How long does morphine last?

Morphine’s duration of action varies between 1.5 and 4.5 hours but can be longer when used in higher doses or for longer periods of time. More on morphine effects here.

minute read

Therapeutic effects of morphine generally last for about 4 hours, although duration of action is related to mode of administration as well as details about individual dosing.

Learn more about the addiction potential of morphine (opium), important treatment considerations, what you can do to address your drug use problem…and explore your long-term rehab and recovery options in our guide on opium addiction treatment process and programs. Help is available TODAY!

Then, we invite your questions about morphine, including signs of morphine addiction and getting treatment for morphine addiction, at the end.

Morphine effects on the body and brain

Morphine induces a wide range of pharmacologic effects on the body and brain such as analgesia, euphoria, somnolence, respiratory depression, diminished gastrointestinal motility and physical dependence. However, morphine also has the potential to change the way the brain functions. Why is this?

This is because morphine acts on the central nervous system in different ways, affecting the m-receptors, the k- and d-receptors respectively. Additionally, analgesia induced by morphine is activating at least three areas of the central nervous system: the periaqueductal-periventricular gray matter, the ventromedial medulla and the spinal cord.

Morphine, when administered according to a schedule, may affect from one to all three areas at once, which will manifest a greater number of effects. In terms of specific effect on the body, the m-receptors are responsible for the modulation of pain, analgesic effects, respiratory depression, miosis, feeling of euphoria, and decreased gastrointestinal activity. The group of m 2-receptors is involved in drowsiness, nausea, and mental clouding while the k-receptors are involved in analgesia, diuresis, sedation, dysphoria. The d-receptors are also affected by morphine and are involved in delusions and hallucinations.

Morphine duration of action

The terminal half-life for morphine varies between 1.5 and 4.5 hours. However, patients have reported much longer duration of action due to higher dose administration or protracted use. Keep in mind that (for all modes of administration) late respiratory depression can occur up to 24 hours after administration of morphine.

Epidurally injected as part of anesthesia, morphine acts really strong and fast, due to the circulation of morphine in spinal fluids, which get directly to the brain. In such cases peak plasma concentrations are reached within 15 minutes after administration of 3mg of morphine.

How long do morphine effects last?

Duration of action of the effects of morphine depend upon the mode of administration. When morphine is administered through epidural injection into the spinal fluid, it has a terminal half-life varying from 39 to 249 minutes. That is a bit shorter range compared to intravenous or intramuscular injection of 1.5 to 4.5 hours. And believe it, or not, only 4% of the morphine dose reaches to the brain. After intrathecal bolus injection of morphine, there is a rapid distribution phase of 15 to 30 minutes and a half-life in the of 42-136 min.

How long does a morphine high last?

Euphoric effects of morphine last for 4 to 6 hours. Onset of morphine effects takes place in 15 to 60 minutes. One interesting fact about morphine use is that as you grow older, the analgesia will last longer even with the same dose of morphine administered and you will experience the same high effects.

Morphine time in the body

A regular morphine user begins to eliminate morphine within 2 hours of administration of a single dose. Only 36% of morphine binds with proteins and 54% for muscle tissue. Excreted by the kidneys through urine in about 90%, only 10% are left to feces to eliminate morphine out of the body. However, up to 12% of morphine manages to leave the body without being metabolized and remains unchanged and can be recovered in the urine. In terms of drug testing, morphine can be detected in urine based drug tests up to a day or two after dosing.

Morphine high effects

As with any other drug, euphoric effects depend on the dose of morphine is administered, the route is taken, the history of drug abuse and dependence, the level of tolerance developed to morphine etc. Here is a list of the most common effects that can occur even as you feel effects of euphoria.

  • analgesia
  • constipation
  • cramping
  • depressed consciousness
  • depressed heart rate
  • diminished reflexes
  • drowsiness
  • euphoria
  • flushing of face and neck
  • lethargy
  • mental clouding
  • nausea and vomiting
  • pupils fixed and constricted
  • reduced gastrointestinal activity
  • relaxation
  • respiratory depression
  • sedation
  • sweating

Morphine duration questions

Do you still have questions about the duration of action of morphine, its excretion, or effects? We invite you to use the following section for your comments and questions. We try to respond with a personal and prompt answer ASAP.

Reference Sources: Hazardous Susbstances Data Bank TOXNET: Morphine
National Highway and traffic Safety Administration: Morphine (And Heroin)
Daily Med: Astramorph (morphine sulfate) Injection [AstraZeneca LP]
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.


Leave a Reply

Your email address will not be published. Required fields are marked *

I have read and agree to the conditions outlined in the Terms of Use and Privacy Policy.

  1. I’m on kapanol for chronic pain but had a total gastrectomy and they don’t seem to be giving as much pain relief since surgery why is that please

  2. I got an injection through an IV at the emergency room last night of morphine and I have very much bad cramping constipation depression still today
    Is this normal?
    How long do the side effects of morphine last?

  3. Hi, I have ABG 30 mg morphine sulfate. What is the actual half life? Need to know because I’m starting suboxone treatment soon. Thanks

  4. My father was suffering from cancer at 4th stage primary site was detected as lung and upper gastrointestinal tract. His chemotherapy had been started and now the doctors have given him the 5 capsules of morphine sulphate because of chronic pain. I want to ask you that is it safe giving him 5 capsules because the pain is really too severe, does morphine also loose resisting power with time?…. What should we do to stop this pain?.. Can we give them for months?

