How SSRIs Work: What to Expect When Starting Antidepressant Medication

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Maybe you’ve been feeling low for some time. You may have tried exercising and focusing on your breathing. You are doing all of the right things, but notice yourself making little to no progress. So what should you do next? Well, research has proven that individuals who take part in both medication and talk therapy, experience the best mental health improvements when compared to groups that are taking medication only or talk therapy only (Kamenov et al., 2017). In this article, we will discuss the basic biological mechanism that SSRI’s use to decrease anxiety and depressive symptoms and how CBT therapy can complement medication use.

Many people still ask, “but what about the side effects of medication?” This is indeed an important question that we are going to explore in this article, and it should ultimately be discussed with your medical provider. On the other hand, it is important to consider the other side of the coin. To quote psychiatrist Dr. Daniel Amen: “What are the side effects of not taking medication?” Are your current approaches working? If the answer is no, medication could be the next appropriate step.

Perhaps you use acetaminophen for headaches. Coffee for focus. Chances are, you are already using some form of substance to alleviate pain or enhance performance, which ultimately is improving your quality of life. Medication for anxiety and depression is just that, a substance that influences your brain functioning and your ability to show up everyday at your best.

What Are SSRIs?

SSRIs (Selective Serotonin Reuptake Inhibitors) are one of the most widely prescribed and researched classes of antidepressants (Karami et al., 2025). SSRIs, often referred to as antidepressant medication, are commonly prescribed for both anxiety and depression conditions. Research shows positive outcomes for alleviating symptoms for those with generalized anxiety disorder and major depressive disorder (Cleveland Clinic, 2025b). 

You may have heard of several SSRI’s, such as bupropion (Wellbutrin), Escitalopram (Lexapro) and Sertraline (Zoloft). These are the most common types of medication for anxiety and depression. 

How SSRIs Work in the Brain

SSRIs increase the amount of serotonin that is in your body and brain. Serotonin is a neurotransmitter that affects mood, sleep and energy, and acts as a messenger that carries information between nerve cells in your brain and your body. There is a negative correlation between serotonin and depressive symptoms, meaning the lower someone’s serotonin levels, the higher probability that they will have depressive symptoms (Cleveland Clinic, 2025a).

To ‘inhibit’, means to block something from passing through. A reuptake inhibitor will block the receptor that serotonin passes through to leave your body. This means the serotonin spends a greater amount of time in your brain. SSRI’s effects may take weeks to build (Cleaveland, 2025b). Everyone’s receptivity to medication is somewhat unique, and this creates a task for patients and prescribers to find the right medication and dosage for them, a process often referred to as ‘medication titration’.

What Are SSRI Side Effects?

It is important to have a transparent discussion with your medical provider about the side effects of your medications. SSRIs’ common side effects could include mild nausea, fatigue, sleep changes, dizziness and libido changes (Cleaveland, 2025b). According to Cascade et al., (2009) an estimated 38% of patients taking an SSRI experience at least one side effect, and of those patients, 25% report the symptom interfering with their everyday life.

One factor that many people are concerned about when starting SSRIs is that the body may experience withdrawal-like symptoms when trying to taper off the medication (Yazbek, 2025). However, unlike other, often higher-dependency medications taken for anxiety and depression, such as benzodiazepines and barbiturates, SSRIs carry fewer immediate risks (Yazbek, 2025).

It is imperative that you ask questions and gather as much information from your medical provider as you can prior to starting any medication. You can always book an information seeking appointment, without having to make a definitive decision in the moment. Remember, your medical provider is there to help you, and you have every right to ask about their experiences with prescribing medication and what you should expect when starting an SSRI or any other drug. 

What to Expect When Taking SSRI’s: Early Days and Long-Term Results

The beginning phase of medication titration is trying low doses of different medications, to see which one yields the highest benefits and lowest side effects. Once the right medication has been identified, the body needs time to adjust to the dose increases. It can take up to 12 weeks to notice the benefits of the right dose (Cleaveland, 2025a). 

It is important to note that people's experiences of medication will vary. Different metrics play a role, such as genetic factors, age, and medical history. This makes it even more important to recognize that although you may know someone who has had negative side effects, or positive outcomes, that does not guarantee the same experience for yourself. 

