Weakness of legs even after the flu is almost over may be caused by potassium deficiency, calcium deficiency and insufficient food intake, which can be improved by taking oral medication. 1. Potassium deficiency: Potassium deficiency is mainly caused by insufficient intake of potassium in the body, which will lead to muscle weakness, abdominal distension and body weakness, and also cause leg weakness even after the cold is almost over, you can follow the doctor’s instructions to take potassium chloride extended-release tablets, potassium citrate granules and other medications to treat it. 2. Calcium deficiency: Calcium deficiency is usually caused by excessive consumption of calcium and insufficient exposure to sunlight, which will result in muscle weakness, and can be treated with calcium gluconate oral solution and calcium carbonate granules under the guidance of a doctor. 3. Insufficient food: Insufficient food may be the result of eating less nutritious food during the cold, which will lead to muscle cramps and leg weakness, you can eat more nutritious food to regulate, do not need special medication. If your legs are still weak after a cold or flu, it is possible that your body’s resistance is lowered and your joints are damaged, so you need to go to the hospital in time to do a comprehensive examination and get a clear picture of the cause of the problem.