SNRIs vs SSRIs: How To Know Which is Right For You

In this article, we do a depression and anxiety medication comparison to help people better understand their treatment options.

We will explore the similarities and differences of SNRIs vs SSRIs, including how they work and who they are best suited for.

What Are SSRIs and SNRIs?

The most commonly used medications include: 

• Selective serotonin reuptake inhibitors (SSRIs) 
• Serotonin and norepinephrine reuptake inhibitors (SNRIs)

Atypical antidepressants and some other older medications work differently, and are better suited for people who have certain types of mental health conditions, don’t respond to SSRIs or SNRIs, or have certain genetic traits. These other medications include: 

• Tricyclic antidepressants (TCAs)
• Adrenergic alpha-2 receptor antagonists
• Monoamine oxidase (MAO) inhibitors
• Selective noradrenaline reuptake inhibitors
• Selective noradrenaline/dopamine reuptake inhibitors
• Melatonin receptor agonists
• Serotonin 5-HT2C receptor antagonists
• Medications that don’t belong to any particular group, including lithium, buproprion, tianeptine, trazodone, agomelatine, St. John’s wort, and esketamine

A longtime theory of the cause of mental health concerns is that people have a chemical imbalance, or too little of the amount of the neurotransmitter serotonin.

However, research has shown that this isn’t the case. Depression or anxiety cannot simply be attributed to low levels of one chemical. However, we do know that neurotransmitters are involved in the symptoms of many mental health conditions. We also know that many psychiatric medications do work, and researchers are still uncovering the mechanisms of how they do so. The brain is an incredibly complex organ, and exciting research to help us better understand it is underway. 

Medications are thought to work by impacting some of the neurotransmitters that play a key role in the body’s functioning and health, including: 

• Serotonin: Aids in regulating mood, sleep, appetite, and perception of pain.
• Norepinephrine: Plays a role in the body’s stress response and also impacts alertness and mood regulation.
• Dopamine: Involved with pleasure, motivation, and the reward system.

How SSRIs Work

SSRI antidepressants are thought to work by blocking the mechanism in neurons that transports serotonin, leading to less reuptake and higher levels of that neurotransmitter available for use. 

Conditions Commonly Treated With SSRIs

The conditions treated with SSRIs include:

• Major depressive disorder 
• Generalized anxiety disorder
• Panic disorder
• Agoraphobia
• Social anxiety disorder
• Obsessive-compulsive disorder 
• Panic disorder 
• Post-traumatic stress disorder 
• Premenstrual dysphoric disorder 
• Eating disorders
• Autism spectrum disorders

How SNRIs Work

SNRI antidepressants are thought to work by blocking the mechanism in neurons that transports both serotonin and norepinephrine. 

Conditions Commonly Treated With SNRIs

The conditions treated with SNRIs include:

• Major depressive disorder 
• Generalized anxiety disorder
• Attention-deficit hyperactivity disorder 
• Obsessive-compulsive disorder
• Chronic pain conditions
• Fibromyalgia

SNRI vs SSRI: Similarities and Key Differences

The key difference between SSRIs and SNRIs is that only SNRIs involve norepinephrine, while they both impact serotonin. 

Effectiveness

Both SSRIs and SNRIs are effective, and while they can both be used to treat some disorders like major depressive disorder, they are used to treat different types of other mental health conditions.

For example, for people with bipolar depression, SNRIs are often used for short-term courses of treatment, and they are less likely to cause rapid mood cycling than SSRIs. However, prolonged use carries the possibility of triggering episodes of mania or hypomania. 

When medications match the condition they are best suited to treat, people often experience relief from their symptoms, increased energy and motivation, and a better quality of life. 

Side Effects

SSRIs are tolerated much better with fewer side effects than older antidepressants. They can still cause side effects, including irregular heartbeat, sexual dysfunction, digestive system problems, and dry mouth.

SNRIs have the potential for side effects, including constipation, nausea, dry mouth, drowsiness, and fatigue.

Some of the less common side effects include muscle problems like involuntary twitching - also called extrapyramidal symptoms, tachycardias- or fast heartbeat, rash, hyponatraemia - or a low concentration of sodium in the blood, cataracts, thoughts of suicide - especially in adolescents, and serotonin syndrome. 

• If you or someone you know is experiencing thoughts of suicide, please call or text the Suicide and Crisis Hotline at 988.

Serotonin syndrome symptoms include disorientation, cardiovascular problems, and muscle tremors. While it is rare, severity can range from uncomfortable to potentially deadly.

