*I am not a medical doctor, and this article is not meant to provide a diagnosis or treatment. The content is for informational and educational purposes only. Always consult a licensed healthcare provider regarding any questions you have about symptoms, medications, or your mental or physical health.

What Are SSRIs and SNRIs?

SSRIs and SNRIs are two of the most common medications used to treat depression and anxiety. They work on the brain’s neurotransmitters, which are chemical messengers that influence mood, stress response, sleep, energy, and even pain. Although they sound similar, they act differently in the brain, and those differences matter (Stahl, 2005; Strawn et al., 2023).

SSRIs, or selective serotonin reuptake inhibitors, work by increasing the amount of serotonin, a neurotransmitter often linked to mood, available in the brain. SNRIs, or serotonin-norepinephrine reuptake inhibitors, increase both serotonin and norepinephrine, a chemical involved in alertness, motivation, and pain regulation (Stahl, 2005). These differences affect which symptoms they help most and which side effects are more likely to occur.

How SSRIs Affect the Brain

Serotonin plays a major role in mood, anxiety, sleep, digestion, and emotional regulation. SSRIs increase serotonin availability by slowing its reabsorption into neurons, allowing it to remain active longer (Chu & Wadhawan, 2023).

This process helps regulate mood and anxiety, but it can also cause early side effects like nausea, restlessness, sleep changes, and emotional sensitivity. These typically improve after the first few weeks as the brain adapts (Edinoff et al., 2021).

For teens, SSRIs are the most researched and most commonly recommended first-line medications for depression and anxiety, especially fluoxetine (Prozac) and escitalopram (Lexapro) (Walter et al., 2023; Korczak et al., 2023).

One important insight from research: while SSRIs increase serotonin, they do so gradually, and symptom relief often takes several weeks. This delayed effect is normal and expected (Johnson et al., 2022).

How SNRIs Affect the Brain

SNRIs increase both serotonin and norepinephrine. Norepinephrine is involved in attention, mental energy, focus, and the body’s stress response. Because of this dual action, SNRIs may be helpful when symptoms include low energy, difficulty concentrating, or when depression occurs alongside chronic pain (Rodrigues-Amorim et al., 2020).

However, norepinephrine also influences heart rate, blood pressure, and physical tension. For this reason, SNRIs can cause certain side effects more often than SSRIs, such as increased heart rate, sweating, or activation (Stahl, 2005). These medications also tend to create more intense withdrawal symptoms if doses are missed or stopped too quickly, especially with venlafaxine (Stahl, 2005).

For teens, SNRIs are generally considered second-line options due to higher rates of side effects and a more limited research base (Strawn et al., 2023).

To sum it up...

Although both help regulate mood, the nuances matter:

SSRIs:

• Increase serotonin only

• Often calm anxious thoughts and emotional overwhelm

• Better studied in teens

• Typically have fewer physical side effects

• Often first choice for anxiety disorders and depression

SNRIs:

• Increase serotonin and norepinephrine

• Can help with low energy, focus problems, or chronic pain

• May be more activating

• Can raise heart rate or blood pressure

• Can cause more challenging withdrawal symptoms

• Less evidence in adolescents

A key scientific takeaway is that SNRIs may be more potent for some adults, but in younger populations, tolerability and safety make SSRIs the preferred starting point (Walter et al., 2023).

Why Teens Often Start With SSRIs

Clinical guidelines consistently show that SSRIs have the strongest evidence for safety and effectiveness in children and adolescents (Korczak et al., 2023). They are recommended first because:

• They have been studied far more extensively in teens.

• They carry fewer cardiovascular risks.

• They generally cause fewer discontinuation problems.

• They have strong evidence for treating anxiety, one of the most common teen concerns (Walter et al., 2023).

SNRIs are sometimes used when:

• SSRIs do not provide enough relief

• Symptoms include severe fatigue or concentration problems

• There is chronic pain in addition to depression or anxiety

• A teen has responded well to an SNRI in the past

The choice depends heavily on symptoms, medical history, and side-effect sensitivity.

What the Science Shows, in Simple Terms

Peer-reviewed research gives us several consistent findings:

First, SSRIs are typically better tolerated than SNRIs and are associated with fewer cardiovascular side effects (Strawn et al., 2023).

Second, SNRIs are more activating and can be especially helpful for individuals whose depression includes fatigue or physical pain symptoms (Rodrigues-Amorim et al., 2020).

Third, venlafaxine (an SNRI) has shown higher rates of suicidal thoughts or behaviors in some adolescent studies compared to placebo or certain SSRIs, making close monitoring essential (Boaden et al., 2020).

Fourth, all antidepressants can increase suicidal thoughts in teens early in treatment, especially in the first few weeks or after dose changes (Walter et al., 2023). This risk requires careful monitoring from both family and clinicians.

Finally, the combination of medication plus therapy works better than medication alone for most teens (Korczak et al., 2023).

These insights help explain why clinicians are thoughtful and cautious when choosing the right medication for each teen.

How Teens Can Use This Information

Understanding how these medications work allows teens and parents to better recognize patterns and discuss symptoms clearly with clinicians. A few ways to apply this knowledge:

• Track symptoms weekly, especially mood, sleep, focus, irritability, and physical symptoms.

• Notice activation symptoms, such as feeling agitated, restless, or unusually energetic, and report them promptly.

• Pay attention to timing, especially whether symptoms improve or worsen during dose increases or decreases.

• Discuss any chronic pain, as this may influence the choice between SSRI and SNRI.

• Share any personal or family medication history, especially what helped or caused problems.

Most importantly, needing medication does not mean you are weak or broken. These medications work on real biological pathways in the brain, and choosing the right one is part of understanding how your mind and body function.

Key Takeaways

SSRIs and SNRIs both help regulate mood, but they do so in different ways. SSRIs increase serotonin and are generally the first choice for teens because they have the strongest research evidence and tend to be easier to tolerate. SNRIs increase both serotonin and norepinephrine, making them useful for certain symptoms like low energy or chronic pain but also more likely to cause physical side effects. Understanding your symptoms and tracking them carefully can help you and your healthcare provider determine which medication may be right for you.

References

Boaden, K., et al. (2020). Antidepressants in children and adolescents: Meta-review. Frontiers in Psychiatry, 11, 717.

Chu, A., & Wadhawan, S. (2023). Selective serotonin reuptake inhibitors. In StatPearls. NCBI Bookshelf.

Edinoff, A. N., et al. (2021). Selective serotonin reuptake inhibitors and adverse effects. Neurology International, 13(3), 387–407.

Johnson, C. F., et al. (2022). Dose–response effects of SSRIs in depression. BMJ Medicine, 1(1), e000017.

Korczak, D. J., et al. (2023). Diagnosis and management of depression in adolescents. CMAJ, 195(21), E739–E749.

Rodrigues-Amorim, D., et al. (2020). Efficacy, safety, and tolerability of duloxetine: A systematic review. Clinical Psychopharmacology and Neuroscience, 18(3), 381–401.

Stahl, S. M. (2005). SNRIs: Pharmacology, clinical efficacy, and tolerability. CNS Spectrums, 10(9), 732–747.

Strawn, J. R., et al. (2023). Adverse effects of antidepressant medications and their management. Pharmacotherapy, 43(1), 35–60.

Walter, H. J., et al. (2023). Clinical practice guideline for assessment and treatment of children and adolescents with depressive disorders. Journal of the American Academy of Child & Adolescent Psychiatry.