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 can be life-saving 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.

The most commonly used antidepressants in the study were:

• Zoloft (sertraline hydrochloride)
• Celexa (citalopram hydrobromide)
• Prozac (fluoxetine hydrochloride)
• Desyrel (trazodone hydrochloride)
• Lexapro (escitalopram oxalate)
• Cymbalta (duloxetine hydrochloride)

Perhaps the most recognizable among them is Prozac (fluoxetine). It's still the best option for many people, but since it was approved by the Food and Drug Administration (FDA) in 1987, Prozac has been joined by a variety of other antidepressant medications. 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.

There are many different types of medications available to treat depression. These include:

• Selective serotonin reuptake inhibitors (SSRIs)
• Serotonin and norepinephrine reuptake inhibitors (SNRIs)
• Atypical antidepressants
• Tricyclic antidepressants (TCAs)
• Monoamine oxidase inhibitors (MAOIs)
• Other medications or combinations of antidepressants

In a report issued by the National Center for Health Statistics, 12.7% of people in the United States over the age of 12 reported taking antidepressant medication in the previous month. This research also found that antidepressant use had grown by 64% between 1999 and 2014, increasing from 7.7% in 1999-2002 to 12.4% in 2011-2014. 

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 (IBS), 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.

Before SSRIs, there were two main classes of antidepressants: monoamine oxidase inhibitors (MAOIs) and tricyclics (TCAs). 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.

Some of the most commonly prescribed SSRIs include:

• Prozac (fluoxetine): Prozac is still one of the most popular SSRIs in the United States. It's one of the only ones that the FDA has approved for children and teenagers to use. The 2017 antidepressant use study found that a little over 11% of respondents reported taking Prozac for depression.
• Celexa (citalopram): Studies show that 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. An estimated 14% of respondents reported that they were taking this medication.
• Zoloft (sertraline): Zoloft is highly effective, although some people find it's more likely than other SSRIs to cause diarrhea. Zoloft is the most commonly prescribed antidepressant; nearly 17% of those survey in the 2017 antidepressant use study reported that they had taken this medication.
• 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. While paroxetine did not make the list of the 10 most commonly prescribed psychiatric drugs, it remains a popular choice for some people.
• Lexapro (escitalopram): Along with Prozac, Lexapro is one of the only SSRIs that's been approved by the FDA for teenagers to use. Around 8% of those surveyed reported that they had taken Lexapro.

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 leads to the gain.

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 may have thoughts of hurting themselves or committing suicide. Adolescents are especially at risk and should be monitored closely.

If and when you and your doctor decide to stop your medication, 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.

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.

The SNRIs that are available are:

• Strattera (atomoxetine)
• Pristiq (desvenlafaxine)
• Cymbalta (duloxetine)
• Fetzima (levomilnacipran)
• Savella (milnacipran)
• Ultram (tramadol)
• Effexor (venlafaxine)

While Strattera is an SNRI, it is used as a non-stimulant to treat ADHD, not depression or anxiety.

One of the most commonly prescribed SNRIs is Effexor (venlafaxine), which is as effective as other antidepressants in treating depression, 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.

In the 2017 study on psychiatric drugs, Cymbalta was the most commonly prescribed SNRI drug, with 7% of respondents reporting that they had taken this type of medication.

Tricyclics were among the first antidepressants. While they have been largely replaced by SSRIs, SNRIs, and other antidepressants, TCAs can still be a good option in cases where people have not responded to other types of antidepressants.

Types of tricyclics that are available include:

• Elavil (amitriptyline)
• Asendin (amoxapine)
• Norpramin (desipramine)
• Silenor (doxepin)
• Tofranil (imipramine)
• Pamelor (nortriptyline)
• Vivactil (protriptyline)
• Surmontil (trimipramine)

Tricyclics work by blocking the absorption of serotonin and norepinephrine. By preventing the reuptake of those neurotransmitters, it increases serotonin and norepinephrine levels in the brain, which can help to improve mood and relieve depression. 

No type of TCA medication made the top 10 list of the most commonly prescribed psychiatric drugs.

Atypical antidepressants do not fit into the other antidepressant categories and include:

• Wellbutrin (bupropion)
• Desyrel (trazodone)
• Trintellix (vortioxetine)
• Remeron (mirtazapine)

Of the atypical antidepressants, Wellbutrin is one of the most commonly prescribed. It works by acting on the neurotransmitter dopamine. An estimated 24 million prescriptions for bupropion were given in the year 2017. It has a lower risk of sexual side effects. In fact, some doctors prescribe Wellbutrin along with another SSRI to help counter low libido.

Monoamine oxidase inhibitors (MAOIs) were the first type of medication developed to treat depression. They have been largely replaced by newer antidepressants that are safer and have fewer side effects. MAOIs are rarely prescribed given the significant risk associated with eating certain foods containing tyramine, which can cause a hypertensive crisis.

Some of the most commonly prescribed MAOIs include:

• Marplan (isocarboxazid)
• Nardil (phenelzine)
• Parnate (tranylcypromine)
• Emsam (selegiline)

MAOIs work by inhibiting monoamine oxidase, an enzyme that breaks down serotonin, dopamine, and norepinephrine, which are all neurotransmitters that control mood. This results in higher levels of these chemicals in the brain which helps improve mood and reduce anxiety.