How Do Antidepressants Work?

Depression, one of the most prevalent mental health conditions, is often treated with medications called antidepressants.

In fact, according to the Centers for Disease Control and Prevention, “antidepressants are one of the three most commonly used therapeutic drug classes” in the U.S. The agency estimates that nearly 13 percent of persons over age 12 take antidepressants.

But have you ever stopped to wonder how antidepressants work?

Antidepressants balance your brain’s levels of neurotransmitters, which are the chemicals and circuitry that determine mood and reaction to new information. How antidepressants rebalance these chemicals is complicated and depends on your unique genetic code.

How Antidepressants are Processed by Your Body

First, let’s look at the four stages during which your body converts an antidepressant into an active agent to help fight depression:

1. Absorption: When medication is taken orally, it travels through your small and large intestines to the liver.
2. Distribution: After passing through the liver, the antidepressant enters the bloodstream. The drug molecule interacts with various protein and fat molecules in the bloodstream, which can affect distribution. During this process the medication starts to take effect.
3. Metabolism: In this phase liver starts chemically modifying the medication to make it more water soluble and eventually eliminate from the body. The rate of metabolism affects level of the medication in the body.
4. Excretion: What remains of the antidepressant is discarded by the body.

Your Metabolism Plays an Important Role

Metabolism is often thought about in terms of how a person gains or loses weight. However, your metabolism also is crucial to how medications and antidepressants are processed by your body.

Importantly, it’s not a one-size-fits-all approach with metabolism and medication: Your metabolism may vary based on the kind of antidepressant you take. For example, you may have metabolize one medication quickly and another medication more slowly.

Your rate of metabolism is important for two reasons.

1. If your metabolism is fast for one kind of medication, it spends too little time in your body and will likely not be an effective treatment.
2. If your metabolism is slow for another kind of medication, it can spend too much time in your body, resulting in unintended side effects.

Your metabolism is one of the main reasons why a certain antidepressant medication may not have worked for you in the past. If you’ve gone through a lengthy trial-and-error process, you know how frustrating that can be.

Genetic testing can inform your doctor about genes that may impact how you metabolize or respond to certain depression medications, which can help your clinicians determine how to best treat your depression. If you have had unfavorable results with an antidepressant and are experiencing unmanageable side effects, ask your healthcare provider about the GeneSight^® test.

For more details, check out our full infographic on how your body metabolizes antidepressants.