SNRIs: A Pharmacological Comparison

What do you think of this article?

Average: 5 Votes 1

Your vote:

By Dr. David Woo - November 11, 2024

Selective serotonin and norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressant medications commonly used to treat mental health disorders such as depression, anxiety, and other related conditions. These medications can sometimes be confused with the similarly named selective serotonin reuptake inhibitors (SSRIs). However, there are crucial distinctions between them when it comes to best treatment practices and side effects.

Understanding the differences between SNRIs, SSRIs, and alternative drug-free depression therapies like transcranial magnetic stimulation (TMS) can help patients and caregivers make informed decisions about treatment. At Madison Avenue TMS & Psychiatry, we help people in the New York area overcome their mental health issues, and that starts with an understanding of what each therapy can offer. This article will explore the effectiveness of SNRIs, their risks, and how they compare to other treatment options.

Jump to:

The Difference Between SNRI And SSRI Drugs

How they work

SNRIs and SSRIs are both types of antidepressants. As their names suggest, they both work on serotonin. Serotonin is a neurotransmitter—a type of chemical that helps transmit signals in the brain. It plays a key role in regulating mood, emotions, and other functions such as sleep, appetite, and digestion. Low levels of serotonin are often linked to depression, as they affect mood stability and feelings of well-being.

SSRIs target serotonin alone, increasing its levels in the brain by blocking its reuptake. The theory behind these antidepressants is that, by increasing serotonin levels in the brain, they improve communication between brain cells and alleviate symptoms of depression.
SNRIs affect both serotonin and norepinephrine. Norepinephrine is another neurotransmitter that plays a vital role in regulating mood, attention, and the body’s stress response. It is related to our “fight or flight” response, impacting heart rate, blood pressure, and energy levels. In terms of depression, low levels of norepinephrine are linked to feelings of lethargy, lack of focus, and a diminished ability to handle stress. SNRIs increase norepinephrine, making them more versatile for conditions involving energy levels and concentration, such as attention-deficit hyperactivity disorder (ADHD) and anxiety.

Am I Taking An SSRI Or SNRI?

If you’re unsure which medication you are taking, check the label and brand name.

SSRI list of common medications:

Fluoxetine (Prozac)
Sertraline (Zoloft)
Escitalopram (Lexapro)
Paroxetine (Paxil)

SNRI list of common medications:

Venlafaxine (Effexor)
Duloxetine (Cymbalta)
Desvenlafaxine (Pristiq)
Levomilnacipran (Fetzima)

Conditions Treated

The distinctive chemical interactions of SSRIs and SNRIs make them more suitable for treating different symptoms, even if they are both used for depression and anxiety.

SSRIs are commonly prescribed for depression, anxiety, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD).
SNRIs are prescribed for depression, generalized anxiety disorder (GAD), ADHD, PTSD, and chronic pain conditions like fibromyalgia.

Side Effects

Side effects are a major issue in both types of antidepressants, although the different chemical effects of each medication mean that certain side effects can be more likely with SSRIs or SNRIs.

SSRI side effects include nausea, weight gain, and sexual dysfunction.

SNRI side effects can include similar side effects as SSRIs. However, the increased norepinephrine may also cause increased heart rate and blood pressure. Other side effects associated with SNRIs include:

Constipation (a commonly reported SNRI side effect)
Increased sweating
Insomnia
Dry mouth
Memory loss
Hypertension (in some patients).

Side effects vary in frequency, intensity, and prevalence, but they are widely felt enough to seriously impact medication adherence, making antidepressants ineffective as a treatment for some people (1, 2, 3, 4).

Not everyone reacts to medication in the same way, which is why we recommend regular consultations with a psychiatric professional to find the best one for you.

Madison Avenue TMS & Psychiatry offers medication management services for individuals in the NYC area taking SSRIs, SNRIs, or other psychiatric medications. These consultations, conveniently accessible via telehealth, help monitor your medications’ effectiveness and adjust the type of drug or dosage as necessary.

Effectiveness Of SNRIs

Recent studies show that SNRIs can be highly effective for treating various conditions. In particular, they are prescribed to patients where anxiety symptoms are more significant and in cases where mental symptoms are also combined with physical pain or fatigue. The dual-action mechanism makes them suitable for patients with complex symptom profiles, such as combined anxiety and depression.

Advantages of SNRI vs. SSRI medications

Symptom relief: SNRIs may provide broader symptom relief, especially when physical symptoms like chronic pain are present alongside mood disturbances.
Energy and motivation: SNRIs can be more beneficial for patients experiencing low energy and motivation due to their effect on norepinephrine, making them a good option for ADHD and fatigue-related depression.

