Table of ContentsView AllTable of ContentsWhat They AreDifferencesUsesDosageSide EffectsWarnings
Table of ContentsView All
View All
Table of Contents
What They Are
Differences
Uses
Dosage
Side Effects
Warnings
Selective serotonin reuptake inhibitors (SSRIs) andserotonin-norepinephrine reuptake inhibitors(SNRIs) are two of the most common types of medications used to treat conditions such as depression, anxiety disorders, and obsessive-compulsive disorder. Both are known as reuptake inhibitors.
This article will explain how the medications work, when they’re prescribed, their side effects, and their differences.
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What Are SSRIs and SNRIs?
Neurotransmitters play a role in our moods, memory, focus, social interaction, sexual function, and other important aspects of human life. An imbalance or dysfunction of certain neurotransmitters is believed to affect mental health and is associated with several conditions, such asdepressionandanxiety.
Different neurotransmitters affect different functions of the brain. The main neurotransmitters associated with mental health include:
SSRIs and SNRIs, the two main reuptake inhibitors, are similar in many ways, but the the medications do have distinct differences.
What Are Selective Serotonin Reuptake Inhibitors (SSRIs)?
Difference Between SSRIs and SNRIs
SSRI medications include:
SNRI medications include:
Neither SSRIs nor SNRIs are inherently better than the other. Which medication works best varies based on the individual and the condition it is used for.
Similarities and Differences Between Zoloft and Prozac
Uses of SSRIs vs. SNRIs
SSRIs and SNRIs are used to treat various mental health conditions. They are sometimes also used to treat other types of medical problems such as pain disorders or gastrointestinal conditions. Your healthcare provider may start you on one type of medication and switch to another one or alter the dose depending on how well it works for you and any side effects you experience.
SSRI Uses
SSRIs are most commonly used in treating:
They may also be used to treat other conditions such as:
SNRI Uses
The SNRI used depends on the condition being treated. The following medications are often prescribed for particular disorders:
Cymbalta (duloxetine)
Effexor (Venlafaxine)
Fetzima (levomilnacipran)
Pristiq (desvenlafaxine)
Savella (milnacipran)
Do SSRIs and SNRIs help with anxiety?Both SSRIs and some SNRIs help with anxiety. SSRIs are often prescribed as the first option, but both types of medications are effective for treating anxiety. The one that works best depends largely on the individual.
Do SSRIs and SNRIs help with anxiety?
Both SSRIs and some SNRIs help with anxiety. SSRIs are often prescribed as the first option, but both types of medications are effective for treating anxiety. The one that works best depends largely on the individual.
Before Prescribing
Before prescribing an SSRI or an SNRI, your healthcare provider will consider and discuss several factors with you, including:
Your healthcare provider may order blood tests or other tests to check for other medical considerations that could influence which medication is most appropriate.
It can take from two weeks to two months for the benefits of the medication to take full effect. Your healthcare provider will likely schedule a follow-up within a few weeks to check in on how the treatment is going and if there are side effects. They may advise continuing with the same medication and dosage, changing the dosage, or switching to a different medication altogether.
Be Mindful of Possible InteractionsAlways inform your healthcare provider and pharmacist about any medications (prescriptions, over-the-counter, and herbal), supplements, and vitamins that you currently take.Potential interactions are not always obvious and have the potential to cause side effects, influence the effectiveness of the medications, or even be dangerous.
Be Mindful of Possible Interactions
Always inform your healthcare provider and pharmacist about any medications (prescriptions, over-the-counter, and herbal), supplements, and vitamins that you currently take.Potential interactions are not always obvious and have the potential to cause side effects, influence the effectiveness of the medications, or even be dangerous.
Always inform your healthcare provider and pharmacist about any medications (prescriptions, over-the-counter, and herbal), supplements, and vitamins that you currently take.
Potential interactions are not always obvious and have the potential to cause side effects, influence the effectiveness of the medications, or even be dangerous.
