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How Opiates Work As Painkillers

Table of Contents

Opiates have been used for centuries as medication and recreational drug. The opioid crisis has many people taking a hard look at these psychoactive substances. Why do we use them and how do they work? Opioids can be a useful medication and a dangerous illicit drug. Understanding their power and how they affect the human brain can help you learn to respect this drug’s potency as a help or a hindrance to the people who take it. Learn more about opioids, pain relief, and how the drug can lead to addiction. 

What Is an Opiate?

An opiate is a psychoactive chemical that’s naturally found in a wide variety of plants and animals. In nature, they can serve multiple functions as a painkiller, a defense mechanism, and to subdue prey. Opiates can be partially or fully synthesized into new chemicals, in which case they are no longer true opiates, but fit into the overarching category of opioids. Synthetic opioids like fentanyl can be much stronger than naturally occurring opiates, which can be useful in a medical context and dangerous in recreational use.

Morphine is the most common opiate that’s used in medicine as a prescription painkiller. It’s been used for more than two centuries to treat injuries, post-surgery pain, and chronic pain symptoms. The chemical is derived from a naturally occurring alkaloid that’s found in the opium poppy plant. It can also be altered to create new chemicals like codeine and heroin.

Opiates have a powerful effect on the human brain. They may be effective in the treatment of pain symptoms, but they can also be powerfully addictive, leading to chemical dependence, opioid use disorders, and withdrawal symptoms. Your body can come to rely on the drug after prolonged use, depending on the amount you used and how long you use it. 

Your brain’s reward center is designed to notice activities that make you feel good by responding to certain chemicals. Then, the brain encourages you to repeat those actions by causing cravings or compulsions. This helps you to survive because you naturally seek food when you’re hungry and warm shelter when you’re tired. One of the chemicals your reward center responds to is opioids. Using powerful opioids for too long or in very high doses can cause your brain to mistake taking the drug for those important life-sustaining activities. 

The response to these powerful opioids can be so powerful; it causes you to push all of your other needs aside to find and take more opioids. 

How Does Pain Work?

To understand how opiates work, it’s important to first understand the role of pain and how it affects the body. Pain is an important part of your body’s normal functioning. It lets you know when something’s wrong and communicates to your reward and learning centers that whatever you did to get hurt should be avoided. Pain helps us survive, tells us when we need medical help, and allows us to avoid unnecessary damage to our bodies. However, it can also cause some problems. Pain can make it difficult to relax and heal from an injury, and chronic pain can lower your quality of life.

Pain starts at the sight of damage. Specialized nerve cells called nociceptors that are found in your skin, muscle, joints, cornea, organs and other tissue are designed to send pain messages to the brain. They pass messages from the site of pain, all the way to a part of the spine called the dorsal root ganglia, where the cell bodies of these neurons are located. From there, the message travels up to the brain where the information is processed and ends with you recoiling from the cause of pain and saying, “Ouch!”

Pain travels from neuron to neuron by releasing chemical messages that travel across space between the nerve cells called the synapse. The sending neuron releases pain signals into the synapse that bind to receptors on the receiving neuron. Then the nerve cell passes it on to the next one until the message reaches the brain.

Some chronic diseases and disorders can cause pain messages to fire continually. Cancer is an especially common disease that causes long-term pain symptoms. As cancer grows, it damages more of the body, causing more pain. Opioids are used to treat pain and allow people to relax and rest instead of feeling unnecessary pain. 

But how do opiates work in the body?

Opiates in the Brain

Opiates work in the brain like any psychoactive drug: by affecting the nervous system’s method of communication. However, opioids are a bit different from other drugs like stimulants and depressants. Stimulants cause a release of dopamine and stop excess dopamine from being removed from the brain and recycled. Depressants typically increase the effectiveness of GABA, a naturally occurring chemical. Both alter or affect other chemicals that already exist in the brain.

Opiates bind and activate its own opioid receptors directly. Why does a chemical that’s found in a plant that’s native to the Eastern Mediterranean get a parking spot in human brains? Because opiates are also naturally found in your brain. Chemicals called endorphins are released naturally and bind to opioid receptors to regulate pain in the body and promote recovery. You may have felt their effects after vigorous exercise. Technically, a “runner’s high” is a natural endorphin high. 

Opiates like morphine are incredibly similar to endorphins, and they can bind to and activate opioid receptors to a much greater degree. Where endorphins can promote relaxation and healing, morphine stop pain dead in its tracks—literally. Prescription opioids work by blocking pain signals in both the sending and receiving neurons. Weaker opioids like codeine are useful for mild pain symptoms and coughing while stronger ones like fentanyl can be used to manage severe pain like labor pains.

How Opioids Cause Addiction in the Brain

However, endorphins are one of the main “feel good” chemicals in which the reward center responds. Opioids can affect the brain in the same way as their naturally occurring counterparts. But since they are more powerful, they can be more enticing to your reward center. Abuse is especially dangerous. The reward center is a big fan of euphoric feelings and will mistake drugs that cause it for vitally important survival activities. Your brain will learn to encourage you to repeatedly use opioids, even through powerful cravings and compulsions that get out of control. 

Imagine if you were thirsty in a room with a water cooler and someone told you not to drink anything. Even if you wanted to comply, it would be difficult to resist a cool glass of water after a while. When you develop a severe opioid use disorder, your brain will treat opioids the same way. Even if you recognize the consequences it’s bringing to your life; you will have trouble resisting your brain’s compulsions. Addiction treatment can help you learn to cope with those cravings and the triggers that cause them.

Seeking Help for Opioid Use Disorder

If you or someone you love has used opioids and may be developing opioid use disorder, there is help available. Speak to an addiction treatment specialist at Ocean Breeze Recovery to learn more about your treatment options. Opioid addiction is a serious, chronic disease but it can be treated with the right help on your side. Call 855-960-5341 to begin the road to recovery today.


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Psychology Today. (2012). Meet Your Happy Chemicals – Psychology Today. Retrieved from

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