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Key takeaways
SSRIs and SNRIs are prescribed for depression, anxiety, and other mental health disorders, with SSRIs increasing serotonin levels and SNRIs increasing both serotonin and norepinephrine levels in the brain.
Both SSRIs and SNRIs are effective for treating depression and anxiety, with their efficacy depending on the individual’s response and specific health conditions.
Common side effects of both SSRIs and SNRIs include drowsiness, dizziness, dry mouth, and sexual dysfunction, with SNRIs potentially causing more nausea and increased blood pressure.
SSRIs and SNRIs interact with many drugs, including anticoagulants and other serotonergic drugs, increasing the risk of bleeding and serotonin syndrome, and they carry a black box warning for increased risk of suicidal thoughts and behaviors in young people.
Drug overview & main differences | Conditions treated | Efficacy | Insurance coverage and cost comparison | Side effects | Drug interactions | Warnings | FAQ
If you’re diagnosed with depression, you may be prescribed an antidepressant like an SSRI (selective serotonin reuptake inhibitor) or an SNRI (serotonin and norepinephrine reuptake inhibitor). These medications are often prescribed to be taken on a daily basis, and they are approved to help relieve symptoms of depression and other mental health disorders like anxiety. To understand the difference between these two classes of drugs, it’s important to understand the possible biochemistry behind depression and anxiety.
It’s not completely understood how depression or anxiety arises. However, neurotransmitters like serotonin, dopamine, and norepinephrine are believed to play a role in regulating mood. Also known as chemical messengers, these neurotransmitters relay nerve signals and messages in the brain, and research suggests that an imbalance of these neurotransmitters can lead to changes in mood and mental health. Antidepressants like SSRIs and SNRIs target this imbalance to relieve symptoms of depression and other mental health disorders.
But what exactly are SSRIs and SNRIs, and what’s the difference between them? Continue reading to learn more about the differences and similarities between SSRIs and SNRIs.
What are the main differences between SSRIs vs. SNRIs
SSRIs, or selective serotonin reuptake inhibitors, work by blocking the reuptake of serotonin. By blocking the reuptake, or reabsorption, of serotonin, SSRIs can help increase levels of serotonin in the brain. This mechanism of action is believed to help relieve symptoms of depression. Depending on the medication prescribed, some SSRIs are approved in adults, young adults, and children. They are usually available in different forms like tablets, extended-release tablets, capsules, and oral suspension.
Also known as serotonin-norepinephrine reuptake inhibitors, SNRIs work by blocking the reuptake of both serotonin and norepinephrine in the brain. Unlike SSRIs, SNRI medications help increase levels of serotonin and norepinephrine in the brain. These drugs may also be prescribed to adults, adolescents, and children, and they are usually administered as an oral tablet, capsule, extended-release tablet, or extended-release capsule.
| Main differences between SSRIs and SNRIs | ||
|---|---|---|
| Drug class | Selective serotonin reuptake inhibitor | Serotonin and norepinephrine reuptake inhibitor |
| Brand/generic status | Brands and generic versions available | Brands and generic versions available |
| What are examples of medications in this drug class? | Lexapro (escitalopram) Zoloft (sertraline) Prozac (fluoxetine) Celexa (citalopram) Luvox (fluvoxamine) Paxil (paroxetine) |
Effexor XR (venlafaxine) Pristiq (desvenlafaxine) Cymbalta (duloxetine) Fetzima (levomilnacipran) |
| What form(s) does the drug come in? | Oral tablets Oral capsules Extended-release tablets Oral suspension |
Oral tablets Oral capsules Extended-release tablets Extended-release capsules |
| What is the standard dosage? | Depends on the drug prescribed and the condition being treated | Depends on the drug prescribed and the condition being treated |
| How long is the typical treatment? | Long-term treatment as prescribed by a healthcare provider | Long-term treatment as prescribed by a healthcare provider |
| Who typically uses the medication? | Adults, adolescents, and children | Adults, adolescents, and children |
Conditions treated by SSRIs and SNRIs
SSRIs and SNRIs treat similar mental health conditions. Both classes of antidepressants treat major depressive disorder, or depression. Certain SSRIs like Zoloft (sertraline) and Paxil (paroxetine) are approved to treat depression associated with menstruation, or premenstrual dysphoric disorder. Prozac (fluoxetine) is an SSRI approved to treat depressive episodes associated with bipolar disorder when taken with another drug called olanzapine.
SSRIs and SNRIs are also approved to treat different forms of anxiety, such as social anxiety disorder (social phobia), generalized anxiety disorder, and panic disorder. Some SSRIs, like Prozac (fluoxetine), are approved to treat bulimia. Sibutramine, known under different brand names like Reductil, is an SNRI that was approved for bulimia but was discontinued from the market. Now, SNRIs are sometimes used off-label to treat bulimia.
