Weight changes are a possible side effect of all antidepressants, but some antidepressants are more likely to cause weight gain than others.

Every year, millions of people seek treatment for their depression – whether that’s therapy, medication, or other treatment options, like brain stimulation techniques.

Statistics from the Centers for Disease Control and Prevention (CDC) show that from 2013-2018 alone, over 13% of adults reported taking antidepressants.

Antidepressants are effective at helping improve the symptoms of conditions like depression and anxiety, but they can also cause a wide range of side effects.

One of these potential side effects is weight gain, which can affect upward of 5% of people taking antidepressants, according to research.

One reason why weight gain can happen with medications like antidepressants and antipsychotics is their impact on serotonin levels in the brain. Serotonin is a neurotransmitter that affects your appetite, nutrient absorption, and even insulin secretion.

Antidepressants can also influence other chemicals in the body, like dopamine and histamine, which can impact factors like metabolism, appetite, and eating habits.

Behavioral factors can also play into the weight gain that some people experience when taking antidepressants. Someone who has struggled with a low appetite because of depression, for example, may start eating more during treatment, which can cause weight gain.

At the end of the day, weight gain is a potential side effect of almost any antidepressant. But, a particular medication’s impact on weight varies from person to person.

There are more than just a few types of antidepressants on the market; each antidepressant works on the chemicals in your brain in different ways.

Because of this, different antidepressants can cause various side effects, and some are more likely to cause weight gain than others.

So, here’s a rundown of the different types of antidepressants, including which antidepressants are most likely to lead to weight changes.

Selective serotonin reuptake inhibitors (SSRIs)

Selective serotonin reuptake inhibitors (SSRIs) are a type of antidepressant that raise serotonin levels in the brain by blocking the reabsorption of this neurotransmitter.

SSRIs are the most commonly prescribed type of antidepressant medication. Some common SSRIs include:

Research suggests that SSRIs can cause weight gain. But, studies show somewhat inconsistent results.

For example, research from 2000 found that medications like fluoxetine and sertraline were associated with weight gain.

But a newer study from 2020 found that fluoxetine was actually associated with a decrease in weight rather than an increase.

In the 2020 study, sertraline, along with escitalopram, was associated with weight or body mass increases in children and adolescents.

Serotonin-norepinephrine reuptake inhibitors (SNRIs)

Serotonin-norepinephrine reuptake inhibitors (SNRIs) work in a similar way to SSRIs. But in addition to preventing the reabsorption of serotonin, they also control the uptake of norepinephrine.

While doctors don’t prescribe SNRIs as frequently as SSRIs, they do offer an alternative option for people who can’t tolerate SSRIs well. Some common SNRIs include:

One study from 2014 exploring weight gain with antidepressants found that several SNRIs, including duloxetine and venlafaxine, were associated with weight gain.

But, the study found that these medications were less likely to cause less weight gain than some of the other antidepressants in the study.

Tricyclic antidepressants (TCAs)

Tricyclic antidepressants (TCAs) are another type of antidepressant that increases serotonin and norepinephrine in the brain by preventing their reuptake.

Because TCAs often cause more side effects than SSRIs and SNRIs, doctors usually only prescribe this class of antidepressants after other options haven’t worked. Common TCAs include:

Research suggests that almost all tricyclic antidepressants may result in weight gain when taken both short-term and long-term.

A more recent review from 2015 found that amitriptyline was one of several different antidepressants associated with significant weight gain in clinical trials.

Monoamine oxidase inhibitors (MAOIs)

Monoamine oxidase inhibitors (MAOIs) work by blocking the action of monoamine oxidase (MAO). MAO is an enzyme that breaks down neurotransmitters like serotonin, norepinephrine, and dopamine.

MAOIs were the first antidepressants ever introduced on the market, but they’re often considered a last resort option because of the potential side effects and interactions. Some common MAOIs include:

Doctors rarely prescribe MAOIs anymore, so most research on MAOIs and weight gain is sparse.

Atypical antidepressants

When typical antidepressants aren’t effective at helping alleviate or manage symptoms, atypical antidepressants are another option to consider for treatment. Doctors can also combine these medications with other antidepressants for effectiveness.

Atypical antidepressants work on the neurotransmitters in the brain in various ways, depending on the medication. Common atypical antidepressants include:

Research has shown that several types of atypical antidepressants may cause weight gain.

In the 2015 review mentioned above, two common atypical antidepressants – mirtazapine and olanzapine – were associated with significant weight loss in clinical trials.

In this same review, the researchers noted that bupropion was associated with significant weight loss among study participants.

Antidepressants that cause minimal weight gain

Weight gain is a potential side effect of any antidepressant medication, but some antidepressants are less likely to result in weight gain – and may even result in weight loss.

Some of the antidepressants that appear to cause little to no weight gain include:

  • Atypical antidepressants: bupropion (Wellbutrin)
  • SSRIs: fluoxetine (Prozac) and fluvoxamine (Luvox)
  • MAOIs: isocarboxazid (Marplan) and tranylcypromine (Parnate)
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If you’ve recently decided to start taking antidepressants but are worried about weight gain as a potential side effect, consider contacting your doctor to discuss your concerns.

They can help you find a medication that’s both effective and less likely to result in side effects like weight changes.

If you’ve already been taking antidepressants and have noticed changes in your weight, it can also be helpful to chat with your doctor.

They can recommend dietary and lifestyle changes, such as tracking your calories or increasing your activity, to help you manage any weight changes you’ve been experiencing.