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SSRIs vs SNRIs: What Is the Difference and Which One Should I Take?

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If you suffer from anxiety or depression, you’ve probably heard about SSRIs and SNRIs. 

Though both drug types are clinically effective at treating depression and anxiety, there are differences between the two that might make one option more suitable for treating your particular depression or anxiety symptoms. 

In this article, we’ll discuss both types of antidepressants so you can better understand the pros and cons of each treatment. At Klarity, we know that finding the right medication takes some time and a “trial and error” approach to different medications.

The medical providers on Klarity are depression and anxiety specialists who can help you find the right treatment fast—no waiting months to be seen or spending hours of your day commuting to in-network providers.

Klarity has already helped 30,000+ people find online depression, anxiety, ADHD, and insomnia treatment. Whether you are looking to switch medications and try a different treatment route, or are exploring medication for the first time, the medical providers on Klarity are ready to help you within 48 hours.

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This article discusses suicide, suicidal ideation, and self-harm. If you or someone you know is experiencing suicidal thoughts or is in crisis, contact the Suicide Prevention Lifeline immediately at 800-273-8255.

About SSRIs and SNRIs 

SSRIs (selective serotonin reuptake inhibitors) and SNRIs (serotonin and norepinephrine reuptake inhibitors) have both been shown to be effective treatments for depression and anxiety. 

Both of these medications address chemical imbalances that cause both mental health conditions, but there are several differences you must understand in order to make an informed decision regarding depression or anxiety treatment. 

SSRIs (Selective Serotonin Reuptake Inhibitors)

SSRIs are one of the most commonly prescribed forms of antidepressants and have proven to be considerably effective at treating mild to severe depression symptoms. They are relatively safe, typically causing fewer side effects than other antidepressants. 

Medical providers often choose SSRIs like fluoxetine (Prozac), sertraline (Zoloft), and escitalopram (Cipralex) to treat depression.

How Do SSRIs Work?

SSRIs work by altering how the brain uses the neurotransmitters serotonin and dopamine. The medication blocks the reabsorption of these neurotransmitters, making the concentration higher in the spaces between brain cells (neurons). 

When the concentration of neurotransmitters is brought back into balance, brain cells are better able to communicate with one another. 

Serotonin is responsible for several important bodily functions, including:

  • Mood
  • Digestion
  • Sleep
  • Wound healing
  • Sexual function
  • Nausea

Dopamine is responsible for other bodily functions, including:

  • Memory
  • Pleasure
  • Learning
  • Attention
  • Motivation

When these neurotransmitter levels are too low, it can cause certain symptoms of depression and anxiety. Because SSRIs elevate serotonin and dopamine levels over time, they are effective at treating symptoms of anxiety and depression.

What Do SSRIs Treat?

SSRIs are most commonly thought of as a depression treatment, but they can be effective at treating other conditions as well.


Depression (major depressive disorder or MDD) is a mood disorder that affects the way you think and feel, causing sadness, apathy, and exhaustion. With MDD, these emotions negatively impact a person’s quality of life. If untreated, depression can lead to a number of physical, emotional, and behavioral problems. 

Depression symptoms include:

  • Feeling sad or tearful
  • Feeling empty and hopeless
  • Feeling irritable and angry when there isn’t an obvious trigger
  • Feeling disinterested in hobbies or activities that used to bring joy
  • Sleeping too much or too little
  • Eating too much or too little
  • Anxiety and restlessness 
  • Weight Loss or weight gain
  • Trouble concentrating, thinking, and making decisions
  • Feeling excessively tired
  • Moving or speaking slowly
  • Thoughts of suicide or self-harm
  • Unexplainable physical aches and pains

Many depression symptoms could be the result of serotonin and dopamine imbalances in the brain. Since SSRIs affect neurotransmitters that control mood, motivation, sleep, and pleasure, elevating the number of these neurotransmitters can help reduce depression symptoms.

Anxiety Disorders

There are several anxiety disorders that SSRIs are approved to treat. Generally, people with anxiety disorders experience persistent, intense, and distracting bouts of fear and worry over common situations. 

SSRIs are considered effective in treating the following anxiety disorders:

  • Generalized Anxiety Disorder
  • Panic Disorder
  • Social Anxiety Disorder
  • Post Traumatic Stress Disorder
  • Obsessive-Compulsive Disorder
  • Phobias

Symptoms of anxiety include:

  • Nervousness
  • Restlessness
  • Feeling a sense of impending danger, doom, or panic
  • Increased heart rate
  • Hyperventilation
  • Sweating
  • Shaking
  • Insomnia
  • Difficulty thinking about the present or tasks at hand (work, school, conversations) due to worry
  • Rumination
  • Inability to control thoughts and feelings of worry
  • Exhaustion
  • G.I. Difficulties
  • Avoiding triggers that cause anxiety

Many anxiety symptoms can be caused by an imbalance of serotonin and dopamine since these neurotransmitters are responsible for regulating mood, feelings of well-being, sleep, motivation, and alertness. SSRIs provide a way to regulate the levels of serotonin and dopamine in the brain, reducing anxiety symptoms. 

