Addiction | 4 min read

How Opiates Affect the Brain & Body

Medically Reviewed

Medically Reviewed By

Dr. Po-Chang Hsu

Dr. Po-Chang Hsu

On September 5, 2022

Written By

Amanda Stevens

Amanda Stevens, B.S.

On January 24, 2019

How Opiates Affect Your Brain And Body
Reading Time: 4 minutes

Opiate abuse has become a national crisis and has even been declared a public health emergency. Accounts of opiate addiction are increasing at an alarming rate and are often associated with prescription drug abuse and misuse. With the instances of opiate addiction being so high, the public and the medical community are calling for alternatives to this once-respected treatment. Below is a sampling of the type of effects that this drug has on the brain and body.

Effects of Opiates on the Brain

opioids cause changes in the brain through binding to certain receptors. The drug instructs these receptors to release chemicals like dopamine. These chemical releases are similar to those occurring naturally through engaging in pleasurable activities. Not only does the brain come to rely on this artificial release, but it can also begin to associate certain situations with the anticipation of receiving the drug. This association is known as Pavlovian conditioning, where places, events, and scenarios can trigger a user’s desire for the drug.

Over time, the brain can depend on the drug’s effects. What was once able to be produced naturally has now received the message that it is no longer needed. In a sense, the brain gets lazy. An individual is subtly encouraged, by the brain, to continue supplying the needed chemicals through consumption of the substance.

With dependence comes tolerance, or the need to consume higher drug levels to produce similar pleasure. The receptors for the opiates become desensitized, and more of the drug is needed to experience prior sensations of gratification. Those using opioids for pain relief are likely to experience breakthrough pain and will commonly seek a higher dosage from their practitioner to manage it. Those using opioids illegally will find that they are not experiencing as much high and may engage in drug-seeking behavior.

The effects of opiate usage on a developing brain are very pronounced. Studies of children exposed to opiates in utero reveal that exposed children suffer from lower mental capabilities, regardless of how they are raised after birth. This impairment of cognitive ability does not improve and has been found to worsen over time for some. Children exposed to opiates before birth can suffer for life.

The physical structure of the adult brain is also found to be affected by opioid dependence. Those with a prolonged history of usage were discovered to have less gray matter in the brain’s frontal areas than the average non-user. Not only does gray matter hold the neurons for physical activity, but it has also been found to regulate social attitudes, such as the extension of empathy and exercise of conscience. This lends itself to the concept that prolonged opioid usage reduces the user’s ability to engage in compassion and pro-social behavior. As these studies of reduced gray matter were conducted on deceased individuals, it is unknown whether the matter can be recovered after abstaining from the drug.

Before the growing awareness of the dangers of prescribing opioids, the drug was even considered a solution for binge eating and obesity. The properties of the drug were found to block the receptors in the brain, which affect the release of pleasure chemicals related to eating, thereby causing enjoyable foods to lose their appeal. As a result, an opioid user can lose the ability to enjoy eating.

Effects of Opiates on the Body

Opiates reduce heartbeat and breathing rates, which contribute to the sensation of being relaxed. However, the downside of this depression of aerobic activity is that the brain often cannot receive enough blood and oxygen to function properly. In cases of overdose, the ability to breathe becomes impossible, and many have died due to a lack of oxygen to the brain.

Regarding the effect of opiates on appetite, the impact on the body can go either way. In one instance, a user may find that the lack of pleasure gained from eating – especially when combined with experiences of nausea and vomiting – results in severe weight loss. In other instances, the user will find themselves consuming even more food in an attempt to regain the pleasure of eating. This latter scenario can contribute to obesity for the user. Both undernourishment, and over-nourishment, are significant physical health risks.

There are also gastrointestinal effects. Opioid users can suffer from an acute form of constipation called opioid-induced constipation (OIC). This occurs because the substance relaxes the intestinal function, resulting in a build-up of matter. When the intestines are not clear, they cannot absorb fluid and nutrients, leading to dehydration and further malnutrition. The prescribing of oral laxatives is often called for in these situations, which can be problematic if the user also suffers the common side effects of nausea and stomach pain.

As if these effects were not enough, prolonged opioid use can negatively affect sex drive and performance. Erectile dysfunction has been noted in males who use opioids, and desire decreased for males and females using the drug. In addition, males who persist in opioid usage can suffer a sharp reduction in testosterone production.

The experience of physical withdrawal from opiates can be extremely unpleasant for the body. The withdrawal process can begin within 1-2 days from the last dosage and with a feeling of being on edge. As it progresses, the symptoms mimic severe flu, complete with nausea, diarrhea, and chills. Treatment centers can be utilized to reduce the severity of these symptoms while detoxing from the drug.

And There’s More

The negative effects of opiates don’t end with these detriments to the brain and body. There are many more consequences, some of which are only now being studied. In addition, those struggling with opioid abuse and addiction often experience psychological and relationship trauma, which extends the issue far beyond physical concerns.

If you or a loved one are struggling with addiction to opiates or another substance and seeking a New York or Connecticut treatment facility, reach out to Ascendant today. Our drug abuse treatment program can help you get back on your feet.

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Amanda Stevens


Amanda Stevens, B.S.

Amanda is a prolific medical content writer specializing in eating disorders and addiction treatment. She graduated Magna Cum Laude from Purdue University with a B.S. in Social Work. Read more

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  1. What is the U.S. Opioid Epidemic? Published October 27, 2021. Accessed September 5, 2022.
  2. Kosten TR, George TP. The Neurobiology of Opioid Dependence: Implications for Treatment. Sci Pract Perspect. 2002;1(1):13-20.
  3. Schulteis G, Koob GF. Reinforcement processes in opiate addiction: A homeostatic model. Neurochem Res. 1996;21(11):1437-1454. doi:10.1007/BF02532385
  4. Harrison LM, Kastin AJ, Zadina JE. Opiate tolerance and dependence: receptors, G-proteins, and antiopiates. Peptides. 1998;19(9):1603-1630. doi:10.1016/s0196-9781(98)00126-0
  5. Nygaard E, Moe V, Slinning K, Walhovd KB. Longitudinal cognitive development of children born to mothers with opioid and polysubstance use. Pediatr Res. 2015;78(3):330-335. doi:10.1038/pr.2015.95
  6. Cantin P. Researchers discover asphyxia trigger in opioid poisoning. Published January 26, 2011. Accessed September 5, 2022.
  7. Kshatriya GK, Acharya SK. Triple Burden of Obesity, Undernutrition, and Cardiovascular Disease Risk among Indian Tribes. PLOS ONE. 2016;11(1):e0147934. doi:10.1371/journal.pone.0147934
  8. Sizar O, Genova R, Gupta M. Opioid Induced Constipation. In: StatPearls. StatPearls Publishing; 2022. Accessed September 5, 2022.
  9. ISSM. How could opioid use affect sexual health? ISSM. Accessed September 5, 2022.
  10. MedlinePlus. Opiate and opioid withdrawal: MedlinePlus Medical Encyclopedia. Accessed September 5, 2022.