Dosage of SSRIs vs. SNRIs
Dosages for SSRIs and SNRIs vary depending on the medication, the condition being treated, and the person taking it.
Always check with your healthcare provider about proper dosing, and never change doses without first discussing it with your healthcare provider.
SSRI Dosages
Serotonin SyndromeToo much serotonin can cause a condition calledserotonin syndrome. This condition can range from mild to life-threatening. It usually occurs when different medications that affect serotonin are taken together, but it can happen if SSRIs or SNRIs are taken at too high a dosage.Consult your healthcare provider if you experience the following symptoms:Nausea or vomitingDiarrheaConfusionMuscle rigidityDilated pupilsShiversVery high temperatureSeizuresIrregular heartbeatIf serotonin syndrome is suspected, seek medical attention immediately.
Serotonin Syndrome
Too much serotonin can cause a condition calledserotonin syndrome. This condition can range from mild to life-threatening. It usually occurs when different medications that affect serotonin are taken together, but it can happen if SSRIs or SNRIs are taken at too high a dosage.Consult your healthcare provider if you experience the following symptoms:Nausea or vomitingDiarrheaConfusionMuscle rigidityDilated pupilsShiversVery high temperatureSeizuresIrregular heartbeatIf serotonin syndrome is suspected, seek medical attention immediately.
Too much serotonin can cause a condition calledserotonin syndrome. This condition can range from mild to life-threatening. It usually occurs when different medications that affect serotonin are taken together, but it can happen if SSRIs or SNRIs are taken at too high a dosage.
Consult your healthcare provider if you experience the following symptoms:
If serotonin syndrome is suspected, seek medical attention immediately.
SNRI Dosages
ModificationsEach medication has guidelines for ways in which it may or may not be modified. Consult your pharmacist or medication package insert for more specific details.
Modifications
Each medication has guidelines for ways in which it may or may not be modified. Consult your pharmacist or medication package insert for more specific details.
How to Take and Store
It is important to take reuptake inhibitors as prescribed and avoid missing a dose. If you miss a dose, try to take it as soon as you remember, unless it’s almost time to take your next dose, in which case you should skip the missed dose. You should not take a double dose to “make up” for the one you missed.
Taking reuptake inhibitors with food may help preventnausea.
Unless otherwise specified, these medications should be:
Keep medication out of reach and sight of children.
How Long Do Antidepressants Take to Work?
Cymbalta RecallStarting in October 2024, over 200,000 bottles of duloxetine delayed-release capsules were recalled over concerns about the presence of nitrosamines, which can increase the risk of cancer.If you take duloxetine, check your medication packaging to see if it was part of the affected lots or call your pharmacist to find out. You should also contact your prescriber, as abruptly stopping a medication like duloxetinecan be dangerous.The recalled lots have expiration dates from November 2024 to December 2025. You can check the lot numbers in the FDA enforcement reports released inOctoberandDecember.
Cymbalta Recall
Starting in October 2024, over 200,000 bottles of duloxetine delayed-release capsules were recalled over concerns about the presence of nitrosamines, which can increase the risk of cancer.If you take duloxetine, check your medication packaging to see if it was part of the affected lots or call your pharmacist to find out. You should also contact your prescriber, as abruptly stopping a medication like duloxetinecan be dangerous.The recalled lots have expiration dates from November 2024 to December 2025. You can check the lot numbers in the FDA enforcement reports released inOctoberandDecember.
Starting in October 2024, over 200,000 bottles of duloxetine delayed-release capsules were recalled over concerns about the presence of nitrosamines, which can increase the risk of cancer.If you take duloxetine, check your medication packaging to see if it was part of the affected lots or call your pharmacist to find out. You should also contact your prescriber, as abruptly stopping a medication like duloxetinecan be dangerous.
The recalled lots have expiration dates from November 2024 to December 2025. You can check the lot numbers in the FDA enforcement reports released inOctoberandDecember.
