The main types of antidepressants are SSRIs, SNRIs, atypical antidepressants (such as bupropion), tricyclic antidepressants and MAOIs, plus newer options like esketamine for hard-to-treat depression. Each type affects brain chemicals such as serotonin, norepinephrine or dopamine in a different way, and each has its own side effect profile. Most take several weeks to work, and finding the right fit is a process you and your prescriber work through together.
This guide explains how each class works, common side effects and what to know before starting or stopping a medication. It is general information only. Never start, stop or change a medication without talking to your health care provider.
How Antidepressants Work
According to Cleveland Clinic, antidepressants change the way your brain uses certain chemical messengers, called neurotransmitters, to better regulate mood and behavior. They are used for depression, and many are also used for anxiety disorders, PTSD, obsessive-compulsive disorder, panic disorder, some chronic pain conditions and more.
The National Institute of Mental Health (NIMH) notes that antidepressants usually take 4 to 8 weeks to work. Problems with sleep, appetite and concentration often improve before mood lifts, so it’s important to give a medication time before judging whether it helps.
The Main Types of Antidepressants
SSRIs (Selective Serotonin Reuptake Inhibitors)
Cleveland Clinic notes that SSRIs are the most commonly prescribed antidepressants. The Mayo Clinic’s SSRI guide explains that they block the reabsorption (reuptake) of serotonin in the brain, leaving more serotonin available to carry messages between nerve cells. FDA-approved SSRIs for depression include:
- Citalopram (Celexa)
- Escitalopram (Lexapro)
- Fluoxetine (Prozac)
- Paroxetine (Paxil)
- Sertraline (Zoloft)
Mayo Clinic notes that health care providers often start by prescribing an SSRI. It also notes that possible side effects include upset stomach, headache, sleep problems, dry mouth, nervousness, sexual problems and appetite changes. Many side effects ease after the first few weeks.
SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors)
Cleveland Clinic explains that SNRIs raise levels of both serotonin and norepinephrine, which help with mood, stress and alertness. The Mayo Clinic guide to choosing an antidepressant lists examples such as duloxetine, venlafaxine and desvenlafaxine.
Atypical Antidepressants
Atypical antidepressants don’t fit neatly into the other groups. Mayo Clinic lists bupropion, trazodone and mirtazapine as examples. NIMH describes bupropion as an NDRI (norepinephrine-dopamine reuptake inhibitor). Mayo Clinic notes that bupropion is less likely than many other antidepressants to cause sexual side effects.
Tricyclic Antidepressants (TCAs)
Tricyclics, such as amitriptyline, are an older class. Mayo Clinic notes they tend to cause more side effects than newer medicines, so they generally aren’t prescribed unless an SSRI or another option hasn’t helped.
MAOIs (Monoamine Oxidase Inhibitors)
MAOIs boost brain chemicals by blocking an enzyme that breaks them down, according to Cleveland Clinic. Mayo Clinic says they are usually prescribed when other medicines haven’t worked, because they can have serious interactions with certain foods and medicines and require following a diet that limits certain foods.
NMDA Receptor Antagonists
Cleveland Clinic describes this newer group as medicines that can work quickly to improve mood and are typically used when other options haven’t worked. Esketamine nasal spray is one example. According to its FDA prescribing information, it is approved for treatment-resistant depression in adults and must be given in a certified health care setting where patients are monitored for at least two hours. Learn more in our article on treatment-resistant depression.
How Your Provider Chooses an Antidepressant
There’s no single “best” antidepressant, and no way to know in advance exactly how you will respond. Comparing the types of antidepressants is only the starting point. Mayo Clinic says providers consider factors such as:
- Your specific symptoms
- Possible side effects and which ones matter most to you
- Whether a medicine worked for you or a close relative in the past
- Interactions with other medicines and supplements
- Pregnancy or breastfeeding
- Cost and insurance coverage
Mayo Clinic also notes that medicine combined with talk therapy is often more effective than either alone. A psychiatrist can be especially helpful if you have tried several medicines. Our guide to psychiatrist vs. therapist explains the difference. Some of the same medicines are also used for anxiety; see our overview of anxiety medications.
Important Safety Information
All types of antidepressants come with some risks to know about. Share a full list of your medicines and supplements with your prescriber, and ask what side effects to watch for.
Suicide Risk Warning for Young People
NIMH explains that antidepressants carry an FDA “black box” warning because some children, teens and young adults under 25 may have an increase in suicidal thoughts or behavior when taking them. Watch closely for new or worsening symptoms and contact the prescriber right away if they appear.
Serotonin Syndrome
Taking an antidepressant with other substances that raise serotonin, such as certain migraine medicines or St. John’s wort, can cause serotonin syndrome. NIMH describes it as rare but potentially life-threatening. Cleveland Clinic lists symptoms such as confusion, muscle stiffness, fever and seizures. It needs emergency care, so call 911 if you notice these signs.
Stopping an Antidepressant
Antidepressants aren’t addictive, but stopping suddenly can cause what Mayo Clinic calls antidepressant discontinuation syndrome. Symptoms can include dizziness, headache, nausea, tiredness, flu-like symptoms, trouble sleeping, irritability and “electric shock” sensations. Your provider can help you lower the dose gradually over time if you need to stop.
Frequently Asked Questions
What is the most common type of antidepressant?
SSRIs are the most commonly prescribed type, according to Cleveland Clinic. Mayo Clinic notes they generally cause fewer bothersome side effects than older antidepressants.
How long do antidepressants take to work?
Most take about 4 to 8 weeks to reach their full effect, according to NIMH. Some symptoms, like sleep and appetite, may improve sooner.
What if my antidepressant isn’t working?
Talk with your prescriber. Options may include adjusting the medicine, switching to a different type or adding therapy. Don’t stop on your own.
What should I do if I feel worse or have thoughts of suicide?
Contact your prescriber right away. If you are in crisis, call or text the 988 Suicide & Crisis Lifeline, which is free, confidential and available 24/7. Call 911 in an emergency.
Get Help for Depression in Lancaster, PA
Medication works best as part of a complete plan. At The Ranch Pennsylvania Outpatient Services, our mental health treatment programs combine psychiatric evaluation and medication management with CBT, DBT and individual, group and family therapy, in both a partial hospitalization program and an intensive outpatient program. Explore our depression resources or learn about depression treatment in Pennsylvania. You can verify your insurance online, and our admissions team is available 24/7. Calls are free and confidential.
