Key facts

• Lymph nodes, also known as lymph glands, are part of the lymphatic system, which fights infection.
• Most causes of swollen lymph nodes are not serious.
• The most common cause of swollen lymph nodes is a viral infection.
• Most of the time, swollen lymph nodes go away on their own without any special tests or treatment.
• Rarely, swollen lymph nodes can be caused by cancer.

What are swollen lymph nodes?

Lymph nodes, also known as lymph glands or just ‘glands’, are part of the lymphatic system, which fights infection. Lymph nodes filter impurities from the lymph, which is a type of body fluid.

Glands in many different parts of the body can become swollen, but you’re more likely to feel them in your neck, armpits or groin. You may have swollen glands in only one area of your body or in many different parts of your body at the same time.

Swollen lymph nodes are also known as lymphadenopathy.

Lymph nodes are small bean-shaped structures that are usually less than 2.5 cm in length. They are widely distributed throughout the body along the lymphatic pathways where they filter the lymph before it is returned to the blood. Lymph nodes are not present in the central nervous system. There are three superficial regions on each side of the body where lymph nodes tend to cluster. These areas are the inguinal nodes in the groin, the axillary nodes in the armpit, and the cervical nodes in the neck.

The typical lymph node is surrounded by a connective tissue capsule and divided into compartments called lymph nodules. The lymph nodules are dense masses of lymphocytes and macrophages and are separated by spaces called lymph sinuses. The afferent lymphatics enter the node at different parts of its periphery, which carry lymph into the node; entering the node on the convex side. The lymph moves through the lymph sinuses and enters an efferent lymphatic vessel, which, located at an indented region called the hilum, carries the lymph away from the node.

Common problems involving the lymphatic system can be separated into those related to:

• infection
• disease
• destruction or damage to the lymphatic system or its nodes.

Those related to infection include:

• glandular fever – symptoms include tender lymph nodes
• tonsillitis – infection of the tonsils in the throat
• Crohn’s disease – inflammatory bowel disorder.

Those related to disease include:

• Hodgkin’s disease – a type of cancer of the lymphatic system.

Those related to malformation or destruction or damage to the lymphatic system or its nodes include:

• primary lymphoedema – when the lymphatic system has not formed properly. May present as a limb or part body swelling at birth, or may develop at puberty or later in life
• secondary lymphoedema – When the lymphatic system is damaged by surgery or radiotherapy associated with the treatment of cancer, when the soft tissues are damaged by trauma, or when the lymphatic system has some other cause of structural or functional impairment.

There are many different causes of swollen lymph nodes. Most of them are not serious.

Having swollen lymph nodes usually means that your immune system is fighting an infection in the area. For example, if you have a sore throat from a virus, you may get swollen neck glands. An infection on your leg can cause swollen glands in the groin.

Causes of swollen lymph nodes include:

• viruses (such as glandular fever)
• bacterial infections (such as tonsillitis)
• some autoimmune conditions
• some medicines
• eczema
• cancer

Out of 100 people with swollen lymph nodes, only one, if any, is likely to have cancer. In young people, cancer is even less likely.

Swollen lymph nodes are also a common side effect of some COVID-19 vaccines. This usually occurs on one side only, in the armpit of the arm that was injected. It is not dangerous, and usually goes away on its own within a few weeks.

You should see your doctor urgently if you have swollen lymph nodes plus any of these symptoms:

• fever
• night sweats
• unexplained weight loss
• bruising or bleeding easily

You should also see your doctor if your lymph nodes have stayed enlarged for longer than a few weeks, have grown in size or if you have a history of cancer.

If you see your doctor about your swollen lymph nodes, they will ask you questions about your symptoms and examine you.

If you have a simple viral infection, you may not need any medical tests.

In some situations, your doctor might order blood tests or a scan such as an ultrasound. If the results suggest cancer, you may need to have a biopsy of the lymph node.

Treatment for swollen lymph nodes will depend on the cause.

Swollen lymph nodes caused by a virus don't need treatment. The glands eventually shrink back to their normal size. This may take a few weeks or longer.

If you have a bacterial infection, your doctor might give you antibiotics.

If your swollen lymph node is due to cancer, your doctor will refer you to a cancer specialist for treatment.

Sometimes, it may not be clear why your lymph nodes are swollen. If there are no worrying symptoms that suggest a serious illness, your doctor may recommend waiting a few weeks to see if your glands return to normal by themselves.