Platelets below 6×10⁹/L are very dangerous, the patient’s condition is critical, the risk of spontaneous bleeding is high and life-threatening, and immediate emergency care or hospitalization for platelet-boosting therapy is recommended. The severity of thrombocytopenia can be graded according to the number of platelets, and it is generally accepted that platelet values of 10×10⁹/L or less are associated with the possibility of spontaneous internal hemorrhage, or even hemorrhage of vital organs as well as lethal intracranial hemorrhage. Urgent platelet transfusion, absolute bed rest, and treatment with a combination of platelet-raising drugs (recombinant TPO and IL-11) are required until platelets rise to a safe level or 50 × 10⁹/L higher than before treatment. In conclusion, platelets below 6 × 10⁹/L are serious and complex and require individualized treatment, a combination of various therapies, etiologic therapy, and platelet elevation to the safe range as soon as possible. Drugs should be used under the direction of a physician.