Side Effects of SSRIs vs. SNRIs
The side effects of SSRIs and SNRIs typically happen at the beginning of treatment and often lessen over time. Your healthcare provider will prescribe a medication with these side effects in mind.
The common side effects of SSRIs and SNRIs include:
SSRIs
SNRIs
If the side effects are concerning or intolerable, talk with your healthcare provider to see if adjustments can be made.
Which antidepressant has the fewest side effects?
The best thing you can do is work with your healthcare provider to find the best balance between effectiveness and side effects.
Warnings and Interactions
Some things should be avoided or approached with caution when taking SSRIs or SNRIs, including:
SSRIs should be used with caution as a treatment forbipolar disorderas they may exacerbate rapid mood cycling.
Suicidality
In 2004, the FDA issued aboxed warningon SSRIs regarding their use in children and teens. A warning is still included in the package inserts for all antidepressants in common use, discussing the risk of suicidal thoughts, hostility, and agitation in children, teens, and young adults.
Anyone on antidepressants, particularly those under age 25, should be mindful of the potential for suicidal thoughts and actions, and seek help immediately if they notice signs or experience such thoughts.
Help Is AvailableIf you or someone you know are having suicidal thoughts, dial988to contact the988 Suicide & Crisis Lifelineand connect with a trained counselor. If you or a loved one is in immediate danger, call911.
Help Is Available
If you or someone you know are having suicidal thoughts, dial988to contact the988 Suicide & Crisis Lifelineand connect with a trained counselor. If you or a loved one is in immediate danger, call911.
Stopping Reuptake Inhibitors
You should not stop taking your medication abruptly or miss several doses. Doing so can cause unpleasant side effects.
It is important to discuss any changes, including stopping medication use, with your healthcare provider. If you want to stop taking your medication or change to a different one, always do so under the guidance of a healthcare provider who can help you wean off them safely.
Summary
SSRIs and SNRIs are medications that increase the levels of certain neurotransmitters in your brain. They are often prescribed to treat depression and other mental health conditions.
SSRIs block the absorption of serotonin, while SNRIs block the absorption of serotonin and norepinephrine. SSRIs are usually prescribed first since they tend to have fewer side effects.
Talk to your healthcare provider about any side effects you might experience while taking these medications, and always follow your healthcare provider’s instructions for dosage. Don’t stop taking any of these medications without talking to your healthcare provider.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Liu Y, Zhao J, Guo W.Emotional roles of mono-aminergic neurotransmitters in major depressive disorder and anxiety disorders.Front Psychol. 2018;9:2201. doi:10.3389/fpsyg.2018.02201Pompili M, Serafini G, Innamorati M, et al.Antidepressants and suicide risk: a comprehensive overview.Pharmaceuticals. 2010;3(9):2861-2883. doi:10.3390/ph3092861Speranza L, di Porzio U, Viggiano D, de Donato A, Volpicelli F.Dopamine: The neuromodulator of long-term synaptic plasticity, reward and movement control.Cells. 2021;10(4):735. doi:10.3390/cells10040735Unsworth N, Robison MK.A locus coeruleus-norepinephrine account of individual differences in working memory capacity and attention control.Psychon Bull Rev. 2017;24(4):1282-1311. doi:10.3758/s13423-016-1220-5National Health Service.Overview - SSRI antidepressants.Locher C, Koechlin H, Zion SR, et al.Efficacy and safety of selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and placebo for common psychiatric disorders among children and adolescents: a systematic review and meta-analysis.JAMA Psychiatry. 