The most common causes of swollen glands include: 1  Bacterial infection, such as a sore throat. 2  Mouth sores or tooth infection. 3  Viral infection, such as glandular fever. 4  Skin infection.5  Ear infection.6  Sexually transmitted infection (STI).ow swollen glands are treated depends on what's causing them. To relieve the discomfort of swollen glands and the illnesses that cause them, the following home care methods may help: 1  Over-the-counter pain relievers, such as paracetamol or a nonsteroidal anti-inflammatory drug (NSAID) like ibuprofen.