What Are the Most Commonly Prescribed SSRIs?

The FDA has approved numerous SSRIs for the treatment of depression and anxiety. Some of these medications are prescribed more often than others due to their effectiveness, or their limited side effects. 

Your medical health provider will work with you to determine the best medication for your symptoms. Below are some of the most common SSRIs prescribed by medical providers.

  • Zoloft (sertraline) 
  • Prozac (fluoxetine)
  • Celexa (citalopram)
  • Paxil (paroxetine)
  • Lexapro (escitalopram) 
  • Luvox (fluvoxamine)


SSRIs are relatively inexpensive, with Zoloft and Prozac often costing $40 for 30 tablets. The generic forms of these medications are significantly less expensive and more likely to be covered by insurance.

Common Side Effects

SSRIs may cause side effects. Some of the most common include:

  • Agitation
  • Irritability
  • Anxiety
  • Headaches
  • Loss of appetite and weight loss
  • Increased appetite and weight gain
  • Diarrhea
  • Constipation
  • Dizziness
  • Blurred vision
  • Dry mouth
  • Sweating
  • Feeling too tired or not sleeping well
  • Reduced sex drive
  • Difficulty achieving orgasm
  • Erectile dysfunction

Some people may have an allergic reaction to certain SSRIs, so it’s important to discuss your medical history with your psychiatric healthcare provider before taking these medications. 

Warnings for Use

SSRIs are generally safe, but they pose some risks if misused or taken without following your healthcare provider’s instructions. While SSRIs are typically non-addictive, dependency can occur in some people. 

SSRIs can also react negatively when taken with other medications, including:

  • SNRIs (serotonin-norepinephrine reuptake inhibitors (SNRIs)
  • Lithium, which treats severe depression and bipolar disorder
  • Clozapine and pimozide, which are used to treat schizophrenia and psychosis
  • Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen
  • Some asthma medications, including theophylline – a medicine used to treat asthma
  • Some migraine medications
  • Tricyclic antidepressants
  • Monoamine oxidase inhibitors (MAOIs)

Serotonin Syndrome

In rare cases, SSRIs can lead to serotonin syndrome—an excess buildup of serotonin in the brain. This most often occurs when two medications that raise serotonin levels are taken simultaneously. 

Serotonin syndrome typically happens within a few hours of taking a medication that elevates serotonin levels. These symptoms can include anxiety, high fever, and confusion. Seek immediate medical attention if you show any of these symptoms directly after taking an antidepressant.

Black Box Warning

All antidepressants come with a black box warning. In certain placebo-controlled studies, children and adolescents taking antidepressants reported an increase in suicidal thoughts and ideation compared to the placebo group. Though these findings have not been replicated in adult populations, the FDA requires that issuers of antidepressants disclose these risks. 

SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors)

Selective serotonin-norepinephrine reuptake inhibitors or SNRIs are similar to SSRIs in that they prevent the reuptake of certain neurotransmitters. However, there is a key difference—SNRIs also affect norepinephrine levels in addition to serotonin and dopamine levels.  

SNRIs are effective in relieving many depression symptoms and are also prescribed for certain anxiety disorders.  

How Do SNRIs Work?

Norepinephrine has distinct functions in the human body. Not only is it a neurotransmitter, but it’s also a hormone. It plays a crucial role in mediating your body’s flight-or-fight response. 

Norepinephrine performs the following specific functions: 

  • Increases attention, alertness, and arousal 
  • Constricts blood vessels
  • Regulates mood and memory
  • Affects the body’s sleep cycles

Norepinephrine has an important role in moderating memory, mood, alertness, and attention. Low levels of norepinephrine are associated with certain symptoms of depression and anxiety. 

What Do SNRIs Treat?

SNRIs are primarily used to treat depression and anxiety disorders. However, there are off-label applications as well.  


SNRIs are primarily prescribed as a depression treatment due to their effects on serotonin and norepinephrine. While serotonin contributes to general feelings of well-being, norepinephrine increases energy levels, arousal, and alertness. 


SNRIs also treat anxiety disorders; however, they don’t work for everybody. While increased serotonin levels can help improve anxiety symptoms, increased norepinephrine levels can have the opposite effect and actually make someone feel even more nervous. 

This is because of norepinephrine’s ability to heighten alertness and blood pressure, which may negatively impact some people with anxiety.

Off-Label Treatment for ADHD

Certain SNRIs are used as an off-label treatment for managing ADHD symptoms. While CNS stimulants are the first-line treatment for managing symptoms of ADHD, SNRIs can also be effective due to their impact on norepinephrine, which regulates attention, focus, and memory. 

What Are the Most Commonly Prescribed SNRIs?

