Weakness and leg weakness after a cold may be caused by the cold itself, or there may be other reasons, such as a lack of potassium or medication side effects. 1. Colds: Colds are caused by viral infections, and the clinical symptoms are usually coughing, runny nose, sneezing, loss of appetite, and poor spirits. If the above symptoms are more serious, the phenomenon of weak legs may occur. 2. Potassium deficiency: when the human body is deficient in potassium, there will be muscle weakness, edema, and in severe cases, weakness and weakness. 3. Side effects of medicines: If patients with high blood pressure suffer from a cold and take antihypertensive medicines such as metoprolol, they will suffer from fatigue and weakness. If you have a cold, you can go to the hospital for a detailed examination to determine the specific cause of the disease, and then use the appropriate method of treatment under the guidance of a professional doctor, to avoid the blind use of drugs.