2017;74(10):1011. doi:10.1001/jamapsychiatry.2017.2432Sansone RA, Sansone LA.Serotonin norepinephrine reuptake inhibitors: a pharmacological comparison.Innov Clin Neurosci. 2014;11(3-4):37-42.American Academy of Family Physicians.How to safely take antidepressants.National Health Service.Dosage - selective serotonin reuptake inhibitors (SSRIs).Food and Drug Administration.What to Know and Do About Possible Nitrosamines in Your Medication.Wang SM, Han C, Bahk WM, et al.Addressing the side effects of contemporary antidepressant drugs: A comprehensive review.Chonnam Med J. 2018;54(2):101-112. doi:10.4068/cmj.2018.54.2.101National Health Service.Cautions - selective serotonin reuptake inhibitors (SSRIs).McGirr A, Vöhringer PA, Ghaemi SN, Lam RW, Yatham LN.Safety and efficacy of adjunctive second-generation antidepressant therapy with a mood stabiliser or an atypical antipsychotic in acute bipolar depression: a systematic review and meta-analysis of randomised placebo-controlled trials.The Lancet Psychiatry. 2016;3(12):1138-1146. doi:10.1016/S2215-0366(16)30264-4
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Liu Y, Zhao J, Guo W.Emotional roles of mono-aminergic neurotransmitters in major depressive disorder and anxiety disorders.Front Psychol. 2018;9:2201. doi:10.3389/fpsyg.2018.02201Pompili M, Serafini G, Innamorati M, et al.Antidepressants and suicide risk: a comprehensive overview.Pharmaceuticals. 2010;3(9):2861-2883. doi:10.3390/ph3092861Speranza L, di Porzio U, Viggiano D, de Donato A, Volpicelli F.Dopamine: The neuromodulator of long-term synaptic plasticity, reward and movement control.Cells. 2021;10(4):735. doi:10.3390/cells10040735Unsworth N, Robison MK.A locus coeruleus-norepinephrine account of individual differences in working memory capacity and attention control.Psychon Bull Rev. 2017;24(4):1282-1311. doi:10.3758/s13423-016-1220-5National Health Service.Overview - SSRI antidepressants.Locher C, Koechlin H, Zion SR, et al.Efficacy and safety of selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and placebo for common psychiatric disorders among children and adolescents: a systematic review and meta-analysis.JAMA Psychiatry. 2017;74(10):1011. doi:10.1001/jamapsychiatry.2017.2432Sansone RA, Sansone LA.Serotonin norepinephrine reuptake inhibitors: a pharmacological comparison.Innov Clin Neurosci. 2014;11(3-4):37-42.American Academy of Family Physicians.How to safely take antidepressants.National Health Service.Dosage - selective serotonin reuptake inhibitors (SSRIs).Food and Drug Administration.What to Know and Do About Possible Nitrosamines in Your Medication.Wang SM, Han C, Bahk WM, et al.Addressing the side effects of contemporary antidepressant drugs: A comprehensive review.Chonnam Med J. 2018;54(2):101-112. doi:10.4068/cmj.2018.54.2.101National Health Service.Cautions - selective serotonin reuptake inhibitors (SSRIs).McGirr A, Vöhringer PA, Ghaemi SN, Lam RW, Yatham LN.Safety and efficacy of adjunctive second-generation antidepressant therapy with a mood stabiliser or an atypical antipsychotic in acute bipolar depression: a systematic review and meta-analysis of randomised placebo-controlled trials.The Lancet Psychiatry. 2016;3(12):1138-1146. doi:10.1016/S2215-0366(16)30264-4
