Long Term Effects of Morphine on the Brain (INFOGRAPHIC)

How does morphine work in the brain? A VISUAL aid for understanding morphine effects in the brain here.

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Reviewed by: Dr. Manish Mishra, MBBS

SUMMARY: Morphine causes changes in the form and function of specific brain areas. It affects incentive motivation, reward, and learning. After a period of abstinence, some deficits can last for months or years after last use.


Main Brain Effects

Prescription painkillers like morphine are used to treat moderate to severe pain and are often prescribed following surgery or injury, or for health conditions such as cancer. How does this strong painkiller work in the brain?

Long Term Effects of Morphine on the Brain (INFOGRAPHIC)

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Morphine directly targets the central nervous system and changes the way in which the body feels and responds to pain. More precisely, it binds to opiate receptors in the brain to change the neurochemical activity in the brain stem which can result in alteration of the automatic body functions.

In recent years, there has been a dramatic increase in the acceptance and use of prescription opioids for the treatment of chronic, non-cancer pain, such as back pain or osteoarthritis, despite serious risks and the lack of evidence about their long-term effectiveness.

However, this strong painkiller also affects regions in the brain responsible for pleasure and with regular use the brain starts to register the effects of the morphine as a reward. According to the 2016 National Survey on Drug Use and Health (NSDUH):

  • 6.8 million Americans used morphine in the past year.
  • 536,000 people reported misuse of morphine in the past year.

So, if you’re worrying about long term use, you’re not the only one! How does morphine affect the brain, exactly? Keep reading to learn more.

Morphine can cause regional neuroplastic changes in the  brain after only one month of daily administration.

How long is “long term”?

For short-term relief of severe acute pain morphine is used for about 4 weeks or 1 month. Long-term use is defined as using morphine for one month or longer, and is typically recommended for the management of severe chronic pain. However, morphine should never be taken longer than 12 years.

Chronic use of morphine = repetitive and pattern-followed morphine abuse that reflects negative consequences on:

  • person’s economic stability
  • social relationships
  • state of health

Nervous System Effects

As opioid use in America rises, it becomes increasingly important that we better understand the neurological and behavioral effects of these drugs. There are some known risks of using morphine. In fact, doctors have come to expect drug dependence, cognitive impairment, and a phenomenon known as hyperalgesia, an increase sensation of pain triggered by the pain medication itself. Still, some nervous system effects are still be researched and discovered.

This 2011 article published in the medical journal, Pain, noted the specially noxious effects of morphine on the brain. Morphine was found to decrease the amount of gray matter in the amygdala, an area responsible for neural reward-processing. This 2015 article published in the medical journal, Neurologia, found that, “the actions of morphine on both developing and adult brains produce alterations in the plasticity of excitatory postsynaptic sites of the brain areas involved in limbic system functions of reward and learning.” What do these findings mean in layman’s terms?

These recent findings are important, because they point to physical changes that can reinforce drug addiction. In simple terms, the brain adapts to morphine by dulling our natural responses to food, sex, or pleasure…encouraging use to take morphine for rewards that we normally find naturally. Because morphine can not only change brain function but also changes the structures and form of the brain, we need to be thinking about how to better manage pain in the long term. More on this in the section about tapering below.

The main effects of morphine on the brain include:

  • decrease in the volume of gray matter in the amygdala
  • depressed consciousness
  • diminished reflexes
  • general psychomotor impairment
  • possibility for seizures
  • slowed reaction time


Morphine is an incredibly potent analgesic pain reliever. Because it is known to cause strong addiction – and very uncomfortable withdrawal symptoms – doctors only prescribe morphine in cases of absolute need. In fact, the opiate has been found to affect over 10+ circuits in the brain. See the August, 2016 medical journal, Molecular Cells for a full list of brain reward circuits affected by morphine. Various changes are reflected in the distinct connectivity and function of brain reward circuits. Full article on Brain Reward Circuits in Morphine Addiction here.

Here are some of the ways that morphine affects neurotransmission.

  • Morphine affects m-receptors, and also interacts at k- and d-receptors.
  • It binds to opiate receptors within the limbic reward pathway.
  • It binds to receptors concentrated in areas of the pain pathway.
  • It causes sedation, relaxation and drowsiness
  • Morphine gives short-term feelings of emotional well-being, warmth and pleasure.
  • Morphine produces euphoria and elevated mood.

Here’s a graphic view of the neurological pathways that morphine affects:

Personality and behavior

In addition to the serious risks of addiction, abuse, and overdose, the use of morphine can have a number of side effects to your mental health. It can trigger depression, mental clouding, or abnormal thoughts. Further, sleeping problems are common when taking morphine. Morphine use has also be connected with a feeling of disconnectedness. Long-term or high dose users have reported delirium.

All of these side effects can cause other changes to personality and behavior. Changes include:

  • alterations in personality
  • apathy
  • destructiveness
  • compulsion to use morphine
  • inattentiveness
  • lethargy
  • neglecting formerly enjoyable activities and hobbies
  • obsessive behavior over obtaining morphine
  • sudden mood and action changes

What are typical morphine doses?

