Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

medication info

Serotonin and norepinephrine reuptake inhibitors (SNRIs) are commonly prescribed antidepressants. They are very similar to the older and more commonly used SSRIs. There is some evidence that SNRIs are more effective in treating severe depression [1]. They can also be used to treat chronic pain [2] and ADHD [3].

When it comes to anxiety and less severe depression: SNRIs are more helpful for some people, whereas SSRIs or other antidepressants are more helpful for other people. The only way to know for sure what works best for you is to try them.

Like other antidepressants, SNRIs work by restoring the balance of the chemicals in your brain (called neurotransmitters). SNRIs work by boosting two neurotransmitters:

  • Serotonin, which affects your mood, energy level, appetite, and sleep
  • Norepinephrine, which affects your energy level, focus and attention. Related to adrenaline and has similar effects

The difference between SNRIs and SSRIs is that SSRIs only affect serotonin.

How do I take an SNRI?

SNRIs must be taken every day. It usually takes several weeks before you feel the full effect. Taking a single pill won’t stop a panic attack, for example—but taking it daily may decrease your chances of having a panic attack in the future [4].

You might be tempted to stop taking them as soon as you feel better, thinking that you’ve been cured. Unfortunately, antidepressants are not a cure for depression—they are a way of managing it, not a way of making it go away forever. If you stop taking your antidepressant as soon as you feel better, you will likely go back to being depressed.

If you do decide to stop taking an antidepressant, it’s best to talk to your doctor first. Your doctor can help you reduce the dosage gradually, which will reduce withdrawal symptoms. (You can often do this by cutting your tablets in half for a few weeks, then into fourths for a few more weeks.) They may also help you find an alternative that has fewer side effects or is more effective.

Examples of SNRIs

Even though all SNRIs work in similar ways, they each have slightly different effects. So if one doesn’t work for you, another might. If you’ve tried multiple SNRIs and none of them work well—or they all give you side effects—it’s a good idea to ask your doctor about taking a different type of antidepressant.

Generic name

Brand name(s)

Desvenlafaxine

Pristiq

Duloxetine

Cymbalta

Levomilnacipran

Fetzima

Milnacipran

Savella

Venlafaxine

Effexor

Side effects of SNRIs

Common [5]:

  • Nausea
  • Dizziness
  • Headache, dry mouth, or sweating

Less Common [5][6]:

  • Sleeping more or less than usual
  • Weight gain
  • Low sex drive, or trouble achieving an erection or orgasm
  • Increased blood pressure

References

  1. Thase. (2008). Are SNRIs more effective than SSRIs? A review of the current state of the controversy. Psychopharmacology Bulletin 42(2), pp. 58-85. Retrieved from https://pubmed.ncbi.nlm.nih.gov/18668017/
  2. Stahl et al. (2005). SNRIs: The Pharmacology, Clinical Efficacy, and Tolerability in Comparison with Other Classes of Antidepressants. CNS Spectrums, 10(9), pp. 732-747. Retrieved from https://doi.org/10.1017/S1092852900019726
  3. Antshel et al. (2011). Advances in understanding and treating ADHD. BMC Medicine 9, p. 72. Retrieved from https://doi.org/10.1186/1741-7015-9-72
  4. SNRIs for panic attacks:
    Guilherme Graeff & Zangrossi. (2010). The Dual Role of Serotonin in Defense and the Mode of Action of Antidepressants on Generalized Anxiety and Panic Disorders. Central Nervous System Agents in Medicinal Chemistry 10(3) pp. 207-217. Retrieved from https://www.ingentaconnect.com/content/ben/cnsamc/2010/00000010/00000003/art00002
  5. Mayo Clinic Staff. (2019). “Serotonin and norepinephrine reuptake inhibitors (SNRIs).” Mayo Clinic, Mayo Foundation for Medical Education and Research. Retrieved from https://www.mayoclinic.org/diseases-conditions/depression/in-depth/antidepressants/art-20044970
  6. Sentarsieri & Schwartz. (2015). Antidepressant efficacy and side-effect burden: a quick guide for clinicians. Drugs in Context 4, pp. 212290. Retrieved from https://dx.doi.org/10.7573%2Fdic.212290

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