The Brain’s Response to

Opiates

Hi, my name’s Sara Bellum. Welcome to 

my magazine series exploring the brain’s 

response to drugs. In this issue, we’ll 

investigate the fascinating facts about 

opiates. 

If you’ve ever seen “The Wizard of Oz,” then 

you’ve seen the poppy plant—the source of a 

type of drug called an opiate. When Dorothy 

lies down in a field of poppies, she falls into 

a deep sleep. No wonder the Latin name

of this plant—Papaver somniferum—means 

“the poppy that makes you sleepy.” 

Opiates are made from opium, which 

comes from the poppy plant. They can 

have important medical benefits—they’re 

powerful painkillers, they are sometimes 

prescribed to control severe diarrhea, and 

they can also be found in cough medicine. 

Maybe you’ve heard of drugs called Vicodin, 

morphine, or codeine. These are examples 

of opiates. When used properly for medical 

purposes, they can be very helpful. Opiates 

used without a doctor’s prescription or in 

ways other than how they are prescribed, 

can be dangerous and addictive.

Heroin is another example of an opiate, but 

it isn’t used as a medicine—it’s used to get 

high. 

The Brain’s Response to

Opiates

The Search Continues

There’s still a lot that scientists don’t know 

about the effects of opiates on the brain. 

Maybe someday you will make the next big 

discovery.

Until then, join me—Sara Bellum—in the 

other magazines in my series, as we explore 

how drugs affect the brain and 

nervous system.

Opiates can make you throw 

up—this can even happen to 

someone given opiates by a 

doctor—which is why many 

people don’t like taking them. 

Your brain produces its own versions 

of opiates, called endogenous 

opioids. These chemicals act just like 

opiates, binding to opiate receptors. 

Endogenous opioids help your body 

control pain. If you’ve ever felt pleasantly 

relaxed after exercising a lot, that feeling 

was probably caused by the release of this 

natural chemical in your brain.

Surprising Facts

National Institute on Drug Abuse

Opiates

 on the

 Brain

Mind Over Matter is produced by the National Institute on Drug Abuse, National Institutes of Health, U.S. Department of Health and 

Human Services. These materials are in the public domain and may be reproduced without permission. Citation of the source is appreciated. NIH 

Publication No. 09-3856. Printed 1997. Reprinted 1998, 2000, 2003, 2005, 2006, 2007. Revised 2009.

For more information, visit:

www.teens.drugabuse.gov

To learn more about opiates and other drugs of abuse, or to order 

materials on these topics, free of charge, in English or Spanish, 

visit the NIDA Web site at www.drugabuse.gov or contact 

the DrugPubs Research Dissemination Center at

877-NIDA-NIH (877-643-2644; TTY/TDD: 240-645-0228).
limbic system

brainstem

spinal cord

DEEP INSIDE THE BRAIN

Opiates resemble natural chemicals that have binding sites in the 

brain and the body called opiate receptors. Scientists have identified 

three types of opiate receptors: mu, delta, and kappa (named after 

letters in the Greek alphabet). Each of these receptors is involved in 

different functions. For example, mu receptors are responsible for 

the pleasurable effects of opiates, and their pain-relieving properties. 

Opiates act on many places in the brain and nervous system, 

including:

• the limbic system, which controls emotions. Acting here, opiates 

can produce feelings of pleasure, relaxation, and contentment. 

• the brainstem, which controls things your body does 

automatically, like breathing. Opiates can act on the brainstem to 

slow breathing, stop coughing, and lessen feelings of pain.

• the spinal cord, which transmits sensations from the body. 

Opiates also act here to decrease feelings of pain, even following 

serious injuries. 

Whether it is a medication like Vicodin or a street drug like heroin, 

the effects of opiates (and many other drugs) depend on how much 

you take and how you take it. If opiates are swallowed as pills, they 

take longer to reach the brain. If they are injected, they act faster 

and can produce a quick, intense feeling of pleasure followed by a 

sense of well-being and a calm drowsiness.

How Do Opiates Work?

Long-term opiate use changes the way nerve cells work in the brain. This happens even 

to people who take opiates for a long time to treat pain, as prescribed by their doctor. 

The nerve cells grow so used to having opiates around that when they are taken away 

suddenly, the person can experience a wide range of symptoms in the brain and body. 

These are known as withdrawal symptoms. 

Have you ever had the flu? You probably experienced symptoms such as aching, fever, 

sweating, shaking, or chills. These are similar to withdrawal symptoms, but withdrawal 

symptoms are much worse. Yuck! 

That is why, when used as medicine, opiates should be carefully monitored by a 

doctor—so that a person knows how much to take and when and how to stop taking 

them to lessen the chances of withdrawal symptoms. Eventually, the cells will work 

normally again, but that takes time.

Someone who is addicted to opiates has other symptoms as well—they cannot control 

how much drug they take, even though it may be having harmful effects on their life 

and their health. They have strong urges to take the drug—called cravings—and they 

don’t feel satisfied by natural rewards (chocolate, a walk on the beach). 

How Does Someone Become Addicted to Opiates?