drugs is also possible when they are used for a long period. Over time, the body needs larger and larger doses to relieve pain.

Take these drugs exactly as directed. Never take more than the recommended dose, and do not take the drugs more often than directed. If the drugs do not seem to be working, consult your physician. Do not share these or any other prescription drugs with others because the drug may have a completely different effect on the person for whom it was not prescribed.

Children and older people are especially sensitive to opioid analgesics and may have serious breathing problems after taking them. Children may also become unusually restless or agitated when given these drugs.

Opioid analgesics increase the effects of alcohol. Anyone taking these drugs should not drink alcoholic beverages.

Some of these drugs may also contain aspirin, caffeine, or acetaminophen. Refer to the entries on each of these drugs for additional precautions.

Special conditions

People with certain medical conditions or who are taking certain other medicines can have problems if they take opioid analgesics. Before taking these drugs, be sure to let the physician know about any of these conditions.

ALLERGIES. Let the physician know about any allergies to foods, dyes, preservatives, or other substances and about any previous reactions to opioid analgesics.

PREGNANCY. Women who are pregnant or plan to become pregnant while taking opioid analgesics should let their physicians know. No evidence exists that these drugs cause birth defects in people, but some do cause birth defects and other problems when given to pregnant animals in experiments. Babies can become dependent on opioid analgesics if their mothers use too much during pregnancy. This can cause the baby to go through withdrawal symptoms after birth. If taken just before delivery, some opioid analgesics may cause serious breathing problems in the newborn.

BREAST FEEDING. Some opioid analgesics can pass into breast milk. Women who are breast feeding should check with their physicians about the safety of taking these drugs.

OTHER MEDICAL CONDITIONS. These conditions may influence the effects of opioid analgesics:

  • head injury. The effects of some opioid analgesics may be stronger and may interfere with recovery in people with head injuries.
  • history of convulsions. Some of these drugs may trigger convulsions.
  • asthma, emphysema, or any chronic lung disease
  • heart disease
  • kidney disease
  • liver disease
  • underactive thyroid. The chance of side effects may be greater.
  • addison's disease (a disease of the adrenal glands)
  • colitis
  • gallbladder disease or gallstones. Side effects can be dangerous in people with these conditions.
  • enlarged prostate or other urinary problems
  • current or past alcohol abuse
  • current or past drug abuse, especially narcotic abuse
  • current or past emotional problems. The chance of side effects may be greater.

USE OF CERTAIN MEDICINES. Taking opioid narcotics with certain other drugs may increase the chances of serious side effects.

Side effects

Some people experience drowsiness, dizziness, light-headedness, or a false sense of well-being after taking opioid analgesics. Anyone who takes these drugs should not drive, use machines, or do anything else that might be dangerous until they know how the drug affects them. Nausea and vomiting are common side effects, especially when first beginning to take the medicine. If these symptoms do not go away after the first few doses, check with the physician or dentist who prescribed the medicine.

Dry mouth is another common side effect. Dry mouth can be relieved by sucking on sugarless hard candy or ice chips or by chewing sugarless gum. Saliva substitutes, which come in liquid or tablet forms, also may help. Patients who must use opioid analgesics over long periods and who have dry mouth should see their dentists, as the problem can lead to tooth decay and other dental problems.

The following side effects are less common. They usually do not need medical attention and will go away after the first few doses. If they continue or interfere with normal activity, check with the physician who prescribed the medicine.

  • headache
  • loss of appetite
  • restlessness or nervousness
  • nightmares, unusual dreams, or problems sleeping
  • weakness or tiredness
  • mental sluggishness
  • stomach pain or cramps
  • blurred or double vision or other vision problems
  • problems urinating, such as pain, difficulty urinating, frequent urge to urinate, or decreased amount of urine
  • constipation.

Other side effects may be more serious and may require quick medical attention. These symptoms could be signs of an overdose. Get emergency medical care immediately.

  • cold, clammy skin
  • bluish discoloration of the skin
  • extremely small pupils
  • serious difficulty breathing or extremely slow breathing
  • extreme sleepiness or unresponsiveness
  • severe weakness
  • confusion
  • severe dizziness
  • severe drowsiness
  • slow heartbeat
  • low blood pressure
  • severe nervousness or restlessness

In addition, these less common side effects do not require emergency medical care, but should have medical attention as soon as possible:

  • hallucinations or a sense of unreality
  • depression or other mood changes
  • ringing or buzzing in the ears
  • pounding or unusually fast heartbeat
  • itching, hives, or rash
  • facial swelling
  • trembling or twitching
  • dark urine, pale stools, or yellow eyes or skin (after taking propoxyphene)
  • increased sweating, red or flushed face (more common after taking hydrocodone and meperidine)


Anyone taking these drugs should notify his or her physician before taking opioid analgesics:

  • Central nervous system (CNS) depressants, such as anti-histamines and other medicines for allergies, hay fever, or colds; tranquilizers; some other prescription pain relievers; seizure medicines; muscle relaxants; sleeping pills; some anesthetics (including dental anesthetics).
  • Monoamine oxidase (MAO) inhibitors, such as phenelzine (Nardil) and tranylcypromine (Parnate). The combination of the opioid analgesic meperidine (Demerol) and MAO inhibitors is especially dangerous.
  • Tricyclic antidepressants, such as amitriptyline (Elavil).
  • Anti-seizure medicines, such as carbamazepine (Tegretol). May lead to serious side effects, including coma, when combined with propoxyphene and acetaminophen (Darvocet-N) or propoxyphene (Darvon).
  • Muscle relaxants, such as cyclobenzaprine (Flexeril).
  • Sleeping pills, such as triazolam (Halcion).
  • Blood-thinning drugs, such as warfarin (Coumadin).
  • Naltrexone (Trexan, Revia). Cancels the effects of opioid analgesics.
  • Rifampin (Rifadin).
  • Zidovudine (AZT, Retrovir). Serious side effects when combined with morphine.

Nancy Ross-Flanigan


Analgesic—Medicine used to relieve pain.

Central nervous system—The brain, spinal cord and nerves throughout the body.

Colitis—Inflammation of the colon (large bowel)

Hallucination—A false or distorted perception of objects, sounds, or events that seems real. Hallucinations usually result from drugs or mental disorders.

Inflammation—Pain, redness, swelling, and heat that usually develop in response to injury or illness.

Narcotic—A drug derived from opium or compounds similar to opium. Such drugs are potent pain relievers and can affect mood and behavior. Long-term use of narcotics can lead to dependence and tolerance.

Tolerance—A decrease in sensitivity to a drug. When tolerance occurs, a person must take more and more of the drug to get the same effect.

Withdrawal symptoms—A group of physical or mental symptoms that may occur when a person suddenly stops using a drug to which he or she has become dependent.

Additional topics

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