Summing Up: SSRI vs. SNRI Comparison Table

Feature	SSRIs (Selective Serotonin Reuptake Inhibitors)	SNRIs (Serotonin and Norepinephrine Reuptake Inhibitors)
Mechanism of Action	Increases serotonin levels by blocking reuptake	Increases both serotonin and norepinephrine by blocking reuptake
Conditions Treated	Depression, anxiety, PTSD, OCD	Depression, anxiety, PTSD, ADHD, chronic pain
Common Medications	– Fluoxetine (Prozac)	– Venlafaxine (Effexor)
	– Sertraline (Zoloft)	– Duloxetine (Cymbalta)
	– Escitalopram (Lexapro)	– Desvenlafaxine (Pristiq)
Side Effects	Nausea, weight gain, sexual dysfunction	Similar to SSRIs + potential for increased heart rate, high BP
Energy and Motivation Impact	Typically neutral or sedative effect	May increase energy and focus, beneficial for ADHD
Withdrawal Symptoms	Can be significant (discontinuation syndrome)	Often more intense due to dual neurotransmitter action
Effectiveness	Effective for mood and anxiety disorders	Effective for mood disorders with additional benefits for pain and concentration
Best for	Primary mood disorders like depression and anxiety	Depression with additional symptoms like fatigue or chronic pain

What If Medication Doesn’t Work? Exploring Alternative Therapies

For people who don’t respond to medications, there are other treatment options available that can offer long-term relief from symptoms even when antidepressants or other drugs have failed.

Transcranial magnetic stimulation (TMS) is a non-invasive therapy that uses magnetic pulses to stimulate nerve cells in the brain. TMS has been shown to be effective for patients who have not responded well to antidepressants, including both SSRIs and SNRIs. It can provide symptom relief for depression, anxiety, OCD, and other related conditions without the systemic side effects associated with medication.

Ketamine therapy for depression is delivered via an FDA-approved nasal spray (esketamine). With a controlled dose delivered in a clinical setting, ketamine offers fast-acting relief for particularly acute cases of depression.

Medication Management And TMS In NYC

If you or a loved one are struggling with mental health issues, Madison Avenue TMS & Psychiatry is here to help. Our team is dedicated to providing compassionate care that empowers patients to take control of their mental health, including medication management and alternatives such as TMS and ketamine therapy. Contact us online today or call (212) 731-2033 to schedule a consultation and take the first step toward a brighter future.

More about depression medications:

Sources:

Marks, S. A clinical review of antidepressants, their sexual side-effects, post-SSRI sexual dysfunction, and serotonin syndrome. British Journal of Nursing. 2023;32(14), 678. Link. Accessed October 19, 2024.
Pillinger, Toby et al. Antidepressant and antipsychotic side-effects and personalised prescribing: a systematic review and digital tool development. The Lancet Psychiatry. 2023;10(11), 860 – 876. Link. Accessed October 19, 2024.
Niarchou, E., Roberts, D. L., & Naughton, B. D. (2024). What is the impact of antidepressant side effects on medication adherence among adult patients diagnosed with depressive disorder: A systematic review. Journal of Psychopharmacology. Link. Accessed October 19, 2024.
Braund TA, Tillman G, Palmer DM, Gordon E, Rush AJ, Harris AWF. Antidepressant side effects and their impact on treatment outcome in people with major depressive disorder: an iSPOT-D report. Transl Psychiatry. 2021;;11(1):417. Link. Accessed October 19, 2024.
Han EH, Kim H, Lee KJ. Comparison of Effect of SSRIs and SNRIs on Depression, Pain and Somatic Symptoms in Elderly Patients with Major Depressive Disorder. Korean Journal of Psychosomatic Medicine.. 2020 Jun 30;28(1):72–80. Link. Accessed October 19, 2024.
Stefánsdóttir, Í. H., Ivarsson, T., & Skarphedinsson, G. Efficacy and safety of serotonin reuptake inhibitors (SSRI) and serotonin noradrenaline reuptake inhibitors (SNRI) for children and adolescents with anxiety disorders: a systematic review and meta-analysis. Nordic Journal of Psychiatry. 2023;77(2), 137–146. Link. Accessed October 19, 2024.
Ferreira G E, Abdel-Shaheed C, Underwood M, Finnerup N B, Day R O, McLachlan A et al. Efficacy, safety, and tolerability of antidepressants for pain in adults: overview of systematic reviews. BMJ 2023; 380. Link. Accessed October 19, 2024.

Dr. David Woo

Dr. David Woo is the owner and head clinical psychiatrist at Madison Avenue TMS and Therapy in New York City. Dr. Woo has been seeing patients in private practice since 2002, always with the goals of combining evidence-based medicine with psychodynamic psychotherapy and collaborating with other mental health professionals to ensure the best possible outcomes for his patients. He has been certified to administer TMS at his practice since 2017. His greatest clinical interests include helping patients suffering from depression, anxiety, and obsessive compulsive disorder.

Follow Dr. Woo On