Panic Disorder Treatment How Long Does It Take for Antidepressants to Work? By Sheryl Ankrom, MS, LCPC Sheryl Ankrom, MS, LCPC LinkedIn Sheryl Ankrom is a clinical professional counselor and nationally certified clinical mental health counselor specializing in anxiety disorders. Learn about our editorial process Updated on April 10, 2022 Medically reviewed Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Steven Gans, MD Medically reviewed by Steven Gans, MD Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital. Learn about our Medical Review Board Print Joe Raedle / Getty Images Table of Contents View All Table of Contents What Are Antidepressants? When Different Types Start Working What to Expect Frequently Asked Questions Most antidepressants don't provide instant relief of symptoms related to depression, anxiety, and other conditions for which they're prescribed. Rather, you must take them routinely and consistently for several weeks or even months before you notice changes. Here are a few guidelines on how long antidepressants take to work. What Are Antidepressants? Clinicians frequently prescribe antidepressants to help reduce symptoms of depression, anxiety, obsessive-compulsive disorder (OCD), social anxiety disorder (SAD), agoraphobia, and panic disorder. These medications work by affecting the brain's neurotransmitters—chemical messengers that are responsible for regulating sleep, mood, anxiety, motivation, and other functions and states. Common Classes of Antidepressants and Examples Antidepressant medicines generally fall into a few classes. The medications in each class are similar, but not identical. Selective serotonin reuptake inhibitors (SSRIs): Prozac (fluoxetine); Paxil and Pexeva (paroxetine); Zoloft (sertraline); Celexa (citalopram); Lexapro (escitalopram) Serotonin and norepinephrine reuptake inhibitors (SNRIs): Cymbalta (duloxetine); Effexor XR (venlafaxine); Pristiq (desvenlafaxine); Fetzima (levomilnacipran) Tricyclic antidepressants (TCAs): Tofranil (imipramine); Pamelor (nortriptyline); amitriptyline; doxepin; Norpramin (desipramine) Monoamine oxidase inhibitors (MAOIs): Parnate (tranylcypromine); Nardil (phenelzine); Marplan (isocarboxazid); Emsam (selegiline) Atypical antidepressants: Trazodone; Remeron (mirtazapine); Trintellix (vortioxetine); Viibryd (vilazodone); Wellbutrin SR and Wellbutrin XL (bupropion); and more Most are available in tablet form. Emsam is absorbed through a skin patch. When treating depression, doctors often define "treatment response" as about a 50% decrease in the Hamilton Depression Rating Scale (HAM-D) score compared to the patient's initial (baseline) score. A decrease of 20% to 33% in HAM-D score is often considered the "onset of improvement." How Long Different Types of Antidepressants Take to Work Antidepressants vary by type in the time they take to work, because each class works differently. In any case, you probably won't see significant improvement in your symptoms for several weeks after you begin your antidepressant dosing regimen. Here are a few general guidelines on when you'll likely begin to see some relief from your symptoms, depending on which type of drug you are taking. Biomarkers may lag behind these more subjective responses. Selective serotonin reuptake inhibitors (SSRIs): About six weeksSerotonin and norepinephrine reuptake inhibitors (SNRIs): One to four weeksTricyclic antidepressants (TCAs): Two to four weeksMonoamine oxidase inhibitors (MAOIs): As early as two weeks and up to six What Is a Biomarker? A biomarker (short for "biological marker") is a molecule in the body that signals some condition or process. Healthcare providers and researchers use biomarkers in diagnosis, treatment, and testing—for example, to check how well a cancer treatment is working or to detect high cholesterol. Should I Take My Antidepressant at Night or in the Morning? What to Expect When Starting an Antidepressant Once you start taking your antidepressant, you might feel a bit worse before you feel better. Researchers used to believe that the initial boost in energy an antidepressant sometimes provides explains the increased risk of harmful behaviors. However, newer research on SSRIs (the most commonly prescribed class) indicates that this occurs because antidepressants work on different chemicals in your body, and they each reach their optimum levels at different times. When your antidepressant does start helping, don't stop taking it because you feel better. Stopping it suddenly might mean the return of your symptoms—along with some unpleasant, possibly dangerous, side effects. Possible Side Effects of Antidepressants Common side effects of antidepressants include: Sleep disturbancesHeadachesFatigueDizzinessLightheadednessDry mouthNervousnessIncreased sweatingSexual side effectsBlurred visionNausea These are only some of the side effects you can face while taking an antidepressant. You may experience one or more of these, or none at all. Talk with your healthcare provider about any concerning symptoms. It's important not to stop taking your antidepressant because it's causing side effects or seemingly not working; your body may just need time to adjust. To ease the transition, you might be prescribed a very low dose at first that is gradually increased. These side effects typically subside and become much more manageable over time. Managing Your Condition While Waiting for Results If you have an anxiety diagnosis, your doctor may initially prescribe a benzodiazepine (an anti-anxiety medication) along with your antidepressant. Benzodiazepines allow for a faster sense of symptom alleviation. Benzodiazepines carry a risk for dependence and abuse, so your doctor may take you off this medication once the antidepressant reaches its full benefit. Coping With Side Effects If side effects are persistent and become difficult to manage, consult your doctor about the possibility of changing the dosage or medication to better fit your needs. Beware of Discontinuation Syndrome Never stop taking your antidepressant without consulting your healthcare provider. Discontinuing your medication suddenly can cause antidepressant discontinuation syndrome, a cluster of unpleasant, and in some cases, dangerous effects when your brain chemicals change too quickly. If your clinician decides that a medication change is necessary, they will instruct you on how to taper down safely and as comfortably as possible. Considering a Change in Drug or Dosage Your healthcare provider must balance any medication's potential benefits against its risks and side effects. If you and your clinician believe that you have had an adequate trial of antidepressant therapy without significant improvement or if you find the side effects intolerable, a medication change might be in order. Don't undertake a medication change without your doctor's supervision. Signs Your Antidepressant Isn't Working A Word From Verywell Many people must try several different antidepressants before finding what works best—but most do find relief with the right antidepressant, especially when it's combined with psychotherapy. Always follow your healthcare provider's instructions regarding your antidepressant dosage regimen to maximize its benefits and minimize side effects. Frequently Asked Questions Why does it take so long for antidepressants to work? Many antidepressants, such as SSRIs, are dual-acting. That is, they work on different chemicals in your body, and they each reach their optimum levels at different times. Additionally, your body needs time to adjust to these changing levels of neurotransmitters, the chemical messengers that help regulate sleep, mood, anxiety, motivation, and other functions and states. How do antidepressants work? Antidepressants affect the levels of chemicals in your brain called neurotransmitters. These chemical messengers help regulate sleep, mood, anxiety, motivation, and other functions and states What happens if you miss a day of antidepressants? Depending on the half-life of your specific antidepressant, you might begin to feel sick after just a few hours if you miss a dose. Symptoms vary with the antidepressant and your usual dose, and they run the gamut from irritability and anxiety to fatigue, nausea, and unusual dreams. If you've missed your dose by just a few hours, take it as soon as you remember. If it's closer to the time you'd take it tomorrow, take it then instead. Learn More: Why Do I Feel Sick When I Miss a Dose of My Antidepressant? 11 Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Goodwin GM. 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J Psychopharmacol (Oxford). 1998;12(3):305-13. doi:10.1177/026988119801200311 By Sheryl Ankrom, MS, LCPC Sheryl Ankrom is a clinical professional counselor and nationally certified clinical mental health counselor specializing in anxiety disorders. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit Speak to a Therapist for Panic Disorder Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.