Lymphedema in leg - how long does it last?

True lymphedema is. Typically a permanent condition that requires daily control with compression therapy. Many times swelling or edema is called lymphedema when it is not truly the case. See a lymphedema specialist if diagnosis is not certain.
Lymphedema. Lymphedema of the leg may be a reaction to an underlying foot issue such as infection, or it may be failure of your lymph channels to remove fluid from the lower extremity. It is unclear how long this will last, and I would recommend evaluation to determine why he would have the lymphedema. Use of support/compression stockings would be of great benefit to help with the situation.
Weeks to years. Lymphedema may improve substantially with great physical therapy. Find a lymphedema physical therapist and use compression. With luck it will resolve but some cases are persistent.