How Long Does Morphine Stay in Your System?

Dangerous Interactions Are Possible

Morphine is in a class of medications known as opiate (narcotic) analgesics. It works by changing the way the brain and nervous system respond to pain. It is prescribed to relieve moderate to severe pain, especially for around-the-clock relief of pain that cannot be controlled by other pain medications. Knowing how long morphine remains in the system can help prevent accidental overdose or dangerous interactions with other medications or alcohol.

Brand names for morphine include Avinza, Kadian, Morphabond, MS Contin, Oramorph SR, and Roxanol-T. Morphine can also be a drug of abuse, known by street names of Dover's Powder, Paregoric, and Laudanum.

How Morphine Affects Your System

Morphine is prescribed in several different forms, including a liquid solution and extended-release tablets and capsules. The timing of dosage is important for it to reach therapeutic levels but not cause it to reach a level that could cause an overdose.

After taking a dose, the effects begin within 15 to 60 minutes and last 4 to 6 hours. Extended-release formulas are designed to deliver the dosage in stages so the effects last longer, for 12 to 24 hours. Morphine has a short half-life, with half of it metabolized in 1.5 to 7 hours. Most of a single dose of morphine has been eliminated in the urine within 72 hours.

Morphine works on pain centers of the brain to provide pain suppression, but there are many other effects as well. They include euphoria, depressing breathing, constricted pupils, reducing gastrointestinal activity, drowsiness, dysphoria, and an altered mental status.

The body becomes tolerant when morphine is used over time and dosage may need to be adjusted to provide the desired effects. Morphine also leads to dependence and the body can have withdrawal symptoms if it is stopped. For this reason, it is important to follow the schedule provided by your doctor when it is decided to stop morphine.

What to Avoid With Morphine in Your System

Morphine depresses the respiratory system and slows the heart rate, so there are risks of interactions that can lead to coma.

Dangerous interactions might happen with barbiturates, benzodiazepines, antidepressants, MAO inhibitors, and antihistamines, among many other medications. You must not drink alcohol or use any medication that contains alcohol when you are using morphine.

Carefully go over the list of medications and supplements you have been using, plan to use, or plan to stop using so your doctor can adjust dosages to try to prevent dangerous interactions. Don't start, stop, or change dosages of any medications while on morphine without consulting your doctor.

A previous history of breathing problems, including asthma and COPD, are reasons to be even more cautious with the use of morphine. Don't breastfeed while you are taking morphine as it will pass through your milk to your child. If you are pregnant or plan to become pregnant, discuss this with your doctor as there is a risk of withdrawal in newborns of mothers who have prolonged use of morphine.

Preventing a Morphine Overdose

A morphine overdose can happen when it interacts with other medications, when doses are given too close together, or too much morphine is given. Don't crush or cut an extended-release tablet or capsule as that may deliver too much morphine at one time. Overdoses can also be seen when it is taken nonmedically by routes such as injection and in combination with other drugs. Some symptoms of morphine overdose include:

In case of a morphine overdose, call 9-1-1 or the poison control center at 1-800-222-1222. First-responders should be able to revive the victim with Narcan but only if they are notified soon enough.

How Long It Takes for Morphine to Leave Your System

Morphine is broken down by the body and excreted in the urine, with most of a single dose gone after 72 hours. However, with longer use or heavier doses, the time it takes to clear out of the body can be longer. If a person has become dependent on morphine, they may begin to experience withdrawal symptoms 6 to 12 hours after the last dose.

If you have been prescribed morphine, be aware that it can be detected on a urine drug screen such as given for employment. Disclose your prescription to the testing lab so they can interpret your test accurately.

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Article Sources

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  2. Berkowitz BA. The relationship of pharmacokinetics to pharmacological activity: morphine, methadone and naloxone. Clin Pharmacokinet. 1976;1(3):219-30.


  3. Clinical Guidelines for Withdrawal Management and Treatment of Drug Dependence in Closed Settings. World Health Organization; 2009.

  4. Morphine. Drugs and Lactation Database (LactMed) [Internet]. Published 2006.

Additional Reading

  • Morphine. MedlinePlus NIH.

  • Opiates. Mayo Medical Labs.

  • Morphine (and Heroin). National Highway and Transporation Safety Administration.