SNRIs are FDA-approved to treat certain types of chronic pain that affect the muscles, joints, and nerves. Cymbalta (duloxetine) is approved to treat diabetic neuropathy, or nerve pain associated with diabetes. It is also approved to treat muscle and joint pain.
| Condition | SSRIs | SNRIs |
| Major depressive disorder (MDD) | Yes | Yes |
| Generalized anxiety disorder (GAD) | Yes | Yes |
| Obsessive-compulsive disorder (OCD) | Yes | Off-label |
| Panic disorder (PD) | Yes | Yes |
| Post-traumatic stress disorder (PTSD) | Yes | Off-label |
| Social anxiety disorder (SAD) | Yes | Yes |
| Premenstrual dysphoric disorder (PMDD) | Yes | Off-label |
| Bulimia nervosa | Yes | Off-label |
| Depressive episodes associated with bipolar disorder | Yes | Off-label |
| Diabetic neuropathy | No | Yes |
| Fibromyalgia | No | Yes |
| Chronic musculoskeletal pain | No | Yes |
Are SSRIs or SNRIs more effective?
SSRIs and SNRIs are both effective treatment options for depression and other mental health disorders. The most effective antidepressant depends on the individual, the condition being treated, and other conditions they may have. Consult a healthcare provider to determine the best choice as therapy with antidepressant medications is highly individualized.
One meta-analysis that assessed 15 randomized clinical trials found that SSRIs and SNRIs are similarly effective for treating depression. Some statistical methods favored SNRIs over SSRIs, but no major differences in clinical effectiveness were found between these types of medications. Another study found that SSRIs and SNRIs are similarly effective for treating anxiety disorders with no significant differences in how well they work.
According to a meta-analysis from JAMA Psychiatry, SSRIs and SNRIs were found to be more effective than placebo for children and adolescents. However, SNRIs are not considered a first-line antidepressant for children because of the potential for adverse effects and less evidence supporting their use in children.
The information provided here is meant for educational purposes only. Seek medical advice from a healthcare provider when determining the best antidepressant for you.
Coverage and cost comparison of SSRIs vs. SNRIs
SSRIs and SNRIs come in both generic and brand-name forms. Most insurance plans, including Medicare prescription insurance plans, help cover the cost of antidepressants. However, the copay can differ across different plans.
The average cost of antidepressant medications will also depend on the drug, strength, and quantity prescribed. Savings options are available to help cover the out-of-pocket costs for SSRIs and SNRIs. A prescription discount card, like the SingleCare discount card, can help provide savings on prescription medications.
| SSRIs | SNRIs | |
| Typically covered by insurance? | Yes | Yes |
| Typically covered by Medicare Part D? | Yes | Yes |
| Quantity | Depends on the drug prescribed | Depends on the drug prescribed |
| Typical Medicare copay | Depends on the drug prescribed | Depends on the drug prescribed |
| SingleCare cost | Depends on the drug prescribed | Depends on the drug prescribed |
Common side effects of SSRIs vs. SNRIs
SSRIs and SNRIs have similar side effects. The most common side effects of SSRIs and SNRIs are drowsiness (tiredness), dizziness, dry mouth, blurred vision, trouble with urination, constipation, and trouble sleeping. These medications can also cause nervousness, weight gain, nausea, vomiting, and diarrhea.
Another common side effect of SSRIs and SNRIs is sexual problems, including sexual dysfunction, decreased sex drive, and impotence. Side effects with antidepressants can affect everyone differently, although they are usually mild and temporary for most people.
SNRIs may cause more nausea, dry mouth, and insomnia than SSRIs. SNRIs can also increase norepinephrine levels, which may cause increased blood pressure. People with high blood pressure may need to monitor blood pressure levels while taking an SNRI.
| SSRIs | SNRIS | |||
| Side Effect | Applicable? | Frequency | Applicable? | Frequency |
| Drowsiness | Yes | – | Yes | – |
| Dizziness | Yes | – | Yes | – |
| Dry mouth | Yes | – | Yes | – |
| Blurred vision | Yes | – | Yes | – |
| Trouble urinating | Yes | – | Yes | – |
| Constipation | Yes | – | Yes | – |
| Trouble sleeping | Yes | – | Yes | – |
| Nervousness | Yes | – | Yes | – |
| Nausea | Yes | – | Yes | – |
| Vomiting | Yes | – | Yes | – |
| Diarrhea | Yes | – | Yes | – |
| Weight gain | Yes | – | Yes | – |
| Sexual problems | Yes | – | Yes | – |
| Increased blood pressure | No | – | Yes | – |
Frequency is not based on data from a head-to-head trial. This may not be a complete list of adverse effects that can occur. Please refer to your doctor or healthcare provider to learn more.
Source: FDA
Drug interactions of SSRIs vs. SNRIs
Because they work in similar ways, SSRI and SNRI antidepressants can interact with many of the same drugs. SSRI and SNRI medications have direct effects on platelets and interfere with platelet aggregation. Anticoagulants, or blood thinners, can also interfere with platelets and the blood clotting process. Therefore, it is recommended to avoid taking anticoagulants, like warfarin, with SSRIs or SNRIs due to an increased risk of bleeding. If taken together, the use of these medications should be monitored.
