An Overview of Opioids

How They Work, How Long They Last, and How to Use Them Safely

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Opiates are a type of narcotic drug derived from the opium poppy plant that acts directly on the central nervous system (CNS) as a depressant. Opioids are synthetic or partially synthetic versions of opiates that are usually used in pain management. Today, the term opioid is often used to describe both opiates and opioids, both of which are highly addictive. Some are considered medically acceptable, while others are considered illegal substances.

Learn more about the variety of opioids, how they function in the body, and how to utilize them as safely as possible.

Symptoms of Opioid Withdrawal
Verywell / Cindy Chung

How Opioids Work

All humans have opiate receptors in the brain, spinal cord, and throughout the body. Opioids bind to these receptors and mimic the brain's neurotransmitters that provide pain relief, effectively blocking the perception of pain. Both opiates and opioids work similarly in the body, as the molecular structures of these compounds are closely related.

Beyond pain relief, opioids may also lead to feelings of euphoria and well-being, which can contribute to a feeling of "high" and addiction. This is one reason opioids are often abused.

Major Types of Opioids and Opiates

There are several types of opioids and opiates that are used for medical use and/or recreational drug use.


A naturally-derived opiate, codeine is a controlled substance used to treat pain and relieve cough. Codeine has a half-life of only three to four hours, and so is often prescribed in conjunction with aspirin or acetaminophen for additional pain relief.

Codeine may be detected in a urine-based drug test for 24 to 48 hours after intake.

Hydrocodone (Vicodin)

Hydrocodone is a narcotic opioid used for moderate to severe pain management. The compound and metabolites of hydrocodone stay in blood circulation for anywhere from three and a half to nine hours.

Hydrocodone may be detected in a urine-based drug test for three to four days after intake.

Morphine (Kadian, Avinza)

Morphine is the main alkaloid component of the opium poppy, and a powerful analgesic, or pain reliever. It is most commonly used in a hospital setting especially following surgery, but it may also be found outside of a medical setting.

Morphine stays in blood circulation for an hour and a half to four hours, depending on the method of delivery. It may be detected in a urine-based drug test for two to three days after intake.

Oxycodone (OxyContin, Percocet)

An opioid usually combined with acetaminophen, oxycodone is usually prescribed to treat moderate, short-term pain. The half-life for oxycodone is three and a half to five and a half hours, which means it may take around 20 hours to leave your blood circulation.

It may be detected in a urine-based drug test for three to four days after intake.


Often used in cases of severe pain management, fentanyl is a synthetic opioid 50 to 100 times more potent than morphine and utilized in patients who have developed a tolerance to other opioids. Fentanyl attaches to the brain's opioid receptors and increases the release of dopamine. It may also slow breathing.

Fentanyl has a half-life of two to four hours, depending on the method of delivery. It may be detected in a urine-based drug test for one to three days after intake.

Cases of fentanyl overdose have skyrocketed in recent years and are a leading factor in the opioid epidemic in the United States.


A direct derivative of the opium poppy, heroin is an illegal street drug that is used recreationally; it is not approved for use in a medical setting. It has a particularly short half-life, lasting only around 30 minutes.

Heroin is usually not detectable in a urine test after two days.

Opioid Addiction

Though highly effective for pain relief, opioid tolerance can develop quickly, as higher and higher dosages of the compound are required to achieve the same results of pain relief and to combat withdrawal symptoms. As the dosage increases, risk of overdose and accidental death climbs up, as well.

Even when taken as directed, opioids can be addictive, but the risks of addiction increase when prescription opioids are not taken as prescribed or are combined with other drugs or alcohol.

Opioids should not be discontinued suddenly: a weaning program is usually recommended by a physician.

If opioids are stopped abruptly, symptoms of opioid withdrawal may occur, including:

  • Nausea and cramping
  • Vomiting
  • Anxiety
  • Irritability
  • Insomnia
  • Muscle aches and joint pain
  • Flu-like symptoms, such as fever, chills, and runny nose
  • Restlessness
  • Sweating
  • Increased heart rate and breathing rate
  • Increased blood pressure
  • Pupil dilation

Opioids for Pain Management and Drug Testing

While the above detection periods are good estimates, whether your drug screen turns up positive for opioids also depends on how much is in your system at the time of the test. Some opioids may show up on drug tests more readily than others, depending on the drug and the test.

Morphine and codeine are detected by most urine drug tests, but not all tests can distinguish morphine from illicit substances such as heroin or opium. Other types of opioids may not be detectable by commonly used drug tests. For these reasons, care must be taken when interpreting opioid drug test results.

If you work in a drug-free workplace and are subject to random drug screens, it might be best to inform your supervisor of your pain management protocol before the situation comes up. Arming yourself with a note from your doctor can’t hurt either.

A Word From Verywell

Opioids are powerful pain relievers with a high likelihood of addiction. Pain medication overuse is a growing problem in the United States, and sometimes the pain treatment can become more harmful than the pain itself. If you or someone you know believe you might be developing a tolerance to opioids or are struggling with opioid addiction, call the Substance Abuse and Mental Health Services Administration (SAMHSA) hotline at 1-800-662-HELP (4357) or go to the SAMHSA website to locate a treatment facility near you.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Centers for Disease Control and Prevention. Prescription opioids. 2017.

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