Sudden difficulty lifting your legs or bearing weight is not a typical symptom of flat feet or varicose veins, and it would be unusual for this to be caused solely by Aldosmin 500 mg. While medicines can occasionally contribute to weakness or other side effects, a sudden change in leg strength needs prompt medical attention because it may be related to a nerve problem, muscle disorder, spinal condition, circulation issue, or another medical problem that requires proper evaluation. The timing after starting the medicine may be coincidental, but it should still be discussed with the doctor who prescribed it. Since you are describing a significant loss of strength rather than just pain or heaviness, it is important not to ignore it or assume it will pass on its own. A neurologist would be the most appropriate specialist to assess sudden leg weakness, although an orthopaedic or vascular evaluation may also be needed depending on the findings. If the weakness is severe, worsening, affecting both legs, or accompanied by numbness, back pain, loss of balance, or bladder or bowel symptoms, seek urgent medical care as soon as possible.