Many people have problems with insufficient flow via the lymphatic vessels resulting in oedema at the ankles/lower legs and other parts of the body, for various reasons.
To maintain the flow of lymphatic fluid there has to be sufficient muscle action to compress the lymph vessels and force the lymph toward the subclavian veins.
Make sure that you walk or engage in some sort of exercise on a daily basis. Swimming, in particular helps the problem greatly, regardless of where the lymphatic fluid is accumulating
If it is the ankles that are swelling as is often the case, elevating the ankle and rotating it can help stubborn lymphatic fluids to drain.
Be sure to drink adequate water. Often our water intake in far too low, especially in warm weather, to allow the body to drain and detoxify adequately.
Also a good lymphatic massage can work wonders, especially if done regularly, as a complete lymphatic massage systematically opens up the lymphatic ducts and encourages drainage.
If these measures do not help then you should consider the state of the bowel, especially if it is the left ankle that is swelling, as a distended lower bowel can hinder the flow of lymph back up the body and incidentally can also hinder venous flow.
See pages on ‘ Bowel -improving action’ and ‘ Bowel motions-what’s normal!’.
Echinacea is a herb that can be specific for helping lymphatic action.
Also consider having an Osteopathic examination to ensure that there is no restriction in the bony articulations of the ankle or lower back or hip that could impede lymphatic flow