Only a doctor will be able to dose you appropriately with morphine. The risk for overdose and death is just too high to recommend dosing online. According to this FDA prescribing information for morphine sulfate oral solution, doctors are cautioned to be careful during dose selection, starting at the low end of the dosing range while carefully monitoring for side effects. Dosing errors with morphine are possible, due to confusion between different concentrations and between mg and mL. So, take care to ensure that you understand the proper dose is when beginning any morphine use.

Abuse typical doses

  • Per day recreationally …… 30-60 mg orally as a starting dose
  • Addicts can administer 1 to 3 times per day.
  • Addicts with high tolerance to morphine can use 2000-3000 mg daily.

Lethal typical doses

  • Overdose ………… 200mg is the least amount needed for overdose. But, in case of over sensitivity to morphine, 60mg can be fatal.

Occasional Tapering

When you’re taking morphine for long than a few weeks, a few things begin happening in the body. First, you develop drug dependence. This means that your brain and body adjust to the chemicals found in morphine in order to keep operating. In fact, they actually “speed up” some processes in order to counter the depressant effects of the painkiller. When you quit or lower dosage, you can expect specific symptoms of morphine withdrawal.

Second, you can expect to become more tolerant to morphine. Tolerance manifests as less effective pain relief, requiring more morphine more often in order to achieve therapeutic effect. Finally, morphine can produce hyperalgesia, a paradoxical increase in pain perception.

To counter these predicted effects, doctors suggest tapering anytime:

  • Take dosages greater or equal to 50 morphine milligram equivalents a day
  • You do not experience clinically meaningful improvement in pain and function.
  • You experience overdose.
  • You experience another serious adverse event.
  • You shows signs of substance use disorder.
  • You exhibit early warning signs for overdose risk such as confusion, sedation, or slurred speech.

You can find specific guidelines for tapering off morphine here:

CDC Guideline for Prescribing Opioids for Chronic Pain

Washington State Opioid Taper Plan Calculator

CDC Pocket Guide for Tapering Opioids

About the author
Lee Weber is a published author, medical writer, and woman in long-term recovery from addiction. Her latest book, The Definitive Guide to Addiction Interventions is set to reach university bookstores in early 2019.
Medical Reviewers
Dr. Manish Mishra, MBBS serves as the Chief Medical Officer of the Texas Healt...

All of the information on this page has been reviewed and verified by a licensed medical professional.


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  1. I have a cousin who has been abusing narcotics for over 35 years. It started with feigning pain and he has had at least 8 surgeries that were not needed. He has been on morphine and methadone now for a very long time. He has destroyed all extended family relationships, is unreliable for anything, lies, deliberately fixates on certain people and sets out to destroy them with lies. His partner is also an addict. He and his partner are both on disability. Has delusions and hallucinations. Takes about 1000 mgs per day and approx. 800 to 1000 mgs. of methadone per day. His immune system is failing, has pneumonia all the time, itching, pins and needles feeling, swollen legs, etc..blames all these side effects on illnesses. I am most positive his brain is damaged and he is unaware of this. The things he say’s and does he never owns, he denies but I suspect great memory loss.

    1. Hi Nastasia.There are people who may help your cousin. Call the helpline displayed on the website to get in touch with a trusted treatment consultant to discuss treatment options. Also, you can try staging an intervention. Consult with a certified interventionist, here are some useful links:

  2. My son was on morphine for months on end due to surgery and cancer. He hallucinates mostly about God but I am wondering if this is a mental condition or the effects of morphine. Please help.

  3. I am 70 years old with severe degenerative disc disease and facet arthrosis. Had to quit working due to pain 15 years ago. Tried every alternative to opiates, i.e. injections, PT, anti-inflammatories, muscle relaxers, etc. Allergic to all opiates except morphine. Was on 30 mg morphine sulfate ER BID for about 2 years then weaned off and pain returned. Have been on 15 mg morphine sulfate ER QD for a year. Never had cravings or any noticeable side effects even with withdrawal. However, worried about long term effects on life expectancy, etc. so weaning again. Pain is back and unable to do much of anything. Two questions: This time withdrawal has been bad mainly general body aching, malaise and chills still continuing after two weeks. Doctor says normal. Clonidine not helping. Is it normal for these symptoms to continue this long? Second question: Is there real evidence that using morphine responsibly shortens life or causes irreversible disease? Have read all the info on effects of morphine on the body and have never had any sign of any of them. The doctor will put me back on morphine if I want but I am leery and might live longer than the 12 year limit on morphine use.

