What Are Lymph Nodes?
They're bean-shaped tissue areas that filter fluid (called lymph) in your body for dangerous substances and cells. They contain immune cells that remove germs, cancer cells, and damanged cells from your body.
How many lymph nodes are there in the human body?
It varies from person to person. But adults generally have about 600-800 lymph nodes. Most are spread out, but some are in groups in places such as your neck, armpits, chest, belly, and groin.
Lymph Nodes Function
Your lymph system is a key part of your immune system. It's made up of your lymph vessels and lymph nodes. Your lymph vessels connect all your lymph nodes and draw up a clear fluid called lymph from around your cells. Your lymph fluid carries waste (such as what's left of a cell after it dies) that has been removed from your cells and trapped bacteria and viruses to your lymph nodes before it flows back into your bloodstream.
The main function of your lymph nodes is to filter these foreign materials out of your lymph fluid. Lymph fluid would build up and cause swelling in your body if it weren't filtered and drained. Lymph nodes also contain immune cells (white blood cells) that help fight infections and invaders by attacking and killing them.
Bacteria and viruses have proteins on their surface called antigens. Antigens help your immune system recognize bacteria and viruses as foreign invaders so they kill them. By filtering germs out of your lymph fluid, your lymph nodes concentrate them into a space (kind of like immune system school) where your white blood cells can learn about the bacteria and viruses you have come into contact with.
The white blood cells that are in your lymph nodes include:
- Lymphocytes
- Macrophages (pronounced ma-kroh-fayjes), which surround and kill germs, recycle your dead cells, and act as helpers to your other immune system cells
- Dendritic (pronounced den-drih-tik) cells, which take the antigens from dead germs and show them to your lymphocytes so they learn to recognize them
The main white blood cells in your lymph nodes are lymphocytes, which come in two types:
B lymphocytes (B cells)
B cells have proteins on their surface that attach to antigens on the surface of the germ. Then, they make specific antibodies to those antigens. Antibodies are protein tags that attach to germs to let other white blood cells know the germs need to be killed off.
T lymphocytes (T cells)
T cells have a couple of jobs. Some are called cytotoxic (killer) T cells. These recognize and attach to antigens on the germs and kill them. Other T cells, called helper and suppressor T cells, make proteins (such as antibodies) that help other immune system cells do their job, or they tell your body to make other kinds of immune cells to help fight the infection.
Lymph Nodes Location
You have lymph nodes spread throughout your body, except in your brain and spinal cord. Some are just under your skin (superficial lymph nodes) in your neck, armpits, and groin. Others are deep in your chest and belly. Each node filters the fluid from the vessels that lead into it.
Your superficial lymph nodes drain the lymph from your head, scalp, face, arms, and legs and are located in your:
- Neck (cervical)
- Armpits (axillary)
- Groin (inguinal)
Your deep lymph nodes are in your belly and chest and they drain the lymph from around your lungs and your digestive organs. These deep lymph nodes are also called:
Mesenteric. These are lymph nodes in your mesentery, the membrane that connects your bowel to the tissue wall around your belly.
Retroperitoneal. These are lymph nodes around your kidneys and the major blood vessels that connect your lower body to your heart.
Mediastinal. These are lymph nodes around your trachea (windpipe), esophagus, heart, lungs, and large blood vessels that lead to your heart. Some of these are supraclavicular, which means they are above your collarbones. These overlap with some of the superficial cervical lymph nodes.
Soft and Hard Lymph Nodes
Swollen lymph nodes are generally soft, or spongy. They're bigger than normal (which is about as big as a couple of peas together or a bean). They may feel like they slip or move around under your skin. They may also feel tender or painful when you press on them or move that area. For instance, a swollen lymph node under your jaw might hurt when you chew food.
If your lymph nodes feel hard, don't move around under your skin, and get big very fast, it can be a sign of cancer. If this is the case, go see your doctor right away.
Swollen Lymph Nodes
Your lymph nodes usually swell because your body is fighting off an infection. It's a sign that more lymphocytes are in action than usual, trying to kill off germs.
You may notice swelling most often in the nodes in your neck and under your chin. When you have got a cold or the flu and go see your doctor, they often feel around your neck and under your jawbone to check if those nodes are swollen or tender. Infections in your upper respiratory system often cause the lymph nodes in your neck to swell.
Sometimes, medicines such as phenytoin (taken for seizures) or drugs that prevent malaria can cause swollen lymph nodes.
Most common causes
These include:
- Common cold
- Flu
- Sinus infections or sinusitis
- Minor skin infections
- Strep or staph infections
How to check for swollen lymph nodes
To check for swollen lymph nodes, use your fingertips in a gentle, circular motion to feel for lumps and tender areas under your skin on both sides of your body. Check your neck, in front of and behind your ears, above your collarbones, all around your armpits, and around your groin.
Red Flags
Most swollen lymph nodes are harmless and clear up on their own. But see your doctor if:
- Your nodes have been swollen for more than two to four weeks
- Your nodes keep getting bigger or don't shrink at all
- Your nodes feel hard, rubbery, or fixed in place (not moving when you push on them)
- Your nodes are larger than about 1 cm (roughly the size of a pea or bigger), especially if they're growing
- Your nodes appeared without any obvious infection or illness
- You have swelling in the area just above your collarbone, which is more concerning than nodes in the neck or under the jaw
Also get checked if swelling comes with:
- A fever lasting more than a few days or drenching night sweats
- Unexplained weight loss
- Persistent fatigue
- Swollen nodes in many areas of the body at once
- A new medication, which can occasionally cause it
Go to urgent care or the ER if:
- You have trouble breathing or swallowing
- The area is red, hot, very painful, and swelling quickly (possible abscess or serious infection)
- You have a high fever with a stiff neck
Takeaways
Your lymph nodes are an important part of your immune system. They filter materials out of your lymph fluid to help keep you healthy. Talk to your doctor if you notice swollen or tender lymph nodes because this could be a sign of an illness or an infection. Most causes of swollen lymph nodes are minor, but get emergency care if you have trouble breathing, a high fever, or the swollen node area is hot and painful. When in doubt, see a doctor.
FAQs: Lymph Nodes
How long do lymph nodes stay swollen after an infection?
Usually, two to four weeks. But minor residual swelling may last for many weeks.
Can you remove lymph nodes, and what happens if you do?
Yes, a surgeon can remove lymph nodes through a procedure called a lymphadenectomy. It's an important part of cancer staging and treatment and can keep cancer from spreading. Risks include nerve damage and blood clots.
How do doctors treat swollen lymph nodes?
They treat swollen lymph nodes by finding and treating the underlying cause.
What tests do doctors use to evaluate a suspicious lymph node?
They usually use a combination of physical exam, blood tests, imaging studies, and tissue biopsy.