Selective Serotonin Reuptake Inhibitors: What Are SSRIs and How Do They Work?
If life has been getting on top of you and your emotional and mental well-being have been taking a hit, the topic of antidepressants may have crossed your mind. If so, even light research into medication may lead to the question, What is an SSRI?
Selective serotonin reuptake inhibitors (“SSRIs” for short) are a type of medication most commonly used to treat depression. However, they can also be used to get the symptoms of a variety of mental health conditions under control. SSRIs are usually a “first-line” form of treatment for emotional issues due to their safety, low risk of side effects, and ability to be tolerated by many people.1
Yet, despite their wide ability to treat different conditions and people, SSRIs don’t work for everyone. If you’re considering antidepressants to treat a mental health condition, Mission Connection can make sure you get the right fit for your needs.
This page can also help by explaining:
- What SSRIs are, including how they work
- The variety of conditions SSRIs can be used to treat
- How long SSRIs take to work
- The common side effects of SSRIs
- Questions to ask your mental health provider about SSRIs
What Is an SSRI?
Selective serotonin reuptake inhibitors (SSRIs) are known as “second-generation” antidepressants. This is because, while they’re equally as effective in treating symptoms of depression as older tricyclic antidepressants and monoamine oxidase inhibitors, they carry the risk of far fewer side effects.2
Because SSRIs don’t cause as many side effects as other antidepressants, doctors and mental health professionals often turn to them as the first port of call when considering medication treatment.
SSRIs first started to be used for treating depression in the late 1980s, with the introduction of the prototype SSRI, fluoxetine (commonly known under the brand name “Prozac”). Fluoxetine is the 19th most prescribed drug in the U.S.; it’s still frequently used to treat a variety of conditions, such as depression, anxiety, OCD, and panic attacks.3 However, nearly 40 years after the evolution of fluoxetine, there are now considerably more options of SSRIs to choose from based on people’s unique needs and symptoms.
The following list of common SSRIs describes each and what they can be used for.
List of Common SSRIs:
- Fluoxetine (Prozac): Used to treat conditions such as depression, anxiety, obsessive-compulsive disorder (OCD), and panic attacks
- Sertraline (Zoloft): Used to treat depression, OCD, panic disorder, social anxiety, post-traumatic stress disorder (PTSD), and premenstrual dysphoric disorder
- Citalopram (Celexa): Most commonly used to treat major depression, but can also be used off-label to treat a variety of other issues
- Escitalopram (Lexapro): Frequently used to treat depression and anxiety, and is considered to be one of the most easily tolerated antidepressants by both adults and minors
- Paroxetine (Paxil): Similar to other SSRIs, paroxetine is suitable for treating many different mental health conditions
When faced with so many different types of SSRIs, you may be feeling a little confused and overwhelmed. This is to be expected. Yet you don’t have to decide which SSRI is most suitable for your symptoms by yourself. Mental health professionals, such as Mission Connection’s team, can explain the specifics of each medication, including their benefits and possible side effects, as well as how they differ.
To help you further understand whether SSRIs could be right for you, let’s cover how they work to improve the symptoms of mental health conditions.
How SSRIs Work In the Brain
To give full disclosure, there isn’t really a full understanding behind why some people develop mental health issues and others don’t. Mental health conditions are a complex interplay between genetics, environment, and biology. So, how antidepressants work isn’t entirely understood either.
However, it’s possible that mental health conditions create an “imbalance” of neurochemicals in the brain, specifically chemicals called “serotonin” and “norepinephrine.” When these chemicals are low, we experience disturbed sleep, mood, behaviors, and alertness – all of which are associated with different mental health issues.4
How SSRIs work in the brain is that they boost the amount of serotonin. Serotonin is called the “feel-good” chemical because its job is to send messages in the brain. Typically, once serotonin’s message is received by a nerve cell, it gets absorbed. This is where the “reuptake inhibitor” part of SSRIs comes into play; they block the ability of nerve cells to soak up serotonin. As a result, there’s more serotonin available to ferry messages from nerve cell to nerve cell, leading us to feel more positive, alert, and focused, as well as better able to handle emotions.3
It’s good to note that, while the chemical imbalance theory of depression became widely accepted, there’s no real concrete evidence for it being the main cause of mental health issues. Yet antidepressants could still offer relief from symptoms for many people – especially when the root causes of issues are targeted through treatments such as therapy.
Additionally, you may have picked up on how SSRIs help boost one of the brain chemicals responsible for mood – serotonin – but not the other. This is because norepinephrine is targeted by a different antidepressant: SNRIs.
To build your awareness of the right antidepressant for your needs, let’s compare the differences between SSRIs and SNRIs.
SSRI vs SNRI: Knowing the Difference
As mentioned, SSRIs are usually the first port of call when treating conditions such as anxiety and depression, as they typically cause the lowest amount of side effects for people. They work by blocking the brain’s ability to absorb the “happy hormone” serotonin, leading to improved mood, behavior, physical well-being, and overall outlook.
