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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 that might make one option more suitable for treating your particular symptoms. 

In this article, we’ll discuss both types of antidepressants so you can better understand the pros and cons of each treatment. 

If you have anxiety or depression and are interested in treating your symptoms with an SSRI or SNRI antidepressants, make an appointment with a medical professional on Klarity today. Klarity connects you with a licensed healthcare provider in your state for convenient and affordable online anxiety and depression treatment, including a comprehensive evaluation, diagnosis, and prescription medication if applicable.

Schedule your first private telehealth visit on Klarity today and be seen by an anxiety or depression specialist in as little as 48 hours. 

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.

SSRIsSNRIs
Drug ClassSelective serotonin reuptake inhibitors (SSRIs)Selective serotonin and norepinephrine reuptake inhibitors (SNRIs)
Brand/Generic StatusBrand-names and generics available

Most common SSRIs:
• Prozac (fluoxetine)
• Paxil (paroxetine)
• Zoloft (sertraline)
• Celexa (citalopram)
• Luvox (fluvoxamine)
• Lexapro (escitalopram)
• Trintellix (vortioxetine)
• Viibryd (vilazodone)
Brand names and generics available

Most common SNRIs:
• Effexor (venlafaxine)
• Cymbalta (duloxetine)
• Irenka (duloxetine)
• Pristiq (desvenlafaxine)
• Khedezla (desvenlafaxine)
• Fetzima (levomilnacipran)
• Savella (milnacipran)

Form(s) of the DrugCommon forms of SSRIs include:
• Color-coded* capsules
• Color-coded* tablets
• Flavored liquid suspensions

*Color-coding often indicates dosage amount
Common forms of SNRIs include:
• Color-coded* capsules
• Color-coded* tablets
• Flavored liquid suspensions

*Color-coding often indicates dosage amount
Standard DosageVaries, depending on SSRI and condition being treatedVaries, depending on SNRI and condition being treated
Conditions TreatedConditions most often treated:
• Major depressive disorder
• Generalized anxiety disorder

Other conditions treated:
• Obsessive-compulsive disorder (OCD)
• Eating disorders
• Premenstrual dysphoric disorder (PMDD)

Different SSRIs are • FDA-approved for different uses

Many SSRIs are prescribed off-label to treat certain conditions
Conditions most often treated:
• Depression
• Anxiety disorders

Other conditions treated:
• Attention deficit
hyperactivity disorder (ADHD)


Different SNRIs are FDA-approved for different uses

Many SNRIs are prescribed off-label to treat certain conditions
CostAverage cost of a 30-day supply:
• $4 to $40 for generic formulas*
• $130 or more for brand-name formulas**

*Some SSRIs don’t have a generic formula available for Rx.

**Cost of brand-name SSRIs may be offset by coupons and insurance
Average cost of a 30-day supply:
• $29 for generic formulas*
• $539 for brand-name formulas**

*Some SNRIs don’t have a generic formula available for Rx.

**Cost of brand-name SNRIs may be offset by coupons and insurance

Side-EffectsCommon side effects:
• Nausea, vomiting, GI upset, or diarrhea
• Dry mouth
• Headache
• Difficulty sleeping or insomnia
• Drowsiness or dizziness
• Increased nervousness, feelings of restlessness, or agitation
• Reduced libido, erectile dysfunction
• Increase or decrease appetite, leading to changes in weight
Common side effects:
• 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
Warnings For Use• Combination with other medications may cause serotonin syndrome
• Symptoms of serotonin syndrome include:
• Anxiety or agitation
• Fever, sweating
• Tremors
• Restlessness
• Confusion
• Lack of coordination
• Blood pressure and heart rate changes

• Rarely, SSRIs may cause
suicidal thoughts or behaviors
• Contact your doctor immediately if this occurs

• Discuss other medications with your doctor, as adverse reactions may occur
• Combination with other medications may cause serotonin syndrome
• Symptoms of serotonin syndrome include:
• Anxiety or agitation
• Fever, sweating
• Tremors
• Restlessness
• Confusion
• Lack of coordination
• Blood pressure and heart rate changes

• Contraindicated conditions include:
• Pregnancy
• Breastfeeding
• Liver problems
• Heart conditions

• Discuss other medications with your doctor, as adverse reactions may occur

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. Still, there are several differences that you need to understand before you can make an informed decision on which one is right for you. 