Combining Medication With Talk Therapy

Medication supports neurochemical stability, specifically initiating or making it easier to improve mood, get out of negative slumps and have increased motivation to engage with life (Kamenov et al., 2017). However, medication does not provide the skills and direction for putting that engagement into action. Thus, you may often hear the term ‘skills and pills’ from medical and mental health professionals alike. As mentioned at the top of this article, this two pronged approach is often the most effective for treating anxiety and depression. Cognitive Behavioural Therapy (CBT) can be a highly complementary form of evidence based, talk therapy that supports SSRI use in this ‘skills and pills’ approach. 

By learning CBT’s world-renowned, clinically tested techniques, clients can expect to challenge unhelpful thoughts and behaviours, alleviating symptoms of depression and anxiety (American Psychological Association, 2017). In CBT we introduce people to concepts like the vicious cycle, and learn to use skills such as cognitive reframing. Medication plays a crucial role in reducing the severity of anxiety and depression, making it easier to engage with the CBT techniques. You can learn more about CBT by reading the article Is CBT Right For Me?

Working With Your Provider

Once you have gathered your information and made the decision to start taking an SSRI, continue to communicate as scheduled with your provider while you adjust to the medication. 

If you experience side effects, be sure to let your provider know and do not stop taking the medication without consulting them. Stopping SSRIs abruptly can cause other negative side effects (Jha, et al., 2018), such as anxiety, insomnia or vivid dream, headaches, dizziness, tiredness, irritability, flu-like symptoms, nausea, electric shock sensations, and return of depression symptoms (Mayo Clinic, 2019). The medical provider will work with you to decide if you need to change your dosage amount, frequency or medication altogether.

The best way to get excellent care is to ensure that your medical history and current treatments are in collaboration with healthcare professionals. Make sure you communicate what is happening between your family doctor and any other mental health professionals you may be involved with. 

Final Thoughts

SSRIs are some of the most safe, effective and evidence-based treatments used for anxiety and depression. If you are seeking long term mental health improvement while taking medication, combining SSRIs with talk therapy may be the right choice for you.

Navigating today’s world can be hard. You are not alone. We are here to help provide guidance in the form of medication management and evidence based CBT techniques. Send us a message here for more information.

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References

American Psychological Association. (2017). What is Cognitive Behavioral Therapy? American Psychological Association. https://www.apa.org/ptsd-guideline/patients-and-families/cognitive-behavioral

Cascade, E., Kalali, A. H., & Kennedy, S. H. (2009, February). Real-world data on SSRI antidepressant side effects. Psychiatry. https://pmc.ncbi.nlm.nih.gov/articles/PMC2719451/

Cleveland Clinic medical. (2025a, September 22). Serotonin: What is it, Function & Levels. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22572-serotonin

Cleveland Clinic medical. (2025b, November 18). How do SSRIs work and what do they treat? Cleveland Clinic. https://my.clevelandclinic.org/health/treatments/24795-ssri

Jha, M. K., Rush, A. J., & Trivedi, M. H. (2018). When discontinuing SSRI antidepressants is a challenge: management tips. American Journal of Psychiatry, 175(12), 1176-1184.

Kamenov, K., Twomey, C., Cabello, M., Prina, A. M., & Ayuso-Mateos, J. L. (2017, February). The efficacy of psychotherapy, pharmacotherapy and their combination on functioning and quality of life in depression: A meta-analysis. Psychological medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC5244449/

Karami, H., Mehrizi, R., Effatpanah, M., Rivandi, A., Daroudi, R., Armand, N., & Ghamkhar, L. (2025, February 3). Uncovering antidepressant prescription patterns: A three-year analysis of outpatient trends. BMC psychiatry. https://pmc.ncbi.nlm.nih.gov/articles/PMC11792704/

Kumar, G. K. (2024, September 22). Escitalopram (Lexapro): Uses, side effects, interactions, pictures, warnings & dosing. WebMD. https://www.webmd.com/drugs/2/drug-63990/lexapro-oral/details

Mayo Clinic. (2019, Jan 29). Antidepressant withdrawal: Is there such a thing? Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/depression/expert-answers/antidepressant-withdrawal/faq-20058133

Sean P. Kane, P. (2025, April 15). Escitalopram- Drug Usage Statistics. ClinCalc DrugStats Database. https://clincalc.com/drugstats/Drugs/Escitalopram

Yazbek, C. (2025, January 8). Benzodiazepines vs barbiturates for anxiety treatment. Psyclarity Health. https://psyclarityhealth.com/benzodiazepines-vs-barbiturates-for-anxiety-treatment/