Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Thioridazine is an older phenothiazine antipsychotic that blocks dopamine D2 and many other receptors. It was widely used for schizophrenia, but because it lengthens the QT interval of the heartbeat more than most antipsychotics, it is now reserved for people who have not responded to others, and has been withdrawn in many countries. It was sold as Mellaril.
Thioridazine is broken down mainly by CYP2D6. People with little or no CYP2D6 activity reach higher levels, with a greater effect on the heart rhythm, and the US label states that it is contraindicated in people known to have reduced CYP2D6 activity; the US FDA lists the pair. There is no CPIC or DPWG guideline.
Clinical guidelines that name a gene for Thioridazine. They sort people into groups by the gene copies they carry.
US FDA: CYP2D6. CYP2D6 activity score 0 to 1.
US FDA: CYP2D6. CYP2D6 activity score 0. Data that Support Therapeutic Management Recommendations.
Every published finding on gene variants and Thioridazine. 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.
CYP2D6 rs1080985: Level 3. Other. 1.
Studies of how quickly the body processes this medication.
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
Antipsychotics (class) (Antipsychotics)
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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