Foot sprain refers to ankle sprain, sprain for six months has not been swelling, the common causes are premature exercise, too heavy injury, poor blood circulation, etc., the treatment includes rest, internal fixation, surgery and drug therapy. 1. Premature exercise: no sufficient rest after ankle sprain, premature weight-bearing exercise or long-time standing work may lead to swelling or even aggravation, should be appropriate to elevate the lower limbs to promote swelling and reduce the activities, adequate rest, is conducive to swelling. 2. Excessive injury: because of sprains, ligament, tendon injuries or fractures, because of ligament, tendon, fracture recovery time is longer, there may be swelling does not go down. You can take non-steroidal anti-inflammatory drugs orally, such as diclofenac sodium extended-release tablets, and carry out external fixation of the lower limb plaster, and surgery is needed for serious cases. 3. Poor blood circulation: because of diabetes, hyperlipidemia and other reasons lead to lower extremity vascular occlusion, venous return obstruction, can also lead to swelling is difficult to subside, you can use to improve blood circulation of drugs, such as thrombolytic injection and so on. The causes of foot sprains six months after the swelling does not go down more reasons, may also be related to gout, tumors and other diseases, it is recommended to consult a doctor in a timely manner, to clarify the cause of the disease, targeted treatment.