Atypical antidepressants differ from other classes of antidepressants. Learn what they are and how they work.By Mayo Clinic Staff
Atypical antidepressants are not typical — they don't fit into other classes of antidepressants. They are each unique medications that work in different ways from one another.
Atypical antidepressants ease depression by affecting chemical messengers (neurotransmitters) used to communicate between brain cells. Like most antidepressants, atypical antidepressants work by changing the levels of one or more of these naturally occurring brain chemicals.
Atypical antidepressants affect neurotransmitters including dopamine, serotonin and norepinephrine. Changing the balance of these chemicals seems to help brain cells send and receive messages, which in turn boosts mood.
The Food and Drug Administration (FDA) has approved these atypical antidepressants to treat depression:
- Bupropion (Wellbutrin, others)
- Mirtazapine (Remeron)
- Trazodone (Oleptro)
Common side effects with most antidepressants, including atypical antidepressants, include dry mouth, constipation, and dizziness or lightheadedness. For antidepressants that cause sleepiness, be careful about doing activities that require you to be alert, such as driving a car, until you know how the medication will affect you. Because of the different way atypical antidepressants work, each also has unique characteristics and side effects.
Bupropion may be a good choice if you have low energy caused by depression or if you're trying to quit smoking. It's sometimes prescribed to ease nicotine cravings under the brand name Zyban. Bupropion doesn't cause sexual side effects or weight gain as several other antidepressants do, and it's sometimes prescribed to counter the sexual side effects of another antidepressant. However, bupropion can cause or worsen anxiety in some people. Additional side effects, among others, may include:
- Weight loss
- Nausea and loss of appetite
- Increased heartbeat
Mirtazapine is generally taken before bed because it can make you sleepy. Additional side effects, among others, may include:
- Increased appetite
- Weight gain
- Increased cholesterol and triglycerides
Nefazodone may help ease anxiety as well as depression, but it can make you sleepy. It seems less likely to cause sexual side effects than do some other antidepressants. Additional side effects, among others, may include:
- Low blood pressure
- Blurred vision
Trazodone causes sleepiness and can help with anxiety. Like mirtazapine, it's usually taken at bedtime. It may be prescribed alone or along with other antidepressants to help with sleep. Additional side effects, among others, may include:
- Blurred vision
- Extreme tiredness (fatigue)
- Muscle aches or pains
- Irregular heartbeat
- Sudden drop in blood pressure when standing (orthostatic hypotension)
Atypical antidepressants are safe for most people. However, in some circumstances they can cause problems. For example:
- Bupropion should not be used by people who have a seizure disorder or an eating disorder such as bulimia or anorexia.
- Mirtazapine has been associated with an increase in cholesterol.
- Nefazodone has been linked to liver failure in some people ― don't take it if you already have liver problems.
- Trazodone has been associated with rare cases of priapism — a persistent, usually painful erection not associated with sexual arousal. In rare cases, trazodone has been linked to heart rhythm problems (cardiac arrhythmias), so if you have heart disease, ask your doctor whether this medication is safe for you.
- Vortioxetine may increase the risk of bleeding, especially in people taking other medications that can increase the risk of bleeding.
For antidepressants that cause sleepiness, be careful about doing activities that require you to be alert, such as driving a car, until you know how the medication will affect you.
Other issues to discuss with your doctor before you take an atypical antidepressant include:
- Antidepressants and pregnancy. Talk to your doctor about the risks and benefits of using specific antidepressants. Some antidepressants may harm your baby if you take them during pregnancy or while you're breast-feeding. If you're taking an antidepressant and you're considering getting pregnant, talk to your doctor or mental health professional about the possible risks. Don't stop taking your medication without contacting your doctor first, as stopping might pose risks for you.
- Drug interactions. When taking an antidepressant, be sure to tell your doctor about any other prescription or over-the-counter medications, herbs or other supplements you're taking. Some antidepressants can cause dangerous reactions when combined with certain medications or herbal supplements.
