Would 200mg of testosterone at 31 cause heart disease and other deadly problems if used just once for 3-6 months if you never did it again after?

Testosterone undecanoate can cause blood pressure (BP) increases that can increase the risk of major adverse cardiovascular events (MACE), including non-fatal myocardial infarction, non-fatal stroke, deep vein thrombosis and cardiovascular death. These can occur in anyone at any time, but are more common in persons who already suffer from high blood pressure and other heart conditions.

Time will tell and everyone is different. I would go to drugs.com and read all about them and any other drugs you are taking. What is your family history of early heart disease. Are yo lipids normal? If you smoke stop. and keep your BMI below 25 and SysBP under120 to reduce your risk. Remember heart disease is not a natural problem in humans. It only occurs when you feed your genome wrong.