Do Antidepressants Cause Weight Gain?

Antidepressants can cause weight gain in some people, but not everyone, and the risk differs by medicine. Mirtazapine and some older tricyclic antidepressants are more often linked to gain, while bupropion is more often linked to little change or loss. Depression itself also changes appetite and weight. This article explains why weight can change, which medicines are involved, what to track, and when to talk with your prescriber.

Do antidepressants cause weight gain? What the evidence suggests

Weight gain is a recognized side effect of some antidepressants, but it is not a certainty with any of them. Many people take an antidepressant for months or years with little change in weight. Others notice gain, and a few lose weight. Several factors contribute, and the mechanism is not fully understood.

MedlinePlus lists weight gain or loss among the possible side effects of antidepressants and notes that side effects vary by medicine and by person (MedlinePlus: Antidepressants). Comparative reviews of individual antidepressants against others, such as Mirtazapine versus other antidepressive agents for depression, look at differences in side effects between drugs, and mirtazapine is often associated with increased appetite and weight gain.

Why weight can change with depression treatment

Depression itself affects weight

Depression can reduce appetite in some people and increase it in others. When mood improves on treatment, appetite often returns toward your usual pattern. That can look like medicine-related gain even when the medicine is not the main driver. Sleep, activity level and stress eating can also shift as mood changes.

Ways a medicine may contribute

Researchers have proposed several ways some antidepressants may affect weight, including increased appetite, stronger cravings, and changes in how the body handles energy. Medicines that act on histamine receptors, for example, are often associated with sedation and increased appetite. None of these explanations is settled, and the effect probably differs from person to person.

Other things happening at the same time

Thyroid conditions, other medicines, menopause, pregnancy, and changes in diet or activity can all change weight. If your weight shifts noticeably, your clinician can consider these along with your antidepressant.

Which antidepressants are more or less linked to weight change

Patterns below are general. Your own experience may differ, and the dose and length of treatment can matter.

• Mirtazapine: often associated with increased appetite and weight gain, as described in the comparative review linked above.
• Tricyclic antidepressants (such as amitriptyline and nortriptyline): are associated with weight gain in some people.
• SSRIs (such as sertraline, escitalopram, paroxetine, fluoxetine): effects vary. Some people gain weight over longer treatment, and paroxetine has been linked to gain more often than some other SSRIs in comparative research, so ask your prescriber how this applies to you. See the reviews of sertraline and escitalopram for how they compare with other options.
• SNRIs (such as duloxetine and venlafaxine): effects vary, and many people see little change. See the duloxetine review.
• Bupropion: more often associated with little change or modest weight loss. For how it differs from SSRIs, see our article Bupropion or an SSRI: How Do These Antidepressants Differ?
• Agomelatine: not available in the US, but included in comparative research (Agomelatine versus other antidepressive agents).

For a general overview of one common SSRI, see Sertraline (SSRIs): Uses, Side Effects, and What to Know.

How much and how quickly weight can change

Weight change varies widely. Comparative reviews mostly describe differences between medicines rather than one number that fits everyone, and some individuals gain more than others. Change can appear gradually over weeks to months, and for some people it shows up with longer treatment. Because timing differs, a steady trend matters more than a single weigh-in.

How to notice a change and what to track

Because weight can drift slowly, it helps to have a starting point. Consider noting your weight, appetite, cravings, sleep and activity when you begin a new antidepressant, then checking in periodically. Bring those notes to follow-up visits. A pattern is more useful to a clinician than a single reading.

Tell your clinician about changes in appetite, swelling in the legs or face, or unusual tiredness. Weight change with these symptoms can have causes unrelated to the antidepressant, such as thyroid or heart conditions.

What to do if you are worried about weight on an antidepressant

Do not change the dose or stop the medicine on your own. Stopping suddenly can cause withdrawal-like symptoms and may allow depression to return. Our article What Happens If You Stop an Antidepressant Suddenly? explains this in more detail.

Instead, tell your prescriber about your concern so they can decide what is appropriate. Options they may discuss include:

• Reviewing whether weight change is linked to the medicine, to improving mood, or to something else.
• Reviewing the dose, switching to a different antidepressant, or adding another treatment. The evidence for each option varies, and any change belongs under their guidance.
• Referring you to a dietitian or discussing activity and sleep habits. Many people can work on weight with changes in eating, activity and sleep, though results vary. MedlinePlus offers general information on weight control and body weight.
• Checking for other contributors, such as thyroid function or other medicines.

Individualized decision tools exist to help clinicians weigh side effects, including weight change, against benefits when choosing a medicine (Individualized antidepressant therapy in patients with major depressive disorder).

Special situations to mention to your clinician

Teens and young adults

Antidepressants carry a boxed warning, the strongest type of label warning, about increased suicidal thoughts and behaviors in children, teens and young adults, especially early in treatment or after dose changes. Weight and appetite changes in teens are worth raising, and MedlinePlus has information on teen depression. If your mood is getting worse, or you have new agitation, restlessness or severe trouble sleeping after starting or changing a dose, contact your prescriber the same day. If suicidal thoughts appear, call or text 988 right away.

Eating disorders

If you have had an eating disorder, or worry that weight concerns are driving unhealthy eating, tell your clinician. Concern about weight is a common reason people stop medicine, and support is available. The product label lists a current or past diagnosis of bulimia or anorexia nervosa as a contraindication to bupropion because of seizure risk. Bupropion is not a weight-loss medicine, and your prescriber decides whether it fits you. Fainting, chest pain, or a very slow or irregular heartbeat in someone with a possible eating disorder can signal medical instability and needs emergency care. See MedlinePlus on eating disorders.

Serious reactions after starting or changing a medicine

Serotonin syndrome is an uncommon but serious reaction that can occur after starting an antidepressant, raising a dose, or adding another medicine. Features can include agitation or confusion with fever, heavy sweating, tremor, muscle stiffness or jerking, diarrhea, or a fast heartbeat. Go to the emergency room or call 911 for high fever, severe muscle rigidity, confusion, a seizure or a very fast heartbeat, rather than driving yourself. Milder symptoms such as tremor, sweating or diarrhea after a new medicine or dose change can be early signs, so call your prescriber or pharmacist the same day. If those symptoms worsen, or combine with fever, stiffness, confusion or a fast heartbeat, treat it as possible serotonin syndrome and call 911.

Call 911 for a seizure, fainting with a racing or irregular heartbeat, chest pain, or trouble breathing after taking an antidepressant. If you or someone else may have taken more antidepressant than prescribed, call Poison Control at 1-800-222-1222 right away, even if there are no symptoms, because some overdoses can look mild at first and then worsen suddenly. Call 911 if the person has severe drowsiness or trouble waking.

Pregnancy

If you are pregnant or planning pregnancy, talk with your prescriber before changing any medicine. MedlinePlus has background on pregnancy and medicines.

Other conditions

Antidepressants are also used for some types of chronic pain and for seasonal depression. Weight effects may depend on the medicine chosen. See chronic pain and seasonal affective disorder.

Weight, health and not giving up on treatment

Untreated depression carries its own health risks, and weight is only one part of the picture. Many people find a medicine that helps their mood without much change in weight, sometimes after trying more than one. If weight is a concern for you, tell your prescriber early so it can be part of the decision from the start.

If you have thoughts of harming yourself, call or text the 988 Suicide and Crisis Lifeline at 988, or call 911 if you are in immediate danger.

When to Seek Medical Care