Hello. Swelling of the leg could be due to various causes and each of them have to be excluded. DVT may be commonly noticed in non-ambulant individuals, post surgery, pregnancy, post delivery, chronically ill patients, etc. Sometimes, a DVT can be spontaneous too. Anti-coagulants are given to stabilize the clot and prevent it from migrating to the lungs and prevent the chances of a PE (pulmonary embolism). However, if a DVT is suspected, a detailed evaluation would be needed along with continuing the medications. Other vascular conditions like varicose veins, chronic venous insufficiency can also cause swelling. Swelling due to DVT is usually sudden with severe, unbearable leg pain, with or without redness, inability to walk, etc. Sometimes, infection of the skin over the legs due to varicose veins can also present with such symptoms. If there is any breathlessness, increase in swelling or redness he would need hospitalisation in the ICU. A color doppler study of the venous system and a CT venogram or D-dimer would be helpful in diagnosing DVT. In case of cellulitis, Intravenous antibiotic injections would be needed. Other routine blood tests like complete blood picture, renal and liver function tests, PT/APTT, INR would be needed.