But what if SSRIs don’t work to improve your symptoms? In this case, a medical or mental health professional will likely discuss the option of serotonin norepinephrine reuptake inhibitors (SNRIs).
SNRIs are also second-generation antidepressants, and can be more effective for reducing the symptoms of mental health issues than SSRIs – but could pose the risk of more side effects.5
Along with increasing serotonin, SNRIs also work by boosting norepinephrine. Norepinephrine helps to regulate sleep, attention, memory, and mood. So, improving the availability of this chemical in the brain could help people focus and feel more positive.
However, norepinephrine plays a vital role in the body’s “fight or flight” response, so increased levels could lead to feelings of panic, high blood pressure, and over-alertness in some people. Therefore, SNRIs may not be suitable for people with panic disorders or certain physical conditions.
A medical or mental health professional can talk to you about whether SSRIs or SNRIs may be more appropriate for your needs.
What Conditions Do SSRIs Treat?
What are SSRIs used for? The simplest response to this question is that SSRIs can be used to treat depression and anxiety disorders. However, they can also be used off-label to treat a variety of conditions. Off-label prescribing happens frequently and simply means that a medication can be used to treat issues beyond those for which it was created, like for chronic pain management.6
For instance, an SSRI for OCD is considered to be an established first-line treatment for treating obsessions and compulsions – yet why they work isn’t fully understood.7
In general, SSRIs have FDA approval for treating conditions such as:
- Major depressive disorder
- Generalized anxiety disorder
- Bipolar depression
- Post-traumatic stress disorder (PTSD)
- Social anxiety disorder
- Panic disorders
- Obsessive-compulsive disorder (OCD)
- Treatment-resistant depression
- Premenstrual dysphoric disorder
If you’re considering an SSRI for a condition other than those listed above, Mission Connection can explain off-label medication treatment and whether it’s appropriate for your needs.
How Long Do SSRIs Take to Work?
If a mental health condition is affecting your day-to-day life, you may be understandably eager to see results as soon as possible. However, it’s good to know that the speed of SSRIs’ effects can vary from person to person. We all have different biological makeups, so we respond to medication in unique ways.
For instance, some people might start noticing the effects at the two-week mark, but others might not see a difference until after six weeks.1 The key is not to become discouraged during the waiting period. However, if you notice any adverse side effects (which we describe next), it’s important to monitor these and discuss them with your medical or mental health provider.
What Are Common Side Effects of SSRIs?
Like any medication, antidepressants can have side effects – including SSRIs. Even though they’re considered to be the “lowest risk” antidepressant, it’s still important to monitor any mental or physical shifts after starting the drug. A medical and mental health professional will explain potential side effects to you, but the following information can also give you some insight.
Potential SSRI Side Effects
Common SSRI side effects can vary from person to person and drug to drug, and include:8
- Gastrointestinal issues, such as stomach upset or diarrhoea
- Headache
- Perspiration
- Anxiety and nervousness
- Difficulty sleeping
- Brain “zaps”
- Changes in weight and appetite
- Sexual dysfunction
Some people may experience none of these side effects, while others may get a few of them. Many of these effects go away after you allow your body time to adjust to the increase in serotonin, but if they don’t, your provider may consider switching you to a different med.
There is also a dangerous and far less common side effect that is important to be conscious of when taking SSRIs – serotonin syndrome.
What Is Serotonin Syndrome?
Serotonin syndrome can be a life-threatening consequence of serotonin toxicity or overdose. The frequency of serotonin syndrome is not overly known, as mild cases can be missed or misdiagnosed. SSRI overdose is thought to be the main cause of serotonin syndrome, but it can also come down to combining two different drugs or substances. For instance, taking St.John’s Wort alongside SSRIs can increase the risk of serotonin syndrome.9
Serotonin syndrome symptoms typically develop in a few hours and can include the following signs:
- Confusion
- Agitation
- Restlessness
- Confusion
- Dilated pupils
- Heavy perspiration
- Stiff muscles
- Headache
- Shivering
- Stomach upset
- Fast heart rate and high blood pressure
If you notice these signs, calling your healthcare provider can ensure you get the help you need. However, when serotonin syndrome is life-threatening, it can cause issues such as:
- Seizures
- High fever
- Arrhythmia (irregular heartbeat)
- Tremors
- Loss of consciousness
If you or someone you know shows these serious serotonin syndrome symptoms, you may need to call 911 or visit your local emergency department.
Questions to Ask Your Mental Health Professional About SSRIs
It can be tough to decide whether SSRIs are the right choice for your mental health and well-being. Talking to professionals, such as Mission Connection’s team, can make sure you’re on the right track to improved mental health. The following FAQs and answers could also put your concerns to rest.
What Is the Safest SSRI?
There’s no such thing as the “safest” SSRI for everyone across the board – we all differ mentally and physiologically. However, based on research, citalopram tends to be the SSRI that is most widely tolerated. After citalopram, fluoxetine and sertraline appear to produce the least amount of side effects in people.10
Can You Stop Taking SSRIs Suddenly?
