A large new study looking at eight different common antidepressants shed light on exactly how much of a weight gain risk certain drugs pose compared with others and how much weight people on these medicines could gain while taking them.

On the other hand, the SSRIs escitalopram (Lexapro, Cipralex) and paroxetine (Paxil) were each associated with a 10 to 15 percent higher risk of significant weight gain than sertraline in the first six months of use.

“There are some differences in weight gain between different antidepressants, even those that are in the same category — like SSRIs,” says lead study author Joshua Petimar, ScD, an assistant professor of population medicine at the Harvard Pilgrim Health Care Institute and Harvard Medical School in Boston. “Our results can be useful for doctors who are considering several options for a patient, and when the doctor or patient are concerned about excess weight gain.”

Escitalopram and Paroxetine Linked to the Most Weight Gain After 6 Months

They compared all of the medications with sertraline, which was the most commonly prescribed antidepressant in the study.

“We found that on average, escitalopram and paroxetine were associated with the greatest average six-month weight gain compared with sertraline — about 1 [additional] pound,” says Petimar. “By contrast, users of bupropion lost about a half-pound compared with users of sertraline.”

People taking citalopram, duloxetine, or venlafaxine on average gained between one-quarter and three-quarters more pounds than people taking sertraline, says Petimar.

Weight Gain More Likely When Taking Antidepressants Long-Term

When considering weight gain linked to antidepressants, it’s important to look at how medications affect weight in the long run, says Manish Jha, MD, a psychiatrist with UT Southwestern’s O’Donnell Brain Institute in Dallas.

“Weight gain with antidepressants is more likely with long-term use,” says Dr. Jha, who was not involved in the study. “Given the often chronic nature of depression, most individuals will need to take antidepressants for the long-term.”

Participants taking sertraline, for example, saw an average weight gain of 0.5 pounds at six months, but that rose to 3.2 pounds after two years, says Petimar. In comparison, bupropion takers shed about 0.25 pounds after six months, yet gained an average of 1.2 pounds after two years.

Those taking escitalopram or paroxetine experienced an average weight gain of 1.4 pounds after six months, says Petimar. After two years, people taking escitalopram gained an average of 3.6 pounds, while paroxetine users gained about 3 pounds.

There were no clinically significant differences in the amount of weight gained with these drugs after two years of use, notes Petimar. Why that’s important: “Weight gain earlier on might discourage some people taking antidepressants from continuing them, even if they are effective at treating their symptoms, because they want to avoid this side effect,” says Petimar.

For instance, a patient might be dissuaded from taking paroxetine over sertraline due to a greater short-term risk of weight gain. But, their decision might change when looking at weight changes over a period of two years, when the amount of weight gain for paroxetine and sertraline was about the same, Petimar says.

Weight Gain Can Vary From Person to Person

For some patients, weight gain might be the factor that tips the scale when deciding whether to take an antidepressant, according to Jami Woods, MD, an assistant professor of psychiatry at University of California in Riverside.

“It’s a risk-benefit decision, but in balance, treating your mental and emotional health is still more important than any bit of weight gain you might get from these drugs,” says Dr. Woods, who was not involved with the study. Plus, there are several ways to help counteract weight gain, including regular exercise and sticking to a nutritious diet.

It’s also important to note that weight gain in response to a medicine is very individual. “Some patients gain a lot of weight on any kind of medication and others don’t,” she says. “Genetics may play the largest role. Some who feel better on an antidepressant will become more active and lose weight while others won’t.”

Although not addressed in this study, Woods points out that dosage may play a role as well, with higher dosages leading to more weight gain than lower ones.

“Ultimately, if a patient is experiencing unwanted weight gain that they suspect is related to their use of antidepressants, they should speak with their doctor about this so that they can come up with a solution to counter this side effect,” says Petimar.