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 can communicate with one another more effectively. 

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 also be effective at treating other conditions, including anxiety, panic disorder, OCD, PTSD, and other mood disorders.

Depression

Depression (major depressive disorder or MDD) is a mood disorder that negatively affects how you think and feel, leading to emotions of sadness, apathy, and exhaustion. With MDD, these emotions severely impact your quality of life. If untreated, depression can lead to several 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 the 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 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 medications are prescribed more often than others due to their effectiveness or limited side effects. 

A licensed healthcare 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)

Costs

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 
  • 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 disorder can occur 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.

Suicidal Thoughts and Ideation

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

SNRIs effectively relieve 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.  

Depression

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

Anxiety

SNRIs can 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 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)

Costs

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 prescription 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:

  • High 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, people with certain health conditions should avoid 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, including tremors, feeding issues, and breathing difficulties.

People with liver problems should consult 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 a way that may 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.

SSRIs or SNRIs: Which Medication Is Right For You?

Finding the right depression treatment takes time. In general, SSRIs are the first-line treatment for depression and are also effective when treating anxiety symptoms. However, based on your needs, medical history, and toleration of the side effects, SSRIs might not be the best 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 don’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 medication for you requires the knowledge and assistance of a licensed medical professional specializing in depression and anxiety. If you need affordable, simple psychiatric treatment, Klarity can help.

Klarity has helped thousands of Americans find online depression and anxiety treatment through convenient, private, insurance-free telemedicine services. We’ll connect you with a board-certified mental health specialist who can diagnose your symptoms and prescribe the safest and most effective antidepressant for you if they determine it the best option for you.

To get started with Klarity, schedule an appointment. Within 48 hours, you can begin treatment and receive a prescription for an SSRI or SNRI that will be sent directly to your local pharmacy, if applicable. 

Sources

Dharminder Singh; Abdolreza Saadabadi. “Venlafaxine.” StatPearlshttps://www.ncbi.nlm.nih.gov/books/NBK535363/

Debra Fulghum Bruce, PhD. “What Is Depression?” WebMD. https://www.webmd.com/depression/guide/detecting-depression

“Dopamine.” Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22581-dopamine

Giovanni B. Cassano, MD; Nicolò Baldini Rossi, MD; Stefano Pini, MD. “Psychopharmacology of anxiety disorders.” Dialogues Clin Neurosci. 2002 Sep; 4(3): 271–285. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181684/

“Norepinephrine (Noradrenaline).” Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22610-norepinephrine-noradrenaline

Jennifer Fink. “Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs).” Healthline. https://www.healthline.com/health/depression/serotonin-norepinephrine-reuptake-inhibitors-snris

Mayo Clinic Staff. “Anxiety Disorders.” Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/anxiety/symptoms-causes/syc-20350961

Mayo Clinic Staff. “Depression (major depressive disorder).” Mayo Clinic. https://www.webmd.com/depression/guide/detecting-depression

“Side effects – Selective serotonin reuptake inhibitors (SSRIs).” NHS. https://www.nhs.uk/mental-health/talking-therapies-medicine-treatments/medicines-and-psychiatry/ssri-antidepressants/side-effects/

“Serotonin.” Cleaveland Clinic. https://my.clevelandclinic.org/health/articles/22572-serotonin

Zawn Villines. “What are the differences between SSRIs and SNRIs?” Medical News Today. https://www.medicalnewstoday.com/articles/ssri-vs-snri

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