Is GeneSight Testing Worth It? What Genetic Testing Can and Can't Tell You

Imagine receiving a genetic testing report that sorts psychiatric medications into green, yellow, and red categories. The antidepressant you've been taking for two years is sitting in the red column.

It's hard to look at that and not wonder whether you've been taking the wrong medication all along.

I've had patients come in convinced that their genetic testing results finally explain why previous treatments failed, or that the report can tell us exactly which medication to prescribe next.

Unfortunately, it isn't that simple.

Pharmacogenomic testing, commonly associated with brands like GeneSight, can provide useful information about how your body processes certain medications. What it cannot reliably tell us is which antidepressant will work best for your depression or anxiety.

That distinction matters more than most people realize.

What does genetic testing actually measure?

Pharmacogenomic testing examines variations in genes that influence how your body responds to medications.

Some of the most clinically useful findings involve liver enzymes, particularly CYP2D6 and CYP2C19, which help metabolize many commonly prescribed antidepressants.

Depending on your genetic makeup, you may process certain medications more slowly or more quickly than expected.

For example, someone who metabolizes escitalopram (Lexapro) slowly may develop higher medication levels at a standard dose, potentially increasing side effects. Someone who processes it unusually quickly may have lower medication exposure, potentially affecting its effectiveness.

These differences can help explain why one person experiences significant side effects on a relatively low dose while another tolerates much higher doses without difficulty.

This is where genetic testing has legitimate clinical value. Established pharmacogenomic guidelines can help clinicians make decisions about dosing, monitoring, or selecting an alternative medication.

But metabolism is only part of the story.

What genetic testing cannot predict

This is where the marketing can get ahead of the science.

A genetic test cannot reliably tell us whether Prozac will relieve your depression, whether Zoloft will help your anxiety, or whether Vyvanse will work better than Focalin for your ADHD.

Some testing panels go beyond medication metabolism and include genes associated with how medications act in the brain. These findings are sometimes presented as predictions about medication effectiveness, but the supporting evidence is much less established.

For example, a patient might receive a report suggesting that Focalin (dexmethylphenidate) is less likely to be effective because of a variation in a gene called ADRA2A, which is involved in norepinephrine signaling. Meanwhile, Vyvanse (lisdexamfetamine) may appear to have no identified genetic concerns.

It’s understandable to conclude that Vyvanse is the better choice. But that’s not what the results actually tell us.

The association between ADRA2A and response to methylphenidate-based stimulants is inconsistent and not sufficiently validated to guide medication selection. And the absence of an identified genetic marker for Vyvanse doesn’t predict a better response. It simply means the test has less relevant genetic information to offer about that medication.

In other words, we’re not comparing two medications using equally reliable evidence.

The same limitation applies to some genetic markers used to predict antidepressant effectiveness. The Clinical Pharmacogenetics Implementation Consortium (CPIC), which develops evidence-based prescribing guidelines, specifically does not recommend using two commonly tested genes, SLC6A4 and HTR2A, to select antidepressants because the evidence is insufficient.

Depression, anxiety, and ADHD are complicated conditions involving genetics, neurobiology, environment, medical history, and individual experiences. A cheek swab cannot capture all of that.

A medication appearing in the green category doesn’t mean it will work. And a medication appearing in the red category doesn’t necessarily mean it won’t.

Does genetic testing actually improve treatment outcomes?

Research suggests that pharmacogenomic testing may offer some benefit, particularly for patients who have already struggled with medication trials. But the improvements are considerably smaller than many people expect.

In the large PRIME Care study, published in JAMA in 2022, nearly 2,000 patients with depression participated in a randomized trial of pharmacogenomic-guided prescribing.

Clinicians who received genetic testing results were more likely to prescribe medications without predicted gene-drug interactions. Patients in that group also experienced a modest improvement in remission rates early in treatment.

However, by 24 weeks, the difference in remission between the groups was no longer statistically significant.

Other studies have shown similarly modest benefits.

My interpretation is that genetic testing may help us avoid certain medication-related problems and make more informed prescribing decisions. It doesn't eliminate the trial-and-error process of psychiatric treatment.

The biggest misunderstandings I see

"My medication is in the red. I shouldn't be taking it."

Not necessarily. A red classification may indicate that you metabolize the medication differently or that a dose adjustment or closer monitoring could be appropriate. It does not automatically mean the medication is unsafe or ineffective.

If you've been doing well on a medication for years, your actual response matters more than the color assigned to it.

"This medication is green, so it should work for me."

Green generally means the test hasn't identified a significant gene-drug concern. It does not predict whether the medication will successfully treat your symptoms.

"The test says I metabolize medications normally, so why am I having side effects?"

Because genetics is only one factor. Other medications, drug interactions, individual sensitivity, and medical conditions can all affect how someone responds to treatment. You can metabolize a medication normally and still experience significant side effects.

When is GeneSight testing worth considering?

I don't routinely recommend pharmacogenomic testing before someone starts their first antidepressant. We can usually make a reasonable initial medication choice based on symptoms, medical history, previous treatment, side-effect concerns, and patient preferences.

I find genetic testing more useful when someone has experienced repeated medication failures, unexpected side effects at low doses, or unusually poor responses despite adequate dosing.

It can also be helpful when multiple medications are involved and we're trying to understand possible interactions.

Even then, I use the results as one piece of clinical information rather than a treatment plan.

And if you've already had testing done, keep a copy. Your inherited genetic variants generally don't change, and some findings may be relevant to medications prescribed outside psychiatry.

A few questions I get

How much does GeneSight cost, and will insurance cover it?

According to GeneSight, people with Medicare Part B or Medicaid typically pay nothing, and most people with commercial insurance or no insurance pay $330 or less. They also offer an interest-free payment plan and income-based financial assistance. Coverage varies a lot from plan to plan, so check before you swab, not after the bill arrives.

Should I stop a medication that came back red?

No, not on your own. If the medication is working and you're tolerating it, that's the result that counts. Stopping an antidepressant abruptly can cause withdrawal symptoms and relapse. Bring the report to your prescriber and go through it together.

Will I ever need to repeat the test?

Generally not. The inherited variants it measures don't change. What does change is everything around them. Fluoxetine (Prozac), paroxetine (Paxil), and bupropion (Wellbutrin) all strongly block CYP2D6, so someone with normal CYP2D6 genes can process certain medications like a slow metabolizer while taking one of them. The report doesn't know what else you're taking. Your prescriber has to put that together.

My take

I think pharmacogenomic testing has a place in psychiatric care, but I worry about the expectations surrounding it.

Patients who have struggled through multiple medication trials understandably want an explanation. More than that, they want reassurance that the next medication will finally be the right one.

Genetic testing can sometimes explain why a medication caused unexpected side effects or didn't achieve the anticipated blood levels. That's useful information, and in certain situations, it can influence what I prescribe.

But it cannot tell us whether a medication will make you feel better.

The most useful question to ask isn't, "Which antidepressant does my genetic test say I should take?"

It's, "Can these results help us understand what happened with the medications I've already tried?"

That's a much better use of the science.

This article is for general information and is not a substitute for individual medical advice. Do not start, stop, or change a prescription without talking to your prescriber.