SSRIs work by altering the amount of chemicals in your brain, so stopping them suddenly means that the body and brain may need time to readjust. Depending on how long you’ve been taking antidepressants, what type you’re on, and the dosage, stopping them suddenly could lead to withdrawal symptoms. SSRI withdrawal symptoms can include:12
- Return of emotional and mental symptoms
- Insomnia
- Sweating
- Stomach upset
- Brain jolts (feeling like there’s an electric shock in your head)
- Dizziness
- Agitation
- Flu-like symptoms
Tapering off SSRIs slowly is the best approach for your physical and mental well-being. Mission Connection can create a tapering plan to suit your needs and schedule.
Can SSRIs Make Anxiety Worse?
Truthfully, it is possible for SSRIs to make anxiety worse, especially in the early stages of treatment. However, studies show that the majority of people experience an improvement in anxiety symptoms after the two-week mark.13 If you’re concerned about the impact of SSRIs on your anxiety, it’s best to discuss your symptoms with a mental health professional and monitor your symptoms closely. You can also ask your provider about the best SSRIs for anxiety to alleviate your concerns.
How Do I Know When to Switch SSRIs?
All antidepressants take time to physically and mentally adjust to – and SSRIs are no different. However, if you continue to experience adverse side effects or have no improvement in symptoms after the adjustment period (typically six weeks), it may be worth talking to your provider. Not every medication works for everyone; sometimes, a process of trial and error is needed.
Mission Connection: Supporting You Through Mental Health Care
Finding the right antidepressant for your needs can be challenging; different people can react uniquely to the same substance. Mission Connection is here to make sure that this process goes as smoothly for you as possible.
Our team provides medication monitoring in combination with a variety of treatments and therapies – giving you the best chance at successful and maintained recovery. This is because medication alone doesn’t get to the root of the problem; it works best when combined with therapy options, holistic approaches, and lifestyle changes.
Sometimes life doesn’t stop while you’re trying to look after your mental health. For this reason, Mission Connection can also offer online telehealth services to make sure that your needs are taken care of in a way that fits your schedule.
If you’re ready to talk about Mission Connection’s treatment options or just have more questions to ask about medication, our team is here to help. Contact us today at 866-779-5586 or fill out our confidential contact form.
References
- Chu, A., & Wadhwa, R. (2023). Selective serotonin reuptake inhibitors. In StatPearls. StatPearls Publishing.
- ScienceDirect. (n.d.). Second-generation antidepressant. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/second-generation-antidepressant
- Psychology Today. (n.d.). SSRIs. https://www.psychologytoday.com/gb/basics/ssris
- Blier, P. (2001). Crosstalk between the norepinephrine and serotonin systems and its role in the antidepressant response. Journal of Psychiatry & Neuroscience, 26(Suppl), S3–S10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2553259/
- Medical News Today. (n.d.). SSRI vs. SNRI: Differences, how they work, and side effects. https://www.medicalnewstoday.com/articles/ssri-vs-snri
- Jannini, T. B., Lorenzo, G. D., Bianciardi, E., Niolu, C., Toscano, M., Ciocca, G., Jannini, E. A., & Siracusano, A. (2022). Off-label Uses of Selective Serotonin Reuptake Inhibitors (SSRIs). Current Neuropharmacology, 20(4), 693. https://doi.org/10.2174/1570159X19666210517150418
- Kellner, M. (2010). Drug treatment of obsessive-compulsive disorder. Dialogues in Clinical Neuroscience, 12(2), 187. https://doi.org/10.31887/DCNS.2010.12.2/mkellner
- Ferguson, J. M. (2001). SSRI Antidepressant Medications: Adverse Effects and Tolerability. Primary Care Companion to The Journal of Clinical Psychiatry, 3(1), 22. https://doi.org/10.4088/pcc.v03n0105
- Garel, N., Greenway, K. T., Tabbane, K., & Joober, R. (2021). Serotonin syndrome: SSRIs are not the only culprit. Journal of Psychiatry & Neuroscience : JPN, 46(3), E369. https://doi.org/10.1503/jpn.210001
- Ferguson, J. M. (2001). SSRI Antidepressant Medications: Adverse Effects and Tolerability. Primary Care Companion to The Journal of Clinical Psychiatry, 3(1), 22. https://doi.org/10.4088/pcc.v03n0105
- Haddad, P. (1999). Do antidepressants have any potential to cause addiction? Journal of Psychopharmacology, 13(3), 300–307. https://doi.org/10.1177/026988119901300321
- Gabriel, M., & Sharma, V. (2017). Antidepressant discontinuation syndrome. CMAJ : Canadian Medical Association Journal, 189(21), E747.
- Gollan, J. K., Fava, M., Kurian, B., Wisniewski, S. R., Rush, A. J., Daly, E., Miyahara, S., & Trivedi, M. H. (2011). What Are the Clinical Implications of New Onset or Worsening Anxiety During the First Two Weeks of SSRI Treatment for Depression? Depression and Anxiety, 29(2), 10.1002/da.20917. https://doi.org/10.1002/da.20917
