A new study published in The Lancet has found that commonly prescribed antidepressants—while effective in treating depression and anxiety—can cause noticeable physical changes in the body, including variations in weight, heart rate, and cholesterol levels.

The large-scale analysis examined data from over 58,000 participants who took one of 30 different antidepressants or a placebo for an average of eight weeks. Researchers observed what they described as “clinically significant” differences in how each medication influenced metabolism and cardiovascular function.

According to the findings, individuals taking maprotiline gained an average of four pounds, while nearly half of amitriptyline users reported some degree of weight gain. In contrast, agomelatine was associated with an average weight loss of 5.5 pounds among more than half of its users.

Heart rate responses also varied widely between drugs. Nortriptyline increased heart rate by about 14 beats per minute, whereas fluvoxamine led to a reduction of approximately eight beats per minute.

Despite these variations, experts emphasized that antidepressants remain vital tools in managing mental health disorders. The study underscores the importance of personalized treatment plans, allowing physicians to choose medications that best align with each patient’s health profile.

“We do know that these medications are life-saving and life-changing, but they can vary from person to person depending on factors like metabolism, age, and other medications,” said psychiatrist Dr. Sue Varma in an interview with CBS News following the study’s release.

Dr. Varma also noted that untreated depression itself can trigger physical changes such as weight fluctuations, making it essential for both doctors and patients to weigh the benefits and risks of starting antidepressant therapy. She advised that clinicians should clearly discuss potential side effects before prescribing and monitor patients regularly for any physiological changes.

The study’s findings highlight an emerging focus in psychiatry: tailoring antidepressant use not only to mood symptoms but also to the broader physical health of patients, marking a shift toward more individualized and holistic mental health care.