What causes a swollen foot?

Pregnancy complications, foot injuries and medication side effects are three causes of swollen feet, says WebMD. Lymphatic fluid in the tissues, a condition called lymphedema, also causes a swollen foot. Inadequate blood movement, infection, a blood clot and various diseases are other possible causes of swollen feet.

Foot swelling is typical during pregnancy, but abrupt swelling can indicate preeclampsia, says WebMD. In pregnancy scenarios when the swelling is concurrent with abdominal pain, headaches and nausea, medical attention needs to be sought as soon as possible. Hormone replacement therapy, blood pressure medications, antidepressants and diabetes medications all carry the potential side effect of swollen feet. If the swelling is severe enough, dosages or medications may need to be adjusted.