Kratom - MS Contin (Morphine Sulfate) Interaction
Herbal: Kratom
Also Known As: Mitragyna speciosa, Biak-Biak, Cratom, Gratom, Ithang, Kakuam, Katawn, Kedemba, Ketum, Krathom, Kraton, Kratum, Madat, Maeng Da Leaf, Mambog, Mitragynine, Mitragynine Extract, Thang, Thom
Drug: Morphine Sulfate
Brand names:
MS Contin, Kadian, Avinza, Morphabond, Arymo ER

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Apr 20, 2025
Interaction Details
Morphine Sulfate is classified as belonging to the following category: Cns Depressants
Theoretically, concomitant use might increase the risk for adverse CNS depressant effects.
Kratom contains mitragynine, a mu-receptor agonist that may cause respiratory depression. Although results from animal research suggest that mitragynine causes less respiratory depression than the CNS depressant codeine, fatalities have been reported for patients who ingested a combination of kratom and O-desmethyltramadol, another mu-receptor agonist. Additionally, observational research suggests that adverse effects such as drowsiness and coma are more likely to occur in individuals taking kratom in combination with agents such as opioids and sedatives. Theoretically, ingesting kratom along with other CNS depressants can increase the risk of adverse effects, including drowsiness, coma, and/or severe or fatal respiratory depression.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Backstrom BG, Classon G, Lowenhielm P, Thelander G. [Krypton--new, deadly Internet drug. Since October 2009 have nine young persons died in Sweden]. Lakartidningen 2010;107(50):3196-3197.
- Kronstrand R, Roman M, Thelander G, Eriksson A. Unintentional fatal intoxications with mitragynine and O-desmethyltramadol from the herbal blend Krypton. J Anal Toxicol 2011;35(4):242-247.
- Jansen KL, Prast CJ. Ethnopharmacology of kratom and the Mitragyna alkaloids. J Ethnopharmacol 1988;23(1):115-119.
- Davidson C, Cao D, King T, et al. A comparative analysis of kratom exposure cases in Thailand and the United States from 2010-2017. Am J Drug Alcohol Abuse. 2020:1-10.
Interaction Details
Morphine Sulfate is classified as belonging to the following category: Cytochrome P450 2D6 (Cyp2D6) Substrates
Theoretically, kratom might increase the levels and clinical effects of drugs metabolized by CYP2D6.
In vitro research suggests that kratom extract inhibits CYP2D6 enzyme activity. However, human research shows that a single low dose of kratom tea 2 grams does not inhibit CYP2D6 activity. However, this kratom dose is lower than what is normally taken for psychoactive effects. In one case report, a 63-year-old male presented with possible serotonin syndrome after taking an unknown dose of kratom for up to 3 months along with serotonergic prescription medications bupropion, buspirone, desvenlafaxine, trazodone, and ziprasidone. It was hypothesized that kratom inhibited CYP2D6-mediated metabolism of buspirone and consequently increased systemic exposure to serotonin. In another case, a 37-year-old male stable for 15 years on amitriptyline presented with anticholinergic symptoms including xerostomia, dry eyes, and constipation, along with mildly elevated bilirubin and liver enzymes after taking progressively higher doses of up to 14 grams of kratom daily for 12 weeks. It was hypothesized that the adverse effects of amitriptyline were precipitated by CYP2D6 inhibition by kratom.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Kong WM, Chik Z, Ramachandra M, et al. Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay. Molecules. 2011;16(9):7344-7356.
- Eudaley ST, Brooks SP, Hamilton LA. Case Report: Possible Serotonin Syndrome in a Patient Taking Kratom and Multiple Serotonergic Agents. J Pharm Pract 2022.
- Tanna RS, Nguyen JT, Hadi DL, et al. Clinical Assessment of the Drug Interaction Potential of the Psychotropic Natural Product Kratom. Clin Pharmacol Ther 2023;113(6):1315-1325.
- Vanani NB, Stevanovic SG, Stevanovic N. Adverse Drug Interaction Between Kratom and Amitriptyline With Gastrointestinal and Mild Hepatic Effects. Cureus 2023;15(1):e33809.
Kratom Overview

Morphine Sulfate Overview
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Morphine is used to relieve moderate to severe pain. Morphine extended-release tablets and capsules are only used to relieve severe (around-the-clock) pain that cannot be controlled by the use of other pain medications. Morphine extended-release tablets and capsules should not be used to treat pain that can be controlled by medication that is taken as needed. Morphine is in a class of medications called opiate (narcotic) analgesics. It works by changing the way the brain and nervous system respond to pain.
Kratom - More Interactions
Kratom interacts with 967 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
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Drug descriptions are provided by MedlinePlus.