Mental Health
What Is The Difference Between SSRIs And SNRIs?

What Is The Difference Between SSRIs And SNRIs?

6 min read


Caitlin Harper

For people struggling with depression, antidepressants can sometimes be prescribed to help manage their symptoms. Not all depression requires treatment with medication, but if you and your doctor decide that medication might be a good option for you, SSRIs, SNRIs, or a combination could be used.

SSRIs, or selective serotonin reuptake inhibitors, and SNRIs, or serotonin and norepinephrine reuptake inhibitors, are two different types of antidepressants. SSRIs increase serotonin levels in the brain, while SNRIs increase both serotonin and norepinephrine levels.

It can be hard to understand how different antidepressants work and which is the best fit for you. While your best resource is your doctor, it never hurts to do some homework beforehand so you have a better idea of what might be available to you so you can make the best decision for your care.

How do SNRIs and SSRIs work?

Selective serotonin reuptake inhibitors such as SSRIs, SNRIs, NRIs, NDRIs, and SNDRIs are all reuptake inhibitors, meaning they block the reuptake or reabsorption of your neurotransmitters, the body’s chemical messengers. They are the molecules used by the nervous system to transmit messages between neurons, or from neurons to muscles. Neurotransmitters are involved in countless functions of the nervous system. They work to keep our brains functioning, they control bodily functions like breathing, and control psychological functions like joy and fear.

If your levels of neurotransmitters are already low, reuptake can reduce the amount of neurotransmitters in the brain. By blocking the reuptake of neurotransmitters and keeping the levels of neurotransmitters high, reuptake inhibitors increase the amount of neurotransmitters circulating or working at one time, which can have a positive effect on your mood.

There are three neurotransmitters that antidepressants can target in order to help regulate your mood: dopamine, norepinephrine, and serotonin. Each one works a bit differently.

SSRI vs. SNRI: What is the difference?

While the aim of reuptake inhibitors is essentially the same, SSRIs and SNRIs have slightly different ways of achieving a similar end.

An SSRI is any of a class of antidepressants that are thought to act by blocking the reuptake of serotonin into serotonin-containing presynaptic neurons in the central nervous system.

Examples of SSRIs (with their brand names in parenthesis):

  • Citalopram (Celexa)
  • Escitalopram (Lexapro)
  • Fluoxetine (Prozac, Sarafem, Symbyax)
  • Fluvoxamine (Luvox, Luvox CR)
  • Paroxetine (Paxil, Paxil CR, Pexeva)
  • Sertraline (Zoloft)
  • Vilazodone (Viibryd)

An SNRI is any of a class of antidepressants that exert their therapeutic effects by interfering with the reabsorption of both serotonin and norepinephrine by the neurons that released them.

Examples of SNRIs (with their brand names in parenthesis):

  • Duloxetine (Cymbalta)
  • Venlafaxine (Effexor, Effexor XR)
  • Levomilnacipran (Fetzima)
  • Desvenlafaxine (Pristiq, Khedezla)

In addition to depression, SSRIs could be prescribed to treat conditions like generalized anxiety disorder, obsessive compulsive disorder, panic disorder, severe phobias such as agoraphobia and social phobia, bulimia, and post-traumatic stress disorder. Sometimes they’re also used to treat conditions such as premature ejaculation, premenstrual syndrome, fibromyalgia, irritable bowel syndrome, and pain. SNRIs are also sometimes used to treat other conditions, such as anxiety disorders and long-term (chronic) pain, especially nerve pain.

SSRI vs. SNRI: Which one is better?

The short answer is: whatever you and your doctor decide is best for your specific situation!

Sometimes doctors prescribe a combination of SSRIs and SNRIs for their patients’ treatment and norepinephrine and dopamine reuptake inhibitors, or NDRIs, can be used as well. While SSRIs are more commonly prescribed because they can be more effective at mood regulation, sometimes with fewer side effects, SNRIs have the ability to improve energy levels, so they each have their own benefits. While a boost of energy might sound better, treating depression is about balancing the chemicals in your brain, so your doctor can determine what the best treatment choice and dosage is for you at a particular time.

Studies show that the benefit generally depends on the severity of the depression: The more severe the depression, the greater the benefits will be. In other words, antidepressants are effective against chronic, moderate and severe depression while they can be less effective in mild depression.

One of the largest issues with both SSRIs and SNRI medications is that even if they help at first, any antidepressant may lose its effect after months or years, sometimes because the brain has become less responsive to the drug (tolerance). Solutions include increasing the dose and switching to another antidepressant with a different mechanism of action.

Common side effects of antidepressants may include:

  • Nausea and vomiting
  • Diarrhea
  • Weight gain
  • Headache
  • Drowsiness
  • Dizziness
  • Insomnia or sleep disturbances
  • Nausea
  • Diarrhea or constipation
  • Sexual problems
  • Suicidal thoughts

It’s important to discuss any side effects with your doctor in case they want to adjust your dosage or medication.

How long will I be on antidepressants?

Antidepressants are usually taken daily. In the first few weeks and months, the goal is to relieve the symptoms and, when possible, even make the depression go away. It usually takes some time for your doctor to figure out the medication or combination that works best for you. It’s hard, but be patient! Many antidepressants take a few weeks for you to notice any improvement in your symptoms.

After that, the treatment is continued for at least four to nine months with the goal of preventing the symptoms from coming back. Sometimes, medication is continued for longer to prevent relapses. In order to discontinue use, most people need to gradually decrease their dose over time, as stopping immediately could cause withdrawal-like symptoms like dizziness, headaches, flu-like symptoms, and lethargy.

Some people take antidepressants for years. The duration of treatment varies from person to person and depends on the severity of your depression, how your symptoms develop over time, and whether the depression returns or subsides.

Pairing your medication with therapy can be more effective than treating depression with medication alone

SSRIs and SNRIs are both prescription medications, so you must talk to a doctor to begin taking them. While antidepressants can treat the symptoms of depression or other conditions, they can’t necessarily deal with everything. They’ll often be prescribed alongside therapy to help deal with the roots or causes of your symptoms.

For depression, two kinds of psychotherapy called cognitive-behavioral therapy and interpersonal psychotherapy, as well as antidepressant medications, have been shown to be helpful. There is some evidence that combining psychotherapy and medications may be more effective than either treatment alone.

There are many treatment options available for depression, anxiety, and other mood disorders. Working with your doctor and therapist will help figure out the best treatment for you to get the care and support you deserve.

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About the author

Caitlin is an organizational change strategist, advisor, writer, and the founder of Commcoterie, a change management communication consultancy. She helps leaders and the consultants who work with them communicate change for long-lasting impact. Caitlin is a frequent speaker, workshop facilitator, panelist, and podcast guest on topics such as organizational change, internal communication strategy, DEIBA, leadership and learning, management and coaching, women in the workplace, mental health and wellness at work, and company culture. Find out more, including how to work with her, at

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