Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Morphine is the classic opioid pain medicine, the main active substance in opium. It acts on mu opioid receptors in the brain and spinal cord to relieve severe pain, after surgery, in cancer and in palliative care, and it eases breathlessness at the end of life. It is sold as MS Contin and MST, among other names.
Morphine is not broken down by CYP2D6, so it is not affected the way codeine is. It is cleared mainly by UGT2B7 into two forms, one of them active, and taken into the liver by the transporter SLC22A1 (OCT1). The most studied genes are OPRM1, the receptor it acts on, COMT, ABCB1 and UGT2B7, mostly for how much morphine people needed for pain relief; the results are mixed. There is no CPIC or DPWG guideline.
Every published finding on gene variants and Morphine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
OPRM1 rs1799971: Level 3. Dosage: Pain, Pain, Postoperative. 16.
COMT rs4680: Level 3. Dosage: Pain, Pain, Postoperative. 9.
OPRM1 rs1799971: Level 3. Efficacy: Pain, Pain, Postoperative. 5.
COMT rs4680: Level 3. Efficacy: Pain. 4.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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