Beyond Prozac: The Most Commonly Prescribed Antidepressants

Antidepressants are among the most frequently prescribed medications in the U.S. From 2015 through 2018, more than 14% of people 12 and older said they took an antidepressant in the last month.

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 a doctor decide which might work best for you.

How Do Antidepressants Work?

There are five major classes of antidepressants, and they all work in different ways:

• Selective serotonin reuptake inhibitors (SSRIs)
• Serotonin and norepinephrine reuptake inhibitors (SNRIs)
  
• Tricyclic antidepressants (TCAs)
• Monoamine oxidase inhibitors (MAOIs)
• Atypical antidepressants

But the one thing all of these antidepressant medications have in common is that they increase the availability of monoamine neurotransmitters in the brain.

In people with depression, the availability of these monoamine neurotransmitters in the brain is characteristically low. Antidepressants work by preventing the reuptake of one or more of these neurotransmitters, thereby increasing their availability.

SSRIs

Prozac belongs to a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs). SSRIs do exactly what the name describes: They prevent ​the reuptake of serotonin, making more of the chemical available. In other words, SSRIs relieve depression by boosting low levels of serotonin in the brain.

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 that the FDA has approved for children and teenagers. 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 antidepressant use study 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 surveyed 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 increased sweating. While paroxetine did not make the list of the 10 most commonly prescribed psychiatric drugs, it remains a good 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 SSRIs to build up in the body enough to have an effect on symptoms. Because of this, it can take several weeks or even months of trial and error to find the particular drug and dosage that will do you the most good.

SNRIs

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:

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

While Strattera is an SNRI, it is used as a non-stimulant medication 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 it.

TCAs

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:

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

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.

MAOIs

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, but there are still several MAOIs available.

Some of the most commonly prescribed MAOIs include:

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

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.

MAOIs are rarely prescribed given the significant risk associated with eating certain foods containing tyramine, which can cause a hypertensive crisis.

Atypical Antidepressants

Atypical antidepressants are those that don't fit into any of the other classes. Doctors often prescribe them if other antidepressants either don't work, or cause unbearable side effects.

Common atypical antidepressants include:

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

Each of these atypical antidepressants influences different neurotransmitters in different ways. Some target dopamine, for example, while others serotonin or norepinephrine. Still, others target a combination of the three. As a result, they have different side effects compared to other antidepressants. For example, compared to other antidepressants, Desyrel is less likely to cause symptoms such as sexual dysfunction, insomnia, or anxiety.

Of the atypical antidepressants, Wellbutrin is one of the most commonly prescribed. It works by acting on the neurotransmitter dopamine affecting energy levels, motivation, and attention. It has a lower risk of sexual and gastrointestinal side effects. In fact, some doctors prescribe Wellbutrin along with another SSRI to help counter low libido.

Common Side Effects of Antidepressants

Antidepressants can improve the symptoms of depression, but, like all medications, they can also cause side effects. The frequency and severity of these side effects vary depending on the class of medication you're taking.

Common side effects of antidepressants include:

• Constipation
• Drowsiness
• Nausea
  
• Sexual dysfunction
• Sleep disturbances
• Weight gain
  

Antidepressants may also increase the risk of suicidal thinking and behavior (suicidality), especially during the first few months of treatment, or when your dose is increased or decreased. Teens and young adults are especially at risk and should be monitored closely.

Side effects tend to be mild and go away as your body adjusts to the medication. If your side effects are severe or last for longer than a few weeks, your prescribing doctor may adjust your dosage or recommend a different antidepressant.

If and when you and a doctor decide to stop your medication, it's important to wean off of most antidepressants slowly. If you suddenly stop taking an antidepressant medication, you can experience withdrawal symptoms, such as mood swings, dizziness, flu-like symptoms, and headaches.