When the lymphatic impairment becomes so great that the lymph fluid exceeds the lymphatic system’s ability to transport it, an abnormal amount of protein-rich fluid collects in the tissues of the affected area. Left untreated, this stagnant, protein-rich fluid causes tissue channels to increase in size and number, reducing the availability of oxygen. This interferes with wound healing and provides a rich culture medium for bacterial growth that can result in infections: cellulitis, lymphangitis, lymphadenitis, and in severe cases, skin ulcers. It is vital for lymphedema patients to be aware of the symptoms of infection and to seek treatment at the first signs, since recurrent infections, in addition to their inherent danger, further damage the lymphatic system and set up a vicious circle.

Very rarely, in certain exceptionally severe cases, lymphedema untreated over many years can lead to a form of cancer known as Lymphangiosarcoma.

Since lymphedema is disfiguring, causes difficulties in daily living and can lead to lifestyle becoming severely limited, it may also result in psychological distress.