SSRI vs. SNRI: Differences, Side Effects, and How They Work
SSRIs and SNRIs are two common types of antidepressants used for depression and anxiety. They work in similar ways, but the main difference is that SSRIs mainly affect one chemical messenger in the brain, while SNRIs affect two.
The choice between them depends on your symptoms, other health conditions, other medicines, and how your body responds to treatment.
What are SSRIs and how do they work?
SSRI stands for selective serotonin reuptake inhibitor. Serotonin is a chemical messenger that nerve cells use to communicate. Serotonin signaling contributes to mood, sleep, digestion, and many other body functions.
SSRIs work in the brain by blocking part of the process that cells normally use to take serotonin back up after it’s released. This keeps serotonin available between nerve cells for longer and increases serotonin signaling.
Common examples of SSRIs include:
- Citalopram
- Escitalopram
- Fluoxetine
- Paroxetine
- Sertraline
Like other types of antidepressants, SSRIs don’t work right away. Some people may notice an improvement in symptoms within the first couple of weeks, while the full effect can take several weeks.
SSRIs are commonly used for depression and anxiety disorders, including conditions such as generalized anxiety disorder and panic disorder. They are also used for obsessive-compulsive disorder (OCD) and certain related disorders.
What are SNRIs and how do they work?
SNRI stands for serotonin-norepinephrine reuptake inhibitor. SNRIs block the reuptake of serotonin and norepinephrine, which increases signaling involving both chemical messengers.
Norepinephrine is a chemical messenger in the brain that plays a role in alertness, attention, thinking, and the body’s response to stress. Some SNRIs have a stronger effect on serotonin, while others have a stronger effect on norepinephrine.
Examples of SNRIs include:
- Desvenlafaxine
- Duloxetine
- Levomilnacipran
- Venlafaxine
SNRIs are used for depression and anxiety disorders, including generalized anxiety disorder and panic disorder. They may also be used for OCD. Some SNRIs are also used for chronic pain conditions, including certain types of nerve pain.
If you’re hesitant about medication: It’s okay to bring specific concerns about side effects, timing, or safety to a prescriber. Getting answers can help you better understand what to expect before making treatment decisions.
What are the differences between SSRIs and SNRIs?
When comparing SSRI vs SNRI medications, the main difference is that SSRIs mainly affect serotonin, while SNRIs affect both serotonin and norepinephrine. This can lead to some differences in side effects and the conditions they are used to treat, although there’s a lot of overlap because both affect serotonin.
For example, some SNRIs can raise blood pressure or heart rate and may be more likely to cause side effects such as dry mouth or constipation. SNRIs may also be used for certain chronic pain conditions, which can occur along with depression or anxiety.
Research comparing antidepressants does not identify one medication as the best choice for everyone. Individual medications within each class differ in effectiveness, side effects, and tolerability, so a health care provider may weigh those factors along with your symptoms and health history when considering treatment.
Comparing the side effects of SSRIs and SNRIs
SSRI and SNRI medications have similar side effect lists, with some key differences. Some people have few or no side effects, while others may experience one or more. Some side effects may ease or go away as your body adjusts to a new medication or dose, but serious reactions are also possible.
Below are side effects linked to each class, but they don’t include every possible side effect. If you develop severe or bothersome side effects, contact your health care provider.
Possible side effects of SSRIs
- Nausea
- Headache
- Sexual dysfunction
- Sleep disturbances
- Dry mouth
- Diarrhea or loose stools
- Sweating
- Tremor
- Weight changes
- QT prolongation, a change in the heart's electrical activity, with certain SSRIs (uncommon)
- Serotonin syndrome (uncommon)
Possible side effects of SNRIs
- Nausea
- Dizziness
- Sweating
- Dry mouth
- Constipation
- Headache
- High blood pressure
- Increased heart rate
- Sexual dysfunction
- Serotonin syndrome (uncommon)
Antidepressants may raise the risk of suicidal thoughts or behaviors in certain younger people. If you have thoughts of suicide, contact the 988 Suicide & Crisis Lifeline at 988.
