Beyond Prozac: The Most Commonly Prescribed Antidepressants

Every day, one out of six Americans takes a psychiatric medication, according to a 2017 study published in the Journal of the American Medical Association (JAMA). Twelve percent of these prescription drugs are antidepressants, medications that literally can be a lifesaver for people dealing with the symptoms of major depressive disorder—symptoms that range from sadness and loss of interest in things they once loved to do to extreme feelings of helplessness and even thoughts of suicide.

When you think about antidepressants, the first one that may pop into your head is Prozac (fluoxetine). It's still the best option for many people, but since it was approved by the U.S. Food and Drug Administration (FDA) in 1987, Prozac has been joined by a variety of other antidepressants. If you're considering taking an antidepressant, understanding how the most popular ones work can help you and your doctor decide which might work best for you.

Selective Serotonin Reuptake Inhibitors (SSRIs)

Prozac belongs to a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs). Serotonin is a neurotransmitter that's present in the gut and in the brain. Neurotransmitters are chemicals that help send messages from the end of nerve fibers to other nerves, or to muscles or other structures.

In the brain, low levels of serotonin have been associated with depression and anxiety as well as panic disorders and obsessive-compulsive behavior. Low levels of serotonin in the gut have been associated with irritable bowel syndrome, osteoporosis, and even cardiovascular disease.

 SSRIs do exactly what the name describes: They prevent ​the reuptake (movement back into the nerve endings) of serotonin, making more of the chemical available. In other words, SSRIs relieve depression by boosting low levels of serotonin in the brain.

The Five Most Popular SSRIs

Before SSRIs, there were two main classes of antidepressants—monoamineoxidase inhibitors (MAOIs) and tricyclics.

Both of these types of medications had more potential side effects than SSRIs and were more dangerous if someone accidentally took too much, so it's easy to see why there's been an increase in the types of SSRIs to choose from.

Most SSRIs are very similar in regards to how well they work, although there may be subtle differences that can make one a better choice for you than another. It takes a while for all SSRIs to build up in the body enough to have an effect on symptoms, however, so it can several weeks or even months of trial-and-error to find the particular drug and dosage that will do you the most good.

The side effects of various SSRIs can vary a bit as well, but in general, you may experience any of a few common and relatively minor temporary ones, such as nausea, diarrhea, headaches, dizziness, dry mouth, sweating, and trembling. As for more annoying and potentially dangerous side effects, some people gain weight after they start taking an antidepressant, although sometimes it's not the drug itself but rather improved appetite and a renewed appreciation for eating that puts on the pounds.

Other people find taking an antidepressant puts a damper on their sex lives: Men might have trouble getting an erection, for example, and women may have a hard time reaching orgasm, so that can be an important consideration if you're in an intimate relationship.

People taking an SSRI may find the drug causes them to feel panicky and nervous; some folks have thoughts of hurting themselves or even commiting suicide. Adolescents are especially at risk for this and should be monitored very closely. It's important to wean off of most antidepressants slowly. If you suddenly stop taking one you can have withdrawal symptoms, such as mood swings, dizziness, flu-like symptoms, and headaches.

• Prozac (fluoxetine). Again, Prozac is still one of the most popular SSRIs. It's one of the only ones that the FDA has approved for children and teenagers to use.
• Celexa (citalopram). Studies show Celexa works as well as other SSRIs and has similar side effects. One important thing to know about this antidepressant is that taking high doses of it has been associated with a rare heart rhythm problem.

• Zoloft (sertraline). Zoloft is highly effective, although some people find it's more likely than other SSRIs to cause diarrhea.
• Paxil (paroxetine). You might be more likely to have sexual side effects if you choose Paxil over other antidepressants. It's also linked to a higher risk of sweating.
• Lexapro (escitalopram). Along with Prozac, Lexapro is one of the only SSRIs that's been approved by the FDA for teenagers to use.

Other Antidepressants

Other common antidepressants belong to a class of drugs called serotonin and norepinephrine reuptake inhibitors (SNRIs). These inhibit the reuptake of two neurotransmitters: serotonin and norepinephrine. One of the most commonly prescribed SNRIs is Effexor (venlafaxine), which is as effective as other antidepressants in treating MMD, but does have a higher rate of causing nausea and vomiting, and may increase blood pressure and heart rate.

The SNRI Cymbalta (duloxetine) also can increase blood pressure, but the bigger concern with this drug is that in some people it can lead to liver failure, so if you have any sort of liver disease it could be a dangerous choice for you. The same is true if you drink a lot of alcohol.

There's one other commonly prescribed antidepressant that doesn't fit into either category, Wellbutrin (bupropion), which works by acting on the neurotransmitter dopamine. It has a lower risk of sexual side effects. In fact, some doctors prescribe Wellbutrin along with another SSRI to help counter low libido.

Sources:

Consumer Health Choices. "Using Antidepressants to Treat Depression: Comparing Effectiveness, Safety, and Price."

Mayo Clinic. "Antidepressants: Selecting the One That's Right For You." 

Michael Camilleri, M.D. "Serotonin in the Gastrointestinal Tract." Curr Opin Endocrinol Diabetes Obes. 2009 Feb; 16(1): 53–59.

Thomas J.Moore, AB; Donald R. Mattison, MD, MS. "Adult Utilization of Psychiatric Drugs and Differences by Sex, Age, and Race." JAMA Intern Med. 2017;177(2):274-275. doi:10.1001/jamainternmed.2016.7507.