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SSRI vs SNRI: Differences, Side Effects, Benefits and Uses

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Anxiety disorders are a very common type of mental illness that affects around 40 million American adults. These disorders, including generalized anxiety disorder, panic disorder, and social phobia, often co-occur with depression. Both anxiety and depression can be effectively treated with psychotherapy, medications, or a combination of the two. Yet, many people do not get the treatment they need due to healthcare costs and the stigma that comes with mental illness. 

Different types of medications are used in treating mental health conditions like anxiety and depression. Two of the most common ones are SSRIs (selective serotonin reuptake inhibitors) and SNRIs (serotonin and norepinephrine reuptake inhibitors). Both are prescription medications that are indicated to treat major depressive disorders and generalized anxiety disorders. 

If you and your doctor decide that antidepressants are a good treatment option for you, it can be challenging to figure out which one is the better fit for youSSRIs vs. SNRIs? The best person to help you decide is your doctor, of course, but it doesn’t hurt to do your homework and gain a better understanding of these drug classes.

What are SSRIs?

Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed to treat major depressive disorder. They are a popular choice because they are generally safe in most people and cause fewer side effects versus other types of antidepressants. 

Examples of SSRIs include fluoxetine (Prozac), citalopram (Celexa), paroxetine (Paxil), sertraline (Zoloft), fluvoxamine (Luvox), and escitalopram (Lexapro).

How do SSRIs work?

Neurotransmitters are chemical messengers that transmit signals between neurons or brain cells. There are different types of neurotransmitters in the brain, including serotonin, norepinephrine, and dopamine. SSRIs work by regulating the level of serotonin in the brain. As the name suggests, selective serotonin reuptake inhibitors exert their actions by selectively blocking the reuptake of serotonin. Simply put, SSRIs increase serotonin levels in the brain.

What are SNRIs? How do they work?

Serotonin and norepinephrine reuptake inhibitors (SNRIs) are prescribed to regulate a person’s mood and relieve depression. They work by blocking the reuptake of both serotonin and norepinephrine. In other words, SNRIs increase both serotonin and norepinephrine levels in the brain vs SSRI just increases serotonin. 

Examples of SNRIs include venlafaxine (Effexor XR), duloxetine (Cymbalta), desvenlafaxine (Pristiq), and levomilnacipran (Fetzima).

Is an SNRI better than an SSRI for anxiety and depression?

As noted above, SSRIs and SNRIs are drugs that are frequently used to treat depression and anxiety, including panic disorder, social phobia, and others. 

While both SNRIs and SSRIs are safe and effective, SSRIs are prescribed more often because they have greater efficacy in regulating mood and are typically better tolerated with fewer side effects. 

However, SNRI medications have some distinct advantages over selective serotonin reuptake inhibitors (SSRIs). SNRIs may be recommended if you have chronic pain, low energy levels, sleep difficulties, poor concentration, or inability to focus. However, SNRIs can cause side effects such as panic attacks and high blood pressure. Therefore, they may not be suitable for people with a history of heart problems or panic disorders.

Ultimately, the choice between SSRIs and SNRIs depends on symptoms and other factors such as health history and medication profile. Your doctor will help you decide the best treatment options and specific medication for your mental health condition.

Side effects of SSRIs vs. SNRIs

Both classes of antidepressants, selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), produce similar side effects. However, SSRIs are more commonly prescribed for treating depression because they are less likely to cause severe side effects. 

Common side effects of both types of drugs include dizziness, drowsiness, headaches, blurred vision, dry mouth, constipation, insomnia, nausea, and reduced sexual desire. At the beginning of therapy, some people experience suicidal ideation and desire to self-harm; this risk increases in children and young people under 25, thus, use with caution; supervision is essential for children who are initiated on any type of antidepressant.

One of the more serious side effects of an SSRI or SNRI is called serotonin syndrome. The risk of this syndrome t becomes significant with high doses or when these drugs interact with other medications or herbal supplements. Symptoms include confusion, agitation, rapid heart rate, and sweating. If you are on an antidepressant drug, including MAOIs, and experience any such symptoms, you should obtain medical attention as soon as possible.

Are antidepressants addictive?

No, SSRIs and SNRIs are not addictive, but they can cause withdrawal symptoms if stopped abruptly. That’s why it is important to always speak to your doctor before discontinuing these medications.

Which is best for anxiety: SSRI vs SNRI?

It’s important to keep in mind that different people can respond differently to the same medication. Therefore, what works well for one person may not be the best treatment choice for someone else. 

Your doctor will help you decide on the best medication for your depression after reviewing your general and mental health history. They will take into consideration your symptoms, other medical problems, and what other medications you are taking. They will also take into account what has worked versus what has not worked for you previously if you’ve received treatment for depression and anxiety disorders before.

Do I really need antidepressants? What are the advantages of taking SSRIs or SNRIs?

When taken as directed, SSRIs and SNRIs can significantly improve your quality of life. Both categories of drugs are approved treatments for depression and anxiety. They work by increasing the levels of important brain chemicals called neurotransmitters. 

Like all medications, an SSRI or SNRI can cause side effects. However, in general, they are well tolerated. Therefore, the risk of side effects associated with these medicines is low compared to the benefit they can provide. And in many patients, the side effects of SSRIs and SNRIs go away over time with continued treatment.

It may take a little time and experimentation to determine whether you need an SSRI or an SNRI and which specific medication works best for you. It is also worth remembering that an antidepressant medication takes several weeks to start working. If you don’t notice any improvement in your symptoms after a few days of treatment, please do not be disheartened since it typically takes 4 to 6 weeks for positive effects to be noticeable.


1. https://adaa.org/understanding-anxiety/facts-statistics

2. https://www.mayoclinic.org/diseases-conditions/depression/in-depth/ssris/art-20044825

3. https://www.mayoclinic.org/diseases-conditions/depression/in-depth/antidepressants/art-20044970