Question: I am a 56 year old man who was recently prescribed a beta blocker to bring down my blood pressure. Almost right after started taking the pills I started gaining weight. I’ve put on about 10 pounds in two months. Could this weight gain be caused by the blood pressure pills or do you think it is unrelated?

Dr. Hibberd's answer: Yes, weight gain can occur as a side effect of some beta blockers, especially the older ones, such as atenolol (Tenormin) and metoprolol (Lopressor, Toprol-XL). However, the average weight gain is about 4 pounds. Newer beta blockers, such as carvedilol (Coreg), don't typically cause weight gain as a side effect. Usually, beta blockers that can cause weight gain aren't prescribed unless other medications have not worked, or unless you have a specific heart condition that requires taking those medications. The cause for weight gain is not properly understood; maybe beta blockers slow down metabolism as a whole.
If the beta blocker has been prescribed for heart failure, you need to inform your doctor immediately if this weight gain continues because it might mean that fluid is building up in your legs, abdomen or chest, indicating that that your heart failure is worsening.