What's the Difference?

SNRI (Serotonin-Norepinephrine Reuptake Inhibitors) and SSRI (Selective Serotonin Reuptake Inhibitors) are two classes of antidepressant medications commonly prescribed to treat depression and anxiety disorders. While both medications work by increasing the levels of certain neurotransmitters in the brain, they differ in their mechanism of action. SNRIs, as the name suggests, inhibit the reuptake of both serotonin and norepinephrine, leading to increased levels of these neurotransmitters in the brain. On the other hand, SSRIs primarily target the reuptake of serotonin only. This distinction can result in different therapeutic effects and side effects for individuals. Additionally, SNRIs are often considered to have a broader spectrum of action, potentially providing relief for symptoms such as chronic pain or fatigue, which are associated with low norepinephrine levels. Ultimately, the choice between SNRI and SSRI depends on the individual's specific symptoms and needs, and should be made in consultation with a healthcare professional.


ClassSerotonin-Norepinephrine Reuptake InhibitorSelective Serotonin Reuptake Inhibitor
Mode of ActionInhibits reuptake of serotonin and norepinephrineInhibits reuptake of serotonin
Primary UseTreats depression, anxiety, and certain pain disordersTreats depression, anxiety, and certain other mental health conditions
Common MedicationsVenlafaxine, DuloxetineFluoxetine, Sertraline, Escitalopram
Side EffectsNausea, dizziness, insomnia, increased blood pressureNausea, headache, sexual dysfunction, weight gain
Withdrawal SymptomsDizziness, fatigue, flu-like symptomsDizziness, nausea, anxiety, electric shock sensations

Further Detail


When it comes to treating mental health conditions such as depression and anxiety, selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are two commonly prescribed classes of medications. While both SNRIs and SSRIs work by increasing the levels of certain neurotransmitters in the brain, they have some distinct differences in terms of their mechanisms of action, side effects, and efficacy. In this article, we will explore the attributes of SNRIs and SSRIs to help you understand their similarities and differences.

Mechanism of Action

SSRIs, as the name suggests, primarily target the reuptake of serotonin, a neurotransmitter associated with mood regulation. By inhibiting the reuptake of serotonin, SSRIs increase its availability in the brain, leading to improved mood and reduced symptoms of depression or anxiety. On the other hand, SNRIs target both serotonin and norepinephrine reuptake. Norepinephrine is another neurotransmitter involved in mood regulation, as well as the body's stress response. By inhibiting the reuptake of both serotonin and norepinephrine, SNRIs provide a dual mechanism of action, potentially offering a broader spectrum of therapeutic effects.


Both SNRIs and SSRIs are commonly prescribed for the treatment of major depressive disorder (MDD) and generalized anxiety disorder (GAD). However, SNRIs are also approved for the treatment of other conditions such as fibromyalgia, diabetic peripheral neuropathy, and chronic musculoskeletal pain. This broader range of indications for SNRIs may make them a preferred choice for individuals with comorbid conditions or specific pain-related symptoms.

Side Effects

Like any medication, both SNRIs and SSRIs can cause side effects. However, the specific side effects may vary between the two classes of drugs. Common side effects of SSRIs include nausea, diarrhea, headache, sexual dysfunction, and sleep disturbances. On the other hand, SNRIs may also cause similar side effects but are more likely to be associated with increased blood pressure and heart rate due to their effect on norepinephrine. Additionally, SNRIs may have a higher risk of causing withdrawal symptoms if abruptly discontinued, compared to SSRIs.


When it comes to the efficacy of SNRIs and SSRIs, studies have shown that both classes of medications can be effective in treating depression and anxiety disorders. However, individual responses to these medications can vary, and finding the right medication and dosage may require some trial and error. Some studies suggest that SNRIs may have a slight advantage in terms of efficacy for certain individuals, particularly those with more severe depression or anxiety symptoms. However, it is important to note that the overall differences in efficacy between SNRIs and SSRIs are relatively modest.

Drug Interactions

Both SNRIs and SSRIs can interact with other medications, potentially leading to adverse effects or reduced efficacy. It is important to inform your healthcare provider about all the medications, supplements, and herbal products you are taking before starting either of these medications. SNRIs, due to their effect on norepinephrine, may have more significant interactions with medications that affect blood pressure or heart rate. SSRIs, on the other hand, may have interactions with medications that increase the risk of bleeding, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or anticoagulants.

Discontinuation Syndrome

Both SNRIs and SSRIs can cause discontinuation syndrome if abruptly stopped or rapidly tapered. Discontinuation syndrome is characterized by various physical and psychological symptoms such as dizziness, nausea, headache, irritability, and flu-like symptoms. However, SNRIs may have a higher risk of causing discontinuation syndrome compared to SSRIs, possibly due to their dual mechanism of action and shorter half-lives. It is important to work closely with your healthcare provider when discontinuing either of these medications to minimize the risk of withdrawal symptoms.


In conclusion, SNRIs and SSRIs are two classes of medications commonly used for the treatment of depression and anxiety disorders. While both classes work by increasing the levels of certain neurotransmitters in the brain, SNRIs provide a dual mechanism of action by targeting both serotonin and norepinephrine reuptake. This broader mechanism may offer advantages in certain individuals or conditions. However, the choice between SNRIs and SSRIs should be based on individual factors such as comorbid conditions, specific symptoms, and potential side effects. It is essential to work closely with a healthcare provider to find the most suitable medication and dosage for your specific needs.

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