This is why it is crucial to tell your doctor about all the medications and supplements you are taking to prevent this. If you suspect you may have serotonin syndrome, please seek medical attention as soon as possible. Here are some additional symptoms to watch out for:

• Irregular heartbeat
• Very high temperature
• Feeling confused 
• Diarrhea 
• Nausea or vomiting
• Muscle rigidity
• Dilated pupils
• Shivers or chills
• Seizures

Additionally, it is advised that people avoid many substances and drugs while taking SSRIs and SNRIs due to the risk of harmful interactions, such as alcohol, cannabis, NSAIDs, St. John’s Wort, and some foods and beverages. 

An important note is that approximately 46% of people who take antidepressants experience emotional blunting, or the inability to feel emotions like happiness, sadness, anger, and more. This was found to frequently be more of a symptom of the depression itself, rather than a side effect of the medication. Ensure you tell your provider if this is something you experience.

Discontinuation

If one decides to stop taking an antidepressant medication, consultation with your healthcare provider is essential. Once the body becomes used to a medication, discontinuing it can be an uncomfortable process.

As many as 1 in 5 people experience what is called discontinuation syndrome, which can include symptoms such as difficulty sleeping, nausea, flu-like symptoms (such as body aches), anxiety, restlessness, and sensory disturbances (such as feelings of being shocked, burning, or tingling). Even when tapered gradually, some people can still experience symptoms. 

Symptoms can range from mild, moderate, to severe, with the most severe symptoms being associated with stopping the medication suddenly. It has been found that one medication in the SNRI group, venlafaxine, had the worst symptoms, while a medication in the SSTI group, fluoxetine, had the mildest symptoms.

It’s important to note that discontinuation syndrome isn’t dangerous, and symptoms will cease without medical intervention.

Which Is Better for Anxiety or Depression?

There isn’t a one-size-fits-all approach to finding the best medication. Both SSRIs and SNRIs have been found to effectively treat both general anxiety disorder and major depressive disorder. There are certain conditions for which each is better suited. 

Clinicians will decide which medication is right for their patient by conducting a comprehensive medical exam and reviewing the patient's history.

Important considerations they will assess for are medical history, the presence of more than one mental health condition, alcohol and recreational substance use, pregnancy or if you intend to become pregnant, side effects, cost of the medication, and the clinician’s experience prescribing the medication to other patients. 

Switching Between SSRIs and SNRIs

People do sometimes switch between depression medication types, and this is most often considered when one is tried and found to be ineffective for the patient. People are usually tapered off one medication before starting another, but it is also possible to use a different medication to aid in the tapering process. 

Caution is needed when switching. If there isn’t enough time to come off one medication before starting another, this puts people at risk of serotonin syndrome. 

Changing medications should always be done under the supervision of a medical professional, and it’s vital to ensure they know all the medications and supplements one is taking to avoid potential harmful interactions. 

Questions to Ask Your Healthcare Provider

Communication with your healthcare provider is vital. Come prepared with a list of topics and concerns you would like to discuss, along with any questions. Be ready to share your personal health information, like medications and current and previous health concerns.

You can also ask about timelines and how soon you can expect to see results. It’s also important to review how your progress will be monitored to ensure you are getting the treatment you need. Patients should feel empowered to play an active role in making their healthcare decisions. 

Takeaway

Both SSRIs and SNRIs are effective treatment options for anxiety. Recovery from mental health concerns like depression and anxiety is possible. Accurate diagnosis by a licensed healthcare clinician matters for effective treatment and management of these conditions. 

If you or your loved one is looking for mental healthcare or crisis support and prevention, reach out to us at Willow Health today. We offer same-day or next-day appointments with both a psychotherapist and a psychiatric medication clinician, who can assess your needs and identify a plan for individualized care. 

Sources

Relationship of neurotransmitters to the symptoms of major depressive disorder - PubMed 

The serotonin theory of depression: a systematic umbrella review of the evidence | Molecular Psychiatry 

Commonly prescribed antidepressants and how they work | NIH MedlinePlus Magazine 

Treatment of anxiety disorders - PubMed 

Selective Serotonin Reuptake Inhibitors and Adverse Effects: A Narrative Review 

Serotonin norepinephrine reuptake inhibitors: a pharmacological comparison - PubMed 

Effects of antidepressant use and anxiety on psychiatric rehospitalization in bipolar depression - PubMed 

SSRIs and SNRIs: A review of the Discontinuation Syndrome in Children and Adolescents - PMC 

Antidepressants - NHS 

Emotional blunting with antidepressant treatments: A survey among depressed patients - ScienceDirect