When a patient has a cold, it may cause a decrease in platelets. Some patients may have a decrease in platelets because of the decrease in immune function after a cold, but the platelets will gradually return to normal after the recovery of cold symptoms. It may also be caused by diseases such as thrombocytopenic purpura, aplastic anemia, etc. Therefore, when a patient has a reduced platelet count during a cold, the platelet count should be reviewed in time after the patient has fully recovered from the cold. If the platelets are not completely back to normal, further examination is needed to rule out whether the patient is suffering from blood-related diseases.