  5. I was given toradol for migraine on 11/28/17 and the next given morphine for the same migraine. How long do these side effects last? Ive been groggy since then, anxious, clouded, and cant seem to get over the feeling. How long until i feel normal? Also is it okay to get a pain killer one day and then a narcotic the other day?

  6. If 15mg of MSIR/Morphine Sulfate brand name Roxane was taken on a Tuesday morning, would it be totally undetected in the urine the following Friday morning, for sure? So 72 hours after taking the dose.

  7. Hi iv been using 45mg SR morphine & 5ml10 of orimorph ever 4 hours. Recently iv been having problems breathing outwards at night. It’s like my body needs to be reminded to breath out. I go long periods at night b4 taking a breath. Then struggle to breath out. Almost like my body doesn’t want to let go & have freaked several friends out. I can’t stop the pain relief as I have joint dislocations but should I speak to Dr.

  8. why is it that I am on a regime to take less and less morphine each 14 days …I am at 105 mg morning …60 mg supper …60 mg ….nighttime…..yet my motility has worsened 20 fold?? from when I was taking 300 mg a day? Why??? and the motility pin is 30 times worse than my back pain..

  9. @Jack I also have had cancer and had a world of depression anxiety and pain from it all. My oncologist started me on CBD oil which is legal in all States now.. This may benefit you also. Xoxo

  10. I had a shot of morphine at hospital on Sunday an my breathing is shortened…they gave me pain killers generic tylenol with codeine an i didn’t know it wasn’t good to mix…how long will my breathing be like this

  11. I have cancer (sacral chordoma) and am dependent on morphine for pain control. Obviously, you are dealing with abuse of the drug and addiction that has moved beyond therapeutic use, but still, I find your information valuable. I’ve been on morphine since 2011 when I had 10 lbs. of tissue/sacrum/coccyx removed that was invaded by the tumor, and some of the subsequent pain I’ve experienced has been due to nerve endings that were lost in the process. Lyrica has been helpful in diminishing the nerve pain and was how my PCP at the time weaned me from large daily doses of MS to a relatively lower maintenance level of 30mg TID MSER, along with hydromorphone 8mg TID and supplemental 4mg PRN x 1. My primary concern recently has been the possible effect of sensitivity, the reduced analgesic effect of morphine, combined with the recurrence of small tumors in the surgical bed. It’s impossible, of course, to tell what exactly is happening. Are these small tumors (which my oncologist has called “indolent”) the cause of additional pain, or am I beginning to experience opioid tolerance? Should I hope for additional opioids? or will that increase my tolerance (if that is what I am experiencing)? Does it really matter if my dependence accelerates, since I am out of treatment options (my surgeon said I was too high-risk for further surgeries and my rad-onc has said I’ve maxed out on life-time dose of radiation. It seems to me that I’ll take this situation to the grave, eventually, as chordoma slowly eats away at my anatomy. Thoughts? Suggestions? Questions?


    1. Hi Patrick. It might show up on the drug test. But, tell the toxicologist that you were given morphine at the hospital, and show the medical report.

  12. I have been taking 200 MG of morphine once and rarely twice a day for nearly 3 months. I’ve been wanting to quit and now that I’m going for a new job that does random drug test I need to quit. How long will it take for me not to test negative for the job and how long will it be going thru with drawls?

  13. Hi,

    My friend just received a shot of morphine after dislocating his shoulder. However, we are on vacation and we are wondering if it is safe for him to drink alcohol about 4 hours after taking the shot.

  14. Is 100 mg er of morphine ear very strong? I have chronic back conditions with constant pain. I went from 60 to 100 but really could not tell much difference.

  15. Hi, I recently had cancer surgery and was given a morphine epidural for pain management. I so disliked the hallucinogenic effects that I insisted the medication be stopped after 3 days. After that I was on no drugs whatsoever. However the euphoria lasted for over three weeks. Is this unusual? Thank you.

    1. Hi, Little Bear. I suggest you consult your doctor for any changes in taking your medicine, or call your pharmacist for advice.

  16. I’ve been on morphine and oxy cotton for 8 years the Dr now have taken me off of them. how long will it take for both of the drugs to get out of my system and for me to lead a normal life again

    1. Hello Jackie. Since you’ve been taking morphine and oxy cotton for a long time, so it could take mounts for the drugs to leave your system. However, with a good tapering plan prescribed by your doctor, you will be able to withdrawal safely.

  17. I was given morphine 3-4 times within a 4 hour period of being in a serious roll over accident. However, when I had a blood sample taken from me approximately 2-2.5 hours after administration intravenously, there was no trace of the morphine in my blood sample. What could the possibilities be for this conclusion? I know that for a fact the test was for any known chemical substance including alcohol. Please give me some insight on this matter.
    Thank you

  18. Hi Jennifer. You can get the best and most accurate advise from your doctor. So, please call him/her as soon as possible and remember that every person metabolizes and eliminates substances at a different rate.

I am ready to call
i Who Answers?