- Serotonin syndrome. Rarely, an antidepressant can cause high levels of serotonin to accumulate in your body. Serotonin syndrome most often occurs when two medications that raise the level of serotonin are combined. These include other antidepressants, certain pain or headache medications, and the herbal supplement St. John's wort. Symptoms of serotonin syndrome include anxiety, agitation, sweating, confusion, tremors, restlessness, lack of coordination and a rapid heart rate. Seek immediate medical attention if you have any of these symptoms.
Most antidepressants are generally safe, but the FDA requires that all antidepressants carry black box warnings, the strictest warnings for prescriptions. In some cases, children, teenagers and young adults under 25 may have an increase in suicidal thoughts or behavior when taking antidepressants, especially in the first few weeks after starting or when the dose is changed.
Anyone taking an antidepressant should be watched closely for worsening depression or unusual behavior. If you or someone you know has suicidal thoughts when taking an antidepressant, immediately contact your doctor or get emergency help.
Keep in mind that antidepressants are more likely to reduce suicide risk in the long run by improving mood.
Atypical antidepressants aren't considered addictive. However, stopping antidepressant treatment abruptly or missing several doses may cause withdrawal-like symptoms. Symptoms will vary depending on how the drug works. This is sometimes called discontinuation syndrome. Work with your doctor to gradually decrease your dose.
People may react differently to the same antidepressant. For example, a particular drug may work better — or not as well — for you than for another person. Or you may have more, or fewer, side effects from taking a certain antidepressant than someone else does.
Inherited traits may play a role in how antidepressants affect you. In some cases, where available, results of special blood tests may offer clues about how your body may respond to a specific antidepressant. However, other variables besides genetics can affect your response to medication.
When choosing an antidepressant, your doctor takes into account your symptoms, any health problems, other medications you take and what has worked for you in the past.
Typically it takes several weeks or longer before an antidepressant is fully effective and for initial side effects to ease up. You may need to try several antidepressants before you find the right one, but hang in there. With patience, you and your doctor can find a medication that works well for you.
June 25, 2016
- Mental health medication. National Institute of Mental Health. http://www.nimh.nih.gov/health/publications/mental-health-medications/complete-index.shtml. Accessed May 14, 2013.
- Hirsch M, et al. Atypical antidepressants: Pharmacology, admininstration and side effects. http://www.uptodate.com/home. Accessed May 14, 2013.
- Depression. National Institute of Mental Health. http://www.nimh.nih.gov/health/publications/depression/index.shtml. Accessed May 14, 2013.
- Fleeman N, et al. Cytochrome P450 testing for prescribing antipsychotics in adults with schizophrenia: Systemic review and meta-analysis. The Pharmacogenomics Journal. 2011;11:1.
- Ables AZ, et al. Prevention, diagnosis and management of serotonin syndrome. American Family Physician. 2010;81:1139.
- Hirsch M, et al. Antidepressant medication in adults: Switching and discontinuing medication. http://www.uptodate.com/home. Accessed May 14, 2013.
- Howland RH. Potential adverse effects of discontinuing psychotropic drugs - Part 2: Antidepressant drugs. Journal of Psychosocial Nursing. 2010;48:9.
- Wellbutrin (prescribing information). Research Triangle Park, N.C.: GlaxoSmithKline; 2013. http://us.gsk.com/products/assets/us_wellbutrin_tablets.pdf. Accessed May 15, 2013.
- Remeron (prescribing information). Whitehouse Station, N.J.: Merck & Co.; 2012. http://www.merck.com/product/prescription-products/home.html. Accessed May 15, 2013.
- Nefazodone hydrochloride (prescribing information). Sellersville, Pa.: Teva Pharmaceuticals; 2012. http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=51ff7db5-aaf9-4c3c-86e6-958ebf16b60f. Accessed May 15, 2013.
- Oleptro (prescribing information). Dublin, Ireland: Angelini Labopharm; 2010. http://oleptro.com/. Accessed May 15, 2013.
- Buss Preszler LK (expert opinion). Mayo Clinic, Rochester, Minn. May 28, 2013.
- Hall-Flavin DK (expert opinion). Mayo Clinic, Rochester, Minn. May 30, 2013.
- What is pharmacogenomics? Genetics Home Reference. http://ghr.nlm.nih.gov/handbook/genomicresearch/pharmacogenomics. Accessed May 30, 2013.