If you or someone you know is struggling or in crisis, help is available. Text or call 988 or chat 988lifeline.org. Support is available 24/7.
How a provider may choose between an SSRI and an SNRI
When comparing an SSRI versus SNRI for depression, the choice is individualized. When considering an SSRI vs SNRI, a prescriber may consider your symptoms, health history, other medications, past treatment response, and any ongoing health conditions.
For example, a prescriber may consider an SNRI for someone living with both depression and chronic nerve pain because some SNRIs are also used to treat nerve pain.
Make sure to check with a qualified medical professional before starting, stopping, or adjusting your dose. Abruptly stopping SSRIs or SNRIs can cause withdrawal symptoms such as dizziness, digestive upset, fatigue, and changes in mood.
BetterHelp offers psychiatry services through their psych platform as an additional care option alongside therapy. Eligible adults can connect virtually with licensed psychiatric providers for psychiatric evaluations and ongoing care, which may include medication management when clinically appropriate.
Medication management, with insurance options
$26 average copay for eligible members*
Connect with a psychiatrist*Based on finalized paid psychiatry visits with a copay. Insurance availability, coverage, and costs vary by state, plan, provider network, and provider availability.
Why would an SSRI or SNRI be prescribed for anxiety or depression?
Brain chemicals such as serotonin and norepinephrine help carry signals involved in mood and stress. SSRIs and SNRIs change how these chemical messengers work in the brain and may help reduce symptoms of depression or anxiety. When comparing an SNRI versus SSRI for anxiety or depression, both are commonly prescribed options, but the specific choice depends on individual factors.
How therapy and medication can work together
Medication and therapy can work together as part of a broader treatment plan. Using both approaches may help address anxiety or depression in different ways.
SSRIs and SNRIs affect chemical signaling in the brain, while therapy can help you build coping skills and change unhelpful thought or behavior patterns. BetterHelp can connect you with a licensed therapist online, which may make it easier to fit sessions into your schedule.
Takeaway
When comparing an SSRI versus an SNRI for anxiety or depression, the main difference is that SSRIs primarily affect serotonin, while SNRIs affect serotonin and norepinephrine. A licensed medical professional can help weigh your symptoms, health history, other medications, and possible side effects when making treatment decisions.
BetterHelp’s psychiatry and medication management care addresses a range of mental health needs (e.g. anxiety, depression, ADHD, etc.) by connecting members to providers who prescribe from a defined list of commonly prescribed medications (excluding controlled substances)*. *Medication availability and coverage may vary by member location, clinical appropriateness, and individual pharmacy/insurance benefits. Prescribing decisions are made by the treating clinicians. We do not guarantee that any specific medication will be prescribed or covered by a member’s insurance plan. Controlled substances are not prescribed.
Can SSRIs work immediately?
Not usually. Some people may notice improvement within the first couple of weeks, but it can take several weeks to see the full effects of an SSRI.
What’s the difference between an SNRI and a SSRI?
SSRIs mainly affect one chemical messenger in the brain (serotonin), while SNRIs affect two (serotonin and norepinephrine). Both are treatment options for depression and anxiety disorders, but their side effects and other uses can differ.
Who can prescribe an antidepressant?
Antidepressants are prescribed by qualified medical professionals who have prescribing authority. A licensed medical provider can evaluate your individual needs and discuss whether medication may be part of your treatment plan.
This article is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Medication decisions should be made with a licensed healthcare professional who can consider your individual symptoms, health history, current medications, and treatment goals. Do not start, stop, or change any medication without guidance from a qualified healthcare professional. If you are experiencing a medical emergency or symptoms that feel urgent or life-threatening, call emergency services or seek immediate medical care.
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This article provides general information and does not constitute medical or therapeutic advice. Mentions of diagnoses or therapy/treatment options are educational and do not indicate availability through BetterHelp in your country.
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