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SSRI vs. SNRI: Everything That You Need to Know

SSRI vs. SNRI: Everything That You Need to Know

When it comes to treating anxiety, depression, or other mood disorders and mental illnesses, your provider may recommend SSRI or SNRI medications. Alternatively, if you have already tried an SSRI medication and it didn’t work for you, your provider may recommend trying an SNRI instead.

SSRI and SNRI medications function in very similar ways, but they are not identical. Building a more complete understanding of these two types of medications can help you better comprehend the way they work inside your body, what makes them different, and whether or not they may be beneficial for you. 

What Are SSRIs?

SSRIs are recognized as the most commonly prescribed antidepressants, and they work by increasing the level of serotonin in your brain. Serotonin is one of many neurotransmitters in your body that work to carry signals between brain nerve cells, and serotonin helps regulate your mood. Thus, increasing your serotonin levels can help stabilize your moods and emotions. 

How Do SSRIs Work?

SSRI is short for selective serotonin reuptake inhibitors, and they work by preventing your body from reabsorbing serotonin into your neurons, therefore increasing the available levels of serotonin for your brain to use. 

Serotonin is a neurotransmitter that helps maintain mental balance, so increasing serotonin works to improve your mood and reduce symptoms of depression and anxiety.

Additionally, SSRIs change your brain by stimulating the growth of new cells and creating stronger connections, particularly in an area of the brain called the dorsolateral prefrontal cortex (DLPFC). New cell growth in the DLPFC can regulate areas of your brain that control anger, fear, memories, and mood.

Some of the most commonly prescribed SSRIs include:

  • Citalopram (Celexa)
  • Escitalopram (Lexapro)
  • Fluoxetine (Prozac)
  • Paroxetine (Paxil, Pexeva)
  • Sertraline (Zoloft)

Interestingly, if you try one SSRI and find that your body does not tolerate it well, you may still be able to tolerate a different SSRI. If you are experiencing unwanted side effects, your provider will work with you to adjust your medication or recommend another SSRI that may be a better fit for your needs. 

Experiences with depression may vary as individuals respond to medications in different ways. This is why matching you with the right medication for your individual needs is essential.

Possible side effects of SSRIs include:

  • Nausea, vomiting, or diarrhea
  • Headaches
  • Drowsiness
  • Dry mouth
  • Insomnia or other sleep disturbances
  • Restlessness
  • Dizziness
  • Reduced libido
  • Changes in appetite that may lead to weight loss or weight gain

Usually, side effects go away within a week or two after your body adjusts to the medication. If they don’t go away or you’re concerned about them, talk with your provider. We may simply need to adjust your dose.

What Are SNRIs?

Whereas SSRIs impact your levels of serotonin, SNRIs impact the levels of both serotonin and norepinephrine. Aside from treating depression, SNRIs are sometimes used to treat other conditions, including anxiety disorders and chronic pain, especially chronic nerve pain.

How Do SNRIs Work?

SNRI is short for serotonin-norepinephrine reuptake inhibitors, and just as SSRIs can increase the amount of serotonin in your brain, SNRIs help boost levels of serotonin and norepinephrine. While serotonin works on mental balance and creates feelings of well-being, norepinephrine promotes feelings of alertness and energy — this power duo can help relieve symptoms of depression and anxiety and boost your mood. 

Like SSRIs, there are several different SNRIs available, including:

  • Desvenlafaxine (Pristiq)
  • Duloxetine (Cymbalta), which has also been approved to treat anxiety and some types of chronic pain
  • Levomilnacipran (Fetzima)
  • Venlafaxine (Effexor XR), which has also been approved for treatment of certain anxiety disorders and panic disorder

Like SSRIs, all forms of SNRIs work in similar ways, and thus may produce similar side effects. WIth both SSRIs and SNRIs, some people may not experience side effects at all, or may experience only mild side effects. Most common side effects are often temporary, and you’ll work with your provider to minimize them.

That said, the most common potential side effects of SNRIs include:

  • Nausea
  • Dizziness
  • Headaches
  • Dry mouth
  • Excessive sweating 

Aside from these, there are also some less common side effects which may present themselves:

  • Tiredness
  • Constipation
  • Insomnia
  • Reduced libido or other changes in sexual function or desire, including erectile dysfunction
  • Loss of appetite

What is the Difference Between SSRIs and SNRIs?

SSRIs are selective serotonin reuptake inhibitors, meaning they only impact the amount of serotonin in your body. SNRIs are serotonin-norepinephrine reuptake inhibitors, meaning they impact both serotonin and norepinephrine rather than only serotonin. While SSRIs and SNRIs are very similar, they are not one and the same

This is also why SSRIs are called “selective” serotonin reuptake inhibitors — they are aimed only at increasing your serotonin levels rather than impacting other neurotransmitters too. SNRIs, however, are aimed at increasing both serotonin and norepinephrine.

Both SSRIs and SNRIs have the potential to induce some side effects, but these are typically mild and should go away within a few weeks. Anytime you experience side effects that become severe or do not go away, you should call your provider and tell them about your symptoms. Your provider will be able to give you a professional opinion about whether or not it may be best to switch your prescription or try a different treatment method. 

Both types of antidepressants also have the potential for drug and supplement interactions, too, which is why it is important to inform your provider ahead of time if you are taking any other medications, vitamins, or supplements. 

If you believe that medication may be the best treatment option for your depression or anxiety, Brightside is here to help you every step of the way, and you can even have your medication delivered right to your door in most states. 

Start by taking our free online assessment to help us accurately assess your needs and concerns, then match you with a psychiatric provider. Your provider will work with you to come up with a plan for you to start feeling like yourself again, whether it be therapy, medication, or a combination of the two. 

Depression and anxiety can be tough, but Brightside is here to help you right from the comfort of your own home.

The Bottom Line

SSRIs and SNRIs work in very similar ways, and the main difference is just that SNRIs impact two neurotransmitters rather than one to help restore mental balance and reduce symptoms of depression and anxiety. 

Both SSRIs and SNRIs have the potential to cause some mild side effects that may take a few weeks to go away, but if you start experiencing any severe side effects or symptoms that do not go away, you should consult your doctor for next steps. 

Like most medications, these antidepressants can also interact with other drugs, making it very important to inform your provider of any other medications, and even vitamins or supplements, that you are taking before you start taking SSRIs or SNRIs. 

If you are struggling with depression, anxiety, or other mental health challenges and you are looking for professional help, Brightside is here to support you every step of the way.

Get started today with our free online assessment for the first step toward getting back to feeling like you



Selective serotonin reuptake inhibitors (SSRIs) – Mayo Clinic

Serotonin and norepinephrine reuptake inhibitors (SNRIs) – Mayo Clinic

SNRI Medications For Anxiety: SNRI Vs SSRI –


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