Pharmacogenomic-guided prescribing

Domain IX · Biomedical, neuro & digital

What it is

Pharmacogenomic (PGx)-guided prescribing means that a prescriber uses a person's genotype for selected genes, mostly drug-metabolising enzymes such as CYP2D6 and CYP2C19 and, for some drugs, immune genes such as HLA-B, as one input when choosing a medicine or adjusting how it is used. The idea of…

Format

• Deciding whether to test. No consensus says who should be tested. The ISPG states that current guidelines give no advice on when, or to whom, testing should be offered, and that CYP2C19 and CYP2D6 information is likely most useful for people who had an inadequate response to, or adverse reaction…
• Session count and format. None applies; a test is usually ordered once and the result kept in the record. In therapy, PGx work typically occupies parts of a few sessions: when testing is being considered, when results arrive, and when a medication change is under discussion.

Who practises it, and how they are trained or regulated

• Regulatory status (as of October 2026). In the US most PGx tests have not been reviewed by the FDA or another regulator for their clinical claims; CLIA oversight does not evaluate those claims before tests reach the market. In November 2018 the FDA warned that many tests claiming to predict response to specific medicines had not been reviewed, and that acting on them could lead to inappropriate treatment decisions.…

Evidence status, as the guide reports it

• Evidence status (as sources state it).

Questions to explore with your client

• What drew you to it, and what are you hoping it will change?
• Does it involve any substance, plant preparation, remedy or supplement? Has your doctor or prescriber been told, especially about any medication you take?
• Does it involve fasting, a special diet or 'detox'? Have you discussed this with your doctor?
• Is it a group, retreat or community? How do they respond if someone wants to leave or raises a concern?
• How do you and the practitioner understand what is happening, in spiritual or cultural terms? Is that a source of comfort, worry, or both?
• Who runs it, and what training or registration do they hold?
• What actually happens in a session or meeting, and how often?
• What does it cost, and is there pressure to commit to more?
• How do you feel afterwards, in the hours and days that follow?
• Does it fit with, or clash with, the work we do here?

What practitioners of it watch for

• letters that read as advocacy for a test or a drug.
• attributing all progress or setbacks to the medicine choice.
• your own enthusiasm or scepticism leaking in; stay with what the sources say.
• a result being used to justify giving up on all treatment, including therapy.
• decisions made under pressure from marketing or family; slow down and return to values.

When to involve someone else

• New or worsening physical symptoms, or advice to stop or change prescribed medication: involve the client's doctor or prescriber.
• Signs of coercion, isolation from family and friends, escalating costs or secrecy: discuss openly and consider safeguarding.
• A crisis or thoughts of suicide: follow your crisis protocol. In the US, call or text 988; in the UK and Ireland, Samaritans on 116 123.

Drawn automatically from the guide's own sections. Stay curious: neither endorse nor dismiss what the client values, and check anything that matters against the full guide and its sources. Not medical advice.