Medication-Induced Weight Gain
Weight gain caused by common prescription drugs — some antidepressants, steroids, antipsychotics and more — often manageable by switching to weight-neutral alternatives.
Plain English
Patient-Friendly Explanation
Many common prescription medicines can cause weight gain as a side effect, including some antidepressants, antipsychotics, steroids, epilepsy medicines, blood pressure tablets and insulin. The gain usually happens through increased appetite, fluid retention or a slower metabolism. If a medicine is affecting your weight, talk to your doctor — there are often equally effective options with fewer metabolic side effects.
Medical
Clinical Definition
Medication-induced weight gain is a common, under-recognised barrier to weight management. High-risk classes include atypical antipsychotics such as olanzapine and clozapine (frequently 4-10 kg in the first year), certain antidepressants (mirtazapine, paroxetine, amitriptyline), glucocorticoids, sulfonylureas and insulin, some beta-blockers (atenolol, metoprolol) and antiepileptics (valproate, gabapentin, pregabalin). Mechanisms include histamine H1 and serotonin 5-HT2C receptor antagonism, increased appetite and fluid retention, reduced resting energy expenditure and altered adipocyte metabolism. Management is structured: confirm the temporal association, switch to weight-neutral alternatives where clinically appropriate (for example bupropion or fluoxetine for depression, ACE inhibitors or angiotensin-receptor blockers for hypertension, metformin or SGLT2 inhibitors where indicated in diabetes), and never discontinue psychiatric or corticosteroid medication abruptly without specialist review.
Key Insight
Why It Matters
If you have been gaining weight and take regular medication, the prescription bottle may hold part of the answer. Dr Joseph Wang reviews every patient's full medication list to find weight-friendlier options where it is safe to switch.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: September 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
