Thank you for the query. I would like to your age, gender and if you can recall what anti hypertensive have you been prescribed. Taking your history into account it seems unlikely that you have been prescribed beta blocker since you heart rate is on the lower side (or it may be low as a effect of beta blocker itself). Beta blockers may cause undesirable effects of lipid profile and blood sugar. Presently, you are maintaining your BP in an acceptable range, sometimes on the lower side also. Drugs like diuretics cause increased urination and are unlikely to cause weight gain. Drugs in the calcium channel blocker group may cause some amount fluid retention and swelling in the legs, which may be a cause (however, 2.5 kgs is unlikely). I would advise you to have a salt restricted diet, as salt can cause water retention and weight gain. If possible, please monitor your water/fluid intake and urine output and get a renal function test done (urea, creatinine). In all probabilities, your weight gain may be due to fluid retention. In case you are symptomatic you should consult your cardiologist for a check up and revise of medications. Hope this helps you.