There is a risk of thrombosis when patients with congenital deficiency are treated with human fibrinogen, particularly with high dose or repeated dosing. Patients given human fibrinogen should be observed closely for signs or symptoms of thrombosis. In patients with a history of coronary heart disease or myocardial infarction, in patients with liver disease, in peri- or post-operative patients, in neonates, or in patients at risk of thromboembolic events or disseminated intravascular coagulation, the potential benefit of treatment with human plasma fibrinogen should be weighed against the risk of thromboembolic complications. Caution and close monitoring should also be performed. If allergic or anaphylactic-type reactions occur, the injection/ infusion should be stopped immediately. In case of anaphylactic shock, standard medical treatment for shock should be implemented. In the case of replacement therapy with coagulation factors in other congenital deficiencies, antibody reactions have been observed, but there is currently no data with fibrinogen.