There are a number of causes of swollen lymph glands. The most common cause is infection. See your doctor if you have swollen lymph glands and you do not know why they have swollen, or if swollen lymph glands caused by an infection do not go down again within two weeks.Small lymph glands (sometimes called lymph nodes) occur throughout the body.he most common cause is infection. See your doctor if you have swollen lymph glands and you do not know why they have swollen, or if swollen lymph glands caused by an infection do not go down again within two weeks.