Originally published May 2018. Reviewed and substantially revised August 2026.

Your genetics decide your eye colour and your height. They also influence how your body processes medications — which is part of why one person does well on a particular antidepressant while another feels awful on the same dose, and why some people tolerate a statin while others get muscle aches.

The science that studies this is called pharmacogenomics, often shortened to PGx. It is real and genuinely useful. It is also frequently oversold, including in the earlier version of this article — so here is a straighter account.

What pharmacogenomic testing can actually do

For a specific and fairly short list of gene–drug pairs, there is solid evidence linking a genetic variant to how you handle a particular medication, with clear guidance on what to do about it. Well-established examples include certain genes affecting:

• how quickly you activate or clear some pain medications
• your risk of muscle side effects from certain statins
• how you metabolise some blood thinners and heart medications
• your risk of severe reactions to a handful of specific drugs

Where that evidence exists, testing can genuinely change a prescribing decision — usually by flagging a medication or dose to avoid rather than by naming the one drug that will work.

What it cannot do

The earlier version of this article said we could test you and “determine which antidepressant is correct for you,” and that it “takes the guessing out of prescribing.” That went too far, and we’re correcting it.

In late 2018 the FDA issued a safety communication specifically warning that claims like that are not supported by the evidence — that for most medications, genetic tests have not been shown to predict which drug will work for a given patient, and that changing treatment on the basis of such claims can cause harm.

Choosing an antidepressant still depends on your symptoms, your history, what you’ve tried before, other conditions you have, side effects you can live with, and cost. Genetics can be one input. It is not the answer.

So is it worth doing?

Sometimes — and it is worth a conversation rather than a blanket yes or no. It tends to be most useful when you have already had a bad or unusual reaction to a medication, when you are on a drug with a well-studied gene interaction, or when standard treatment hasn’t worked and we’re trying to understand why.

Coverage varies a great deal between plans and tests, so ask about cost before testing. See our Insurance & Billing page or just ask us.

Talk to us

If a medication hasn’t worked the way it should, or you’ve had side effects that seem out of proportion, that is worth discussing regardless of whether testing turns out to be the right tool. Call (417) 332-3639.

As always, I hope you stay healthy and happy.

Carolyn Clark, NP-C