Swelling on the left side of the foot, need to be carefully analyzed: 1, if this swelling is caused after trauma, then it is the swelling caused by trauma, often with a history of trauma, do the appropriate examination can be differential diagnosis. This kind of trauma may cause pain without swelling, so that it is best to do X-ray to identify; 2, in addition to trauma, it may be mosquito bites, mosquito bites caused by swelling, redness, itching is its characteristics; 3, if you exclude the above, it may be inflammation. Swelling in the foot, may be cellulitis, redness, swelling, heat, pain, is the clinical manifestations of cellulitis, in the appearance can be clearly judged; 4, if the patient’s uric acid is elevated, there can be swelling caused by gouty nodules, this kind of swelling in the administration of small sodas, painkillers or hormones, can be obvious pain or swelling; 5, excluded from the above situation, it is necessary to consider whether it is unilateral The unilateral limb blood reflux is not good. Unilateral limb blood return is not good easy to form blood clots, resulting in unilateral limb swelling, this swelling need to do ultrasound to confirm the existence of thrombosis.