Key takeaways

  • While most antidepressants cause weight gain, a few medications — including fluoxetine (Prozac), duloxetine (Cymbalta), and bupropion (Wellbutrin) — may decrease appetite and lead to temporary weight loss during the first months of treatment.
  • Weight changes from antidepressants can happen because some medications affect appetite or metabolism. Mental health conditions like depression can also change eating habits and activity levels, so treating depression with medication may affect weight-related behaviors.
  • Antidepressants are not a weight loss treatment. However, healthcare professionals do consider potential weight changes when prescribing medications for depression and anxiety.

Antidepressants treat mental health conditions like depression and anxiety, but can affect body weight as a secondary effect. Although most can cause weight gain, a few antidepressants, including fluoxetine and duloxetine, may decrease appetite and lead to temporary weight loss.

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Weight gain is a more common side effect of antidepressants than weight loss. A 2019 review of 27 studies reported that, on average, individuals experience a 5% increase in weight after starting antidepressant therapy, while some antidepressants were linked to a 7% weight increase.

Various factors could cause a person to gain weight while on antidepressants:

  • Some antidepressants increase appetite, so a person may be more likely to consume more calories than their body needs.
  • Antidepressants may affect metabolism, causing the body to burn calories more slowly.

Factors that could cause a person to lose weight while on certain antidepressants include:

  • Some antidepressants may decrease appetite, leading a person to consume fewer calories than they burn.
  • Mental health symptoms can include changes in eating behaviors and activity levels. For example, depression sometimes links to reduced activity, snacking, emotional eating, and favoring foods with a higher calorie density. Treating the depression may lessen or stop these behaviors.

A few antidepressants are linked with less weight gain or even weight loss. These include:

  • Bupropion (Wellbutrin): A 2024 study estimated that bupropion led to the lowest weight gain after 6 months compared to 7 other antidepressants, and was linked to a 15% lower risk of weight gain. A 2024 meta-analysis including 25 studies and 22,165 participants also reported that bupropion is linked to weight loss.
  • Fluoxetine (Prozac): A 2022 review concluded that in adults with overweight or obesity, taking 60 milligrams (mg) of fluoxetine daily could lead to an average weight loss of 2.7 kilograms (kg) — equivalent to almost 6 lb — during the first 6 months of treatment. There was no weight-loss effect among people taking low doses for a longer duration.
  • Duloxetine (Cymbalta, Irenka, Drizalma Sprinkle): An older 2006 study found that people taking duloxetine for major depressive disorder lost weight in the short term but gained a small amount during longer-term treatment. The same 2024 study that compared antidepressants reported that duloxetine was linked to higher estimated weight gain than 4 other medications. It also reported that, alongside escitalopram and paroxetine, duloxetine was linked to a 10% to 15% risk of at least a 5% weight gain.

It is common for side effects such as weight loss to stabilize as the body adjusts to the medication.

Also, it is still possible to gain weight from other factors while taking an antidepressant commonly linked to weight loss or stable weight — it’s just that it may be less likely for the antidepressant to contribute to weight gain itself.

Some researchers describe weight gain as one of the most common side effects of using antidepressants — particularly when they are used long term.

Antidepressant medications that may cause weight gain include:

These older antidepressants may also cause weight gain:

Although it may result in weight loss for some people, fluoxetine (Prozac) can also cause weight gain in others. The effect of this drug on body weight may be dependent on the dosage a person receives and the duration of their treatment.

The Food and Drug Administration (FDA) does not approve antidepressants for weight loss, so doctors do not prescribe them for this use. However, doctors do consider the potential effects on weight when prescribing medications.

Doctors can prescribe medications to help treat overweight and obesity. Some options include:

People with a low or moderate weight may not need to lose weight, and excessive weight loss can be harmful. To maintain a healthy weight, a person should eat a nutritious, well-balanced diet.

This involves avoiding or limiting foods high in fat, salt, and sugar, as they can increase the levels of low-density lipoprotein (LDL) cholesterol and blood glucose.

If a person needs to gain or maintain weight through increasing their calorie intake, they can try to eat meals and snacks consisting of:

  • 5 portions of fruits and vegetables daily
  • whole grain starches and carbohydrates with every meal, including oatmeal, potatoes, cereals, brown rice, whole wheat pasta, and whole grain bread
  • full-fat dairy
  • unsaturated fat sources, such as avocados, olives, nuts, and olive oil
  • fish, eggs, poultry, meat, or other protein sources
  • 6 to 8 glasses of water per day, but not directly before a meal, as this may limit how much a person feels able to eat

Milkshakes with protein powder are a good way to boost calorie intake. People can also snack on nuts, peanut butter toast, yogurt, or fruit between meals.

Antidepressants may cause side effects for some people. The type and severity can depend on factors such as age, gender, and other health conditions. The side effects may lessen as the body adjusts to the medication.

The most common side effects include:

The following side effects are rare and require immediate medical attention:

If someone experiences serious side effects, they should call 911 or visit the emergency room.

If other side effects worsen or cause concern, a person should make an appointment with a doctor.

People under the age of 25 years are at particular risk of suicidal thoughts when they first begin taking antidepressants, though it can happen to anyone taking antidepressants. It may be wise for an individual to tell a friend or family member that they are on antidepressants so that this loved one can check in from time to time.

If antidepressants are causing concerning weight loss, it is important to contact the prescribing doctor.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you’re not in the same household, stay on the phone with them until help arrives.

Weight gain is a common side effect of antidepressants, but a few medications may cause weight loss instead. These medications include bupropion, fluoxetine, and duloxetine.

Some antidepressants may affect appetite, leading to weight changes. A person may also change their activity levels and eating habits due to a mental health condition such as anxiety or depression.

Doctors do not prescribe antidepressants specifically for weight loss, but they will consider an individual’s health needs when selecting a medication.

Antidepressants may cause various side effects. If a person experiences worrying or serious side effects, they should seek medical attention.