There is an increased risk of serotonin syndrome when SSRIs or SNRIs are taken with other serotonergic drugs, like opioids, triptans, or monoamine oxidase inhibitors (MAOIs). These antidepressants should also be avoided with other antidepressants, like tricyclic antidepressants, and certain herbal supplements, like St. John’s wort.
| Drug | Drug Class | SSRIs | SNRIs |
| Warfarin Apixaban Dabigatran Rivaroxaban Edoxaban Betrixaban |
Anticoagulants | Yes | Yes |
| Tramadol Hydrocodone Oxycodone Codeine |
Opioids | Yes | Yes |
| Sumatriptan Almotriptan |
Triptans | Yes | Yes |
| Phenelzine Isocarboxazid |
Monoamine oxidase inhibitors (MAOIs) | Yes | Yes |
| Amitriptyline Nortriptyline |
Tricyclic antidepressants | Yes | Yes |
| St. John’s wort | Herbal supplement | Yes | Yes |
*This may not be a complete list of all possible drug interactions. Consult a doctor with all medications you may be taking.
Warnings of SSRIs and SNRIs
There is a black box warning for suicidal thoughts and behavior while taking an SSRI or SNRI antidepressant. The risk of new-onset or worsened suicidal thoughts and behaviors is increased in young adults, adolescents, and children taking antidepressants. Suicidality should be monitored in these groups of people.
Both SSRIs and SNRIs can increase levels of serotonin in the brain, which can lead to an increased risk of serotonin syndrome when taken with other serotonergic drugs. Serotonin syndrome is a potentially life-threatening condition that is associated with symptoms like increased sweating, rapid heart rate, agitation, and confusion.
The use of SSRIs or SNRIs may increase the risk of abnormal bleeding, especially when taken with anticoagulant drugs like warfarin. Those with a history of bleeding events, like stomach ulcers, may need to use caution while using an SSRI or SNRI.
Tell a doctor if you are pregnant or breastfeeding before using an SSRI or SNRI. You should also tell your healthcare provider if you have other medical conditions, including liver problems, before starting treatment. Antidepressants like SSRIs or SNRIs may activate manic episodes in those with bipolar disorder.
Frequently asked questions about SSRIs vs. SNRIs
What are SSRIs?
SSRIs, or selective serotonin reuptake inhibitors, are antidepressant medications used to treat major depressive disorder and anxiety. They are also approved to treat other mental health disorders like bulimia. SSRI medications are generally taken as a daily oral tablet.
What are SNRIs?
SNRIs, or serotonin-norepinephrine reuptake inhibitors, are antidepressants that can treat major depressive disorder and anxiety disorders. They are available as oral tablets or capsules that can be taken on a daily basis. Certain SNRIs can also be prescribed to treat certain types of chronic pain.
Are SSRIs and SNRIs the same?
SSRIs and SNRIs are similar classes of antidepressants, but they are not the same. Although both antidepressants can help relieve symptoms of depression, they work in different ways. SSRIs selectively block the reuptake of serotonin to increase serotonin levels. SNRIs block the reuptake of both serotonin and norepinephrine to increase serotonin and norepinephrine levels in the brain.
Is SSRIs or SNRIs better? / Are SSRIs or SNRIs better for anxiety?
Both SSRIs and SNRIs are similarly effective for treating depression and anxiety. The best antidepressant is the one that works best for you and depends on the condition being treated. Certain SNRIs are approved to treat chronic nerve and musculoskeletal pain, and these antidepressants may be preferred for someone that has both depression and chronic pain. Seek a healthcare provider for medical advice on whether an SSRI or SNRI is better for your medical condition.
Can I use SSRIs or SNRIs while pregnant?
Most SSRIs and SNRIs are not known to carry a risk of birth defects. Paxil, or paroxetine, may be associated with an increased risk of heart abnormalities in an unborn fetus and is not usually recommended during pregnancy. Certain SSRIs and SNRIs may be continued throughout pregnancy, although the benefits and risks should be assessed with the help of a healthcare provider.
Can I use SSRIs or SNRIs with alcohol?
It is not usually recommended to drink alcohol while taking antidepressants like an SSRI or SNRI. Mixing antidepressants with alcohol may increase the risk of certain adverse effects, like drowsiness and dizziness. Some healthcare providers may allow you to consume alcohol in moderation during treatment, but you should avoid drinking alcohol until you’re fully aware of the medication’s effects.
What is safer: SSRIs or SNRIs?
These types of medications are generally safe to take. Both SSRIs and SNRIs can cause similar side effects, such as dizziness, drowsiness, dry mouth, and sexual dysfunction. However, some people may find that they don’t experience any side effects while taking these medications. Side effects are usually mild and go away on their own as the body adjusts to the drug.