  4. 11 years ago I was in a terrible car accident which left me with severed & damaged nerves in the wrist and hand. 13 surgeries later & I was referred to a pain specialist. Fast forward 11 years-daily Im prescribed 90mg Ms Contin ER, 120mg Oxycontin, 6 pills daily Percocet 10-325 & 600 Lyrica for pain. Honestly, I rarely leave comments. I figure my story isnt much different. But this is for the person who like me, couldn’t understand the total change in my personality and couldn’t figure why I felt so dead inside! Or for the family who can’t understand who their loved one has become and trying to find some way not to take it all personally. My Dr NEVER told me that these where typical long term use effects. Even when I mentioned them. Before pills, I was physically active. I was responsible, hard-working, creative, organized and motivated. Lots of friends, hobbies, 10yrs of good marriage etc. Not perfect but living my own life. NOW? I sit in my Shrinks office, anti depression scripts in hand, crying, begging, please FIX ME! Why can I not seem to get motivated and interested in living anymore? I was told I was bipolar & (my minor went major) suffering PTSD from accident/trauma & maybe this dosage/type I will feel better in few wks. I had now isolated myself to where I lost most of my friends, people we’re constantly commenting on my anger and irritability. My husband and I haven’t slept in the same bed together for almost 8 years & we will be getting a divorce soon. My house shades rarely open. I can’t throw papers, mags, etc away. I stopped taking care of myself… gained 40lbs & hate looking in mirror so I avoid leaving the house. …….. I’m just starting my journey to get to the other side. To find my way back from addiction and learn new ways to live with my chronic pain instead of just existing with pills. These drugs affect your brain. Scientific proven fact. I’m reaching down into the rabbit hole to help pull you up. Here, where ”true you” will be waiting… you can see that taking opiads destroys one of the most precious things you will ever own ….your health and your spirit. God bless you and good luck.

  5. Having read this, I can confirm that Morphine affects previously enjoyable activities, which for me was exercising.
    Over a decade ago my leg was smashed to pieces in a traffic accident, to put my leg back together they dosed me up with Morphine, and I think they gave me too much because I was out of it pretty hard, my mind went to a places it has never been before and thankfully never again, but then my leg got pin and it took me about a year to fully heal.
    However, went I tried to enjoy exercising, something had changed, it was no longer an enjoyable activity, all exercise became was tiring and exhausting with no emotional compensation, something that had to be done then became something that could be skipped because I wanted to conserve energy for things that mattered more.
    I honestly do not know if Morphine was the cause, but I can not think of anything else that may have affected my mind in such a manner, it has been over ten years and nothing has changed, physical effort is still no longer enjoyable and something that I will avoid if at all possible, any motivation to get fit or develop muscles is non existent, thankfully being a slim guy means I can hide my problem in plain sight.
    Thank you for the article.

  6. Morphine can cause a change in the personality of a person because it can cause a person to become agitated as a possible side effect, and causes memory loss due to morphine blocking the brain’s ability to strengthen at inhibitory synapses which is a key process the brain needs to store information.

  7. My husband is an amputee and has all kind of back problems. He sees a pain management Doctor once a month to get his morphrine. He takes morphrine IR 15mg twice a day and morphrine ER 100mg twice a day. He is usually a easy going man but about once or twice a week he gets ANGRY or mad over the smallest thing and then we have a huge blow up. He has been taking this for about 6 years and since his amputation about 20 years ago has been on just about every pain med.

    My question, is taking morphrine can it make you angry? He is also VERY forgetful but my main question can taking morphrine change your personality and make him mean? Thank you, Joan

    1. Hi Joan. Morphine may have an impact person’s behavior. I suggest that you speak with your husband’s doctor about his behavior, and you may consider family counseling. Keep in mind that your husband has gone through very serious life situation, so maybe he needs counseling sessions on his own.

  8. Just in case you don’t realize why you’re not getting comments on your blog, I was just accused of being spammy after writing about my experience with a user. Thanks you need to adjust your filters. Just because I know how to spell( and use spell check) doesn’t make me spam! Notice you only have 1 comment.

    1. Hi Lisa. Sorry for your troubles. Right now we’re working on new software, and some of the comments are marked as spam. However, you may send us the article’s link and your comment at info@addictionblog.org , and we’re going to post it manually.

  9. I have been on these drugs for many,many yrs.I am now whining off all of them.Although I have done this before,on my own,I would never suggest,that anybody do that.I am now working with a professional team,to help me do that safely.It consists of my family doctor,a senior nurse,(which is trained in that field)plus a pharmacist.They are great,understanding,patient,wonderful,and I am grateful every day for there help.I would love to speak,about what it has caused in my life.Everything was in shambles.My health,family,friends,my mind(in many ways)& the list goes on.I had been asking my doctors,to get off these horrid meds,to hear,hoe r u going to control my chronic pain.In one month,I have regained my memory,balance,depression state is much better,constipation,confusion,psychotic behaviour,not caring about important things,not able to carry a conversation, lost my self esteem,balance,sleeping deprevation,although I was insomiac for yrs,things got much worse.Lucky to get8 to 10 hrs,in as many days as 5,& that happens very often.I am totally exausted most of the time,with reason.my sleep specialist could not understand why I was still alive,after all these yrs,without any decent sleep.I ask myself that same question????? Well the important point,is that I have turned it around&doing very well.Everybody is impressed wih my progress.I am not naive enough to think this is over,but relieved that it is the beginning of a whole new life,.one of quality,and one I am so much looking forward to.So far,the withdrawals have been really acceptable.I am on the road to wellness.I could say much more,but I would have to write a long book.If ever I can help someone,I would jump at opportunatly Good luck to everyone going through this bad scene.Hope this will be of help..

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