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Liu Y, Zhao J, Guo W.Emotional roles of mono-aminergic neurotransmitters in major depressive disorder and anxiety disorders.Front Psychol. 2018;9:2201. doi:10.3389/fpsyg.2018.02201Pompili M, Serafini G, Innamorati M, et al.Antidepressants and suicide risk: a comprehensive overview.Pharmaceuticals. 2010;3(9):2861-2883. doi:10.3390/ph3092861Speranza L, di Porzio U, Viggiano D, de Donato A, Volpicelli F.Dopamine: The neuromodulator of long-term synaptic plasticity, reward and movement control.Cells. 2021;10(4):735. doi:10.3390/cells10040735Unsworth N, Robison MK.A locus coeruleus-norepinephrine account of individual differences in working memory capacity and attention control.Psychon Bull Rev. 2017;24(4):1282-1311. doi:10.3758/s13423-016-1220-5National Health Service.Overview - SSRI antidepressants.Locher C, Koechlin H, Zion SR, et al.Efficacy and safety of selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and placebo for common psychiatric disorders among children and adolescents: a systematic review and meta-analysis.JAMA Psychiatry. 2017;74(10):1011. doi:10.1001/jamapsychiatry.2017.2432Sansone RA, Sansone LA.Serotonin norepinephrine reuptake inhibitors: a pharmacological comparison.Innov Clin Neurosci. 2014;11(3-4):37-42.American Academy of Family Physicians.How to safely take antidepressants.National Health Service.Dosage - selective serotonin reuptake inhibitors (SSRIs).Food and Drug Administration.What to Know and Do About Possible Nitrosamines in Your Medication.Wang SM, Han C, Bahk WM, et al.Addressing the side effects of contemporary antidepressant drugs: A comprehensive review.Chonnam Med J. 2018;54(2):101-112. doi:10.4068/cmj.2018.54.2.101National Health Service.Cautions - selective serotonin reuptake inhibitors (SSRIs).McGirr A, Vöhringer PA, Ghaemi SN, Lam RW, Yatham LN.Safety and efficacy of adjunctive second-generation antidepressant therapy with a mood stabiliser or an atypical antipsychotic in acute bipolar depression: a systematic review and meta-analysis of randomised placebo-controlled trials.The Lancet Psychiatry. 2016;3(12):1138-1146. doi:10.1016/S2215-0366(16)30264-4
Liu Y, Zhao J, Guo W.Emotional roles of mono-aminergic neurotransmitters in major depressive disorder and anxiety disorders.Front Psychol. 2018;9:2201. doi:10.3389/fpsyg.2018.02201
Pompili M, Serafini G, Innamorati M, et al.Antidepressants and suicide risk: a comprehensive overview.Pharmaceuticals. 2010;3(9):2861-2883. doi:10.3390/ph3092861
Speranza L, di Porzio U, Viggiano D, de Donato A, Volpicelli F.Dopamine: The neuromodulator of long-term synaptic plasticity, reward and movement control.Cells. 2021;10(4):735. doi:10.3390/cells10040735
Unsworth N, Robison MK.A locus coeruleus-norepinephrine account of individual differences in working memory capacity and attention control.Psychon Bull Rev. 2017;24(4):1282-1311. doi:10.3758/s13423-016-1220-5
National Health Service.Overview - SSRI antidepressants.
Locher C, Koechlin H, Zion SR, et al.Efficacy and safety of selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and placebo for common psychiatric disorders among children and adolescents: a systematic review and meta-analysis.JAMA Psychiatry. 2017;74(10):1011. doi:10.1001/jamapsychiatry.2017.2432
Sansone RA, Sansone LA.Serotonin norepinephrine reuptake inhibitors: a pharmacological comparison.Innov Clin Neurosci. 2014;11(3-4):37-42.
American Academy of Family Physicians.How to safely take antidepressants.
National Health Service.Dosage - selective serotonin reuptake inhibitors (SSRIs).
Food and Drug Administration.What to Know and Do About Possible Nitrosamines in Your Medication.
Wang SM, Han C, Bahk WM, et al.Addressing the side effects of contemporary antidepressant drugs: A comprehensive review.Chonnam Med J. 2018;54(2):101-112. doi:10.4068/cmj.2018.54.2.101
National Health Service.Cautions - selective serotonin reuptake inhibitors (SSRIs).
McGirr A, Vöhringer PA, Ghaemi SN, Lam RW, Yatham LN.Safety and efficacy of adjunctive second-generation antidepressant therapy with a mood stabiliser or an atypical antipsychotic in acute bipolar depression: a systematic review and meta-analysis of randomised placebo-controlled trials.The Lancet Psychiatry. 2016;3(12):1138-1146. doi:10.1016/S2215-0366(16)30264-4
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