The most commonly prescribed antidepressants today fall into a few major classes: SSRIs, SNRIs, and atypical antidepressants. SSRIs like sertraline (Zoloft) and escitalopram (Lexapro) are the most widely used starting point, but the best fit depends on your symptoms, side effect tolerance, and what else is going on with your health. Here’s a breakdown of each class, what makes them different, and what taking them actually feels like.
SSRIs: The Most Widely Prescribed Class
Selective serotonin reuptake inhibitors work by keeping more serotonin available in the brain. Serotonin is a chemical messenger that helps regulate mood, sleep, and appetite. By preventing the brain from reabsorbing it too quickly, SSRIs give serotonin more time to do its job. The FDA lists seven SSRIs currently approved in the United States:
- Fluoxetine (Prozac)
- Sertraline (Zoloft)
- Escitalopram (Lexapro)
- Citalopram (Celexa)
- Paroxetine (Paxil)
- Fluvoxamine (Luvox)
- Vilazodone (Viibryd)
SSRIs are prescribed for depression, anxiety disorders, and other mood conditions. They’re popular as a first option because they tend to cause fewer and milder side effects than older antidepressants. That said, common complaints include nausea in the first week or two, sexual side effects like reduced desire or difficulty with orgasm, and sometimes weight changes over time. These side effects vary significantly from one SSRI to another, so switching within the class is common if the first one isn’t a good fit.
SNRIs: A Dual-Action Alternative
Serotonin and norepinephrine reuptake inhibitors work on two chemical messengers instead of one. In addition to serotonin, they also increase norepinephrine, which plays a role in energy, alertness, and the body’s pain signaling. This dual action makes SNRIs a frequent choice when depression comes with significant fatigue, difficulty concentrating, or chronic pain. The four FDA-approved SNRIs for depression are:
- Venlafaxine (Effexor XR)
- Duloxetine (Cymbalta)
- Desvenlafaxine (Pristiq)
- Levomilnacipran (Fetzima)
Duloxetine is also approved for certain chronic pain conditions, including fibromyalgia and diabetic nerve pain, which makes it a practical two-for-one option for people dealing with both pain and depression. Side effects overlap with SSRIs (nausea, sexual dysfunction), but SNRIs can also raise blood pressure slightly, so periodic monitoring is typical. Venlafaxine in particular is known for causing noticeable discontinuation symptoms if stopped abruptly, more on that below.
Atypical Antidepressants
This is something of a catch-all category for antidepressants that don’t fit neatly into the other classes. They each work through slightly different brain chemistry pathways, which means they have distinct side effect profiles. That makes them useful alternatives when SSRIs or SNRIs aren’t working well or are causing intolerable side effects.
Bupropion (Wellbutrin) is one of the most popular in this group. It primarily affects dopamine and norepinephrine rather than serotonin. The practical upside: it’s one of the few antidepressants that rarely causes sexual side effects or weight gain. Some people actually experience mild appetite suppression. Bupropion is not a good option for anyone with a seizure disorder or a history of eating disorders like bulimia or anorexia, as it can increase seizure risk.
Mirtazapine (Remeron) works differently again, and it’s known for being sedating. It’s often prescribed when insomnia is a major part of someone’s depression. The tradeoff is that mirtazapine is associated with weight gain and can raise cholesterol levels, so it’s typically monitored more closely over time.
Trazodone is technically an antidepressant, but in practice it’s more commonly prescribed at low doses as a sleep aid. At higher doses it can treat depression, though it causes significant drowsiness. It has been linked in rare cases to a persistent painful erection (priapism), and people with heart disease should discuss its safety with their prescriber because of a small risk of heart rhythm problems.
Tricyclics and MAOIs: Older but Still Used
Tricyclic antidepressants (TCAs) were among the first antidepressants ever developed. Common ones include amitriptyline, nortriptyline (Pamelor), desipramine (Norpramin), doxepin, and imipramine. They’re effective, but they’ve largely been replaced as first-line options because they cause more side effects: dry mouth, constipation, blurred vision, drowsiness, and weight gain are all common. They can also be dangerous in overdose, which is a concern when prescribing to people with suicidal thoughts.
That said, tricyclics still have a real role. They’re sometimes the drug that finally works when newer antidepressants haven’t, and certain tricyclics are also used for chronic pain, migraines, and insomnia. A large study tracking side effects across antidepressants found a 21-beat-per-minute difference in heart rate between some tricyclics and SSRIs, which illustrates why the newer drugs are generally preferred for most people starting treatment.
Monoamine oxidase inhibitors (MAOIs) are the oldest class. They’re rarely prescribed today because they require strict dietary restrictions (certain aged cheeses, cured meats, and fermented foods can trigger dangerous blood pressure spikes) and interact with many common medications. They’re typically reserved for cases where nothing else has worked.
How Long They Take to Work
This is one of the most frustrating parts of starting an antidepressant. Some people notice subtle improvements within the first week or two, often in sleep, energy, or appetite before mood itself lifts. But the full therapeutic effect typically takes 4 to 8 weeks. That’s a long time to wait when you’re struggling, and it’s the main reason people stop taking their medication too early. If you don’t feel meaningfully better after 6 to 8 weeks at an adequate dose, that’s generally the point where your prescriber will consider adjusting the dose or switching to a different medication.
Side effects, frustratingly, often show up before the benefits do. Nausea, headaches, and increased anxiety in the first week are common across most classes. These early side effects usually fade within one to two weeks as your body adjusts.
Stopping an Antidepressant Safely
Antidepressants are not addictive in the way that opioids or benzodiazepines are, but your brain does adapt to them. Stopping suddenly can trigger what’s called discontinuation syndrome. Symptoms typically begin within two to four days and can include flu-like achiness, dizziness, nausea, “brain zaps” (brief shock-like sensations), vivid dreams, and mood swings like irritability or anxiety.
The fix is straightforward: tapering off gradually rather than stopping cold turkey. Each medication and each person requires a different tapering schedule, so this is something to plan with your prescriber. If discontinuation symptoms do hit, resuming the previous dose usually resolves them within about 24 hours, and you can try a slower taper from there. SNRIs, particularly venlafaxine, and paroxetine among the SSRIs are the most likely to cause noticeable withdrawal effects.
A Safety Note for Young People
All antidepressants carry an FDA boxed warning (the most serious type of drug warning) about an increased risk of suicidal thinking and behavior in children and adolescents. This doesn’t mean antidepressants cause suicide. It means that in clinical trials, young people taking antidepressants reported more suicidal thoughts than those on placebo. The risk is highest during the first few months of treatment and whenever the dose is changed. Close monitoring during this period is standard, and families are encouraged to watch for unusual changes in behavior, agitation, or worsening mood. For adults over 24, this elevated risk has not been observed, and for adults over 65, antidepressants appear to reduce suicidal thinking.