Thrombosis is the pathological development of blood clots. Both therapies had an association with venous clots and pulmonary embolism. Patients with polycythemia vera are prone to the development of blood clots (thrombosis). Thrombolysis therapy uses thrombolytic drugs that dissolve blood clots. Side effects include blood clots and infection.. Blood from a ruptured cerebral aneurysm clots around a cerebral artery, releasing thrombin. Severe side effects may include blood clots and stroke. Serious side effects may include toxic epidermal necrolysis, rhabdomyolysis, gallstones, blood clots, and pancreatitis. Severe side effects include tumor lysis syndrome, blood clots, and peripheral neuropathy. Coagulation can physically trap invading microbes in blood clots. Complications of sclerotherapy are rare but can include blood clots and ulceration. Thromboxanes are responsible for the aggregation of platelets that form blood clots. Plasmin is a serine protease that acts to dissolve fibrin blood clots. There is a high risk that thalidomide can cause excessive blood clots. Thrombolysis is enzymatic destruction of blood clots.