SNRIs have been on the market since the mid-1990s. Currently, there are seven SNRI brands available in the US:

  • Effexor (venlafaxine)
  • Cymbalta (duloxetine)
  • Irenka (duloxetine)
  • Pristiq (desvenlafaxine)
  • Khedezla (desvenlafaxine) 
  • Fetzima (Levomilnacipran)
  • Savella (milnacipran)


The cost of SNRIs is less consistent than SSRIs, but they are mostly inexpensive. 30 capsules of venlafaxine (generic Effexor), for example, can cost as little as $29, but other medications can be much more expensive. 

The lowest price of Fetzima, which is not available in generic form, is about $539 for 30 capsules, making it dramatically more expensive than any other available antidepressant.

Typically, most insurance plans cover generic medications. Check with your carrier to discuss your coverage. If a medication is not covered, your healthcare provider or the manufacturer may be able to provide coupons to help cut the cost.

Common SNRI Side Effects

SNRIs are considered safe, but they do have some (often temporary) side effects, including:

  • Increased blood pressure
  • Increased heart rate
  • Headache
  • Difficulty urinating
  • Nausea
  • Eating too much or too little
  • Dry mouth
  • Excessive sweating
  • Constipation
  • Muscle weakness
  • Tremors
  • Irritability
  • Heart palpitations
  • Dizziness
  • Insomnia
  • Drowsiness
  • Fluid retention, especially in older adults
  • Inability to maintain an erection or have an orgasm (in men)

In rare cases, SNRIs may cause serious side effects, such as bruising or muscle cramps. If you experience severe side effects, contact your healthcare provider right away.

SNRI Warnings for Use

Though SNRIs are considered safe, certain people should avoid taking them. 

People who are pregnant or breastfeeding should not use SNRIs unless it’s deemed medically necessary. If taking SNRIs for the second half of pregnancy, the baby might develop SNRI withdrawal symptoms, which include tremors, feeding issues, and breathing difficulties.

People who have liver problems should consult with a doctor before starting treatment on SNRIs. SNRIs are metabolized by the liver and will put extra strain on it.

Norepinephrine raises blood pressure in the body and might cause cardiovascular issues for people with hypertension. People who have hypertension should consult with a doctor before starting SNRIs. 

You should never stop taking any SNRI without guidance from your medical provider, as withdrawal symptoms may occur.

Serotonin Syndrome

A rare condition called serotonin syndrome can also occur with SNRIs. If you experience any of the following symptoms, immediately contact emergency health services:

  • Anxiety, agitation, confusion, or restlessness
  • Severe sweating
  • Tremors
  • Lack of coordination
  • Rapid heart rate

Black Box Warning

All antidepressants, SNRIs included, come with the same black box warning that SSRIs have.  Based on certain placebo-controlled studies, children and adolescents in the trial reported an increase in suicidal thoughts and ideation compared to the placebo group. 

These findings have not been replicated in adult populations, however, the FDA requires that these risks be disclosed.

Which Anxiety or Depression Medication Is Right For You?

Finding the right depression treatment takes trial and error. In general, SSRIs are the first-line treatment for depression and are also effective when treating anxiety symptoms. However, based on your individual needs, medical history, and toleration of the side effects, SSRIs might not be the best treatment option for you.

SNRIs help elevate norepinephrine levels in addition to serotonin and dopamine levels. Norepinephrine has different effects on the body, which makes SNRIs an alternative for people who didn’t respond well to SSRIs. 

People with ADHD and comorbid depression might benefit from SNRIs because of norepinephrine’s role in moderating alertness, attention, concentration, and mood.

Ultimately, finding the right treatment requires a bit of patience and a willingness to try different medications. It can be challenging, but you never have to go through the process alone. 

If You Suffer from Anxiety or Depression, Klarity Can Help

Klarity has helped 30,000+ Americans find online depression, anxiety, ADHD, and insomnia treatment through our easy, affordable, and fast telemedicine services. We connect you with a mental health specialist who can diagnose illness and prescribe medication over through a video telehealth visit.

Why choose Klarity? 

  • Appointments with your medical provider are available within 48 hours
  • You can meet with them anywhere you have internet.
  • You no longer have to wait weeks for an appointment.
  • Pick up your prescription at your local pharmacy.
  • Insurance is not required, and affordable care is offered to everyone. 

Klarity makes modern mental health care easy. Discover how we can help you


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Debra Fulghum Bruce, PhD. “What Is Depression?” WebMD.

“Dopamine.” Cleveland Clinic.

Giovanni B. Cassano, MD; Nicolò Baldini Rossi, MD; Stefano Pini, MD. “Psychopharmacology of anxiety disorders.” Dialogues Clin Neurosci. 2002 Sep; 4(3): 271–285.

“Norepinephrine (Noradrenaline).” Cleveland Clinic.

Jennifer Fink. “Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs).” Healthline.

Mayo Clinic Staff. “Anxiety Disorders.” Mayo Clinic.

Mayo Clinic Staff. “Depression (major depressive disorder).” Mayo Clinic.

“Side effects – Selective serotonin reuptake inhibitors (SSRIs).” NHS.

“Serotonin.” Cleaveland Clinic.

Zawn Villines. “What are the differences between SSRIs and SNRIs?” Medical News Today.

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