A swollen lymph node is a small, bean-shaped gland that has enlarged beyond its normal size, typically in response to an infection, injury, or immune reaction happening nearby. Nodes are generally considered swollen when they exceed about 1 centimeter in diameter, though groin nodes can be up to 1.5 centimeters and still be normal. Most of the time, swollen lymph nodes signal that your immune system is doing exactly what it’s supposed to do.
What Lymph Nodes Actually Do
Lymph nodes act like security checkpoints throughout your body. Fluid called lymph, which leaks out of your blood vessels carrying proteins, nutrients, and stray cells, passes through these nodes before cycling back into your bloodstream. Inside each node, immune cells scan that fluid for anything that doesn’t belong: viruses, bacteria, fungi, damaged cells, even cancerous cells. When they find a threat, they either destroy it directly or flag it so other immune cells can respond.
When your lymph nodes detect a problem, they ramp up production of immune cells. That surge of activity is what causes the swelling. The node fills with more white blood cells, more fluid, and sometimes the debris of destroyed invaders. It’s essentially your immune system working overtime in one concentrated spot.
Where You’re Most Likely to Feel Them
You have hundreds of lymph nodes scattered throughout your body, but most are too deep to feel. The three areas where nodes cluster close to the skin’s surface are your neck, your armpits, and your groin. These are the spots where you’ll notice swelling first.
Which nodes swell often points to the source of the problem. Swollen neck nodes usually relate to an upper respiratory infection, a sore throat, or a dental issue. Armpit nodes may react to an infection in the arm or hand, or sometimes to a breast-related concern. Groin nodes tend to respond to infections or injuries in the legs, feet, or genital area. When nodes swell in multiple areas at once, it more often suggests a body-wide infection or a systemic condition rather than something localized.
The Most Common Causes
Infections cause the vast majority of swollen lymph nodes. Upper respiratory infections, strep throat, ear infections, skin wounds, and dental abscesses are everyday triggers. Viral illnesses like mononucleosis, the flu, and the common cold are frequent culprits, especially for neck swelling. Bacterial infections from organisms like Streptococcus and Staphylococcus are also common, particularly when there’s a skin infection or open wound nearby.
Beyond infections, several other conditions can cause lymph node swelling:
- Autoimmune diseases. Conditions like lupus, rheumatoid arthritis, and Still’s disease can cause chronic or recurring swelling because the immune system stays persistently activated.
- Medications. Certain drugs, including some seizure medications, can trigger lymph node enlargement as a side effect.
- Cancers. Lymphomas originate in the lymph nodes themselves, while other cancers can spread to nearby nodes. This is less common than infectious causes but is the reason persistent swelling deserves attention.
What a Swollen Node Feels Like
When lymph nodes swell from a common infection, they typically feel soft, tender, and slightly painful to the touch. Some people notice the soreness even without pressing on the area. The nodes move freely under the skin when you push on them, sliding back and forth like a small marble beneath the surface. They might range from the size of a pea to the size of a grape, and the overlying skin can feel warm.
The texture and behavior of a swollen node carries meaning. Nodes that feel rubbery may indicate an abscess forming or significant inflammation. The characteristics that raise more concern are firmness, lack of pain, and being “fixed,” meaning the node doesn’t shift when you press it. Nodes that are hard, painless, and seem anchored in place have a higher chance of being associated with something more serious, though even these findings don’t automatically mean cancer.
How Long Swelling Typically Lasts
With a routine infection, lymph node swelling usually peaks within a few days and then gradually subsides over two to four weeks as the infection clears. Sometimes the nodes shrink faster than that, especially if you’re taking antibiotics for a bacterial infection. It’s also normal for nodes to stay slightly enlarged for a few weeks after you feel better, since the immune response winds down gradually.
Swelling that hasn’t improved after four weeks, or that keeps growing, falls into a different category. The same is true for nodes that appear without any obvious infection, nodes larger than 2 centimeters, or swelling accompanied by unexplained weight loss, night sweats, or persistent fevers. These patterns don’t necessarily mean something is wrong, but they do warrant a closer look.
How Doctors Evaluate Persistent Swelling
A physical exam is the starting point. Your doctor will feel the swollen nodes, noting their size, texture, mobility, and whether they’re tender. They’ll also check for swelling in other areas you might not have noticed and look for signs of infection that could explain the reaction.
If the cause isn’t obvious, the next step is usually blood work to check for signs of infection, inflammation, or immune system abnormalities. Imaging such as a chest X-ray, CT scan, or ultrasound can reveal infections or masses that aren’t visible from the outside. For breast-related concerns, a mammogram may be part of the workup.
When swelling persists and other tests haven’t provided a clear answer, a biopsy may be recommended. This involves removing a sample from the node, or sometimes the entire node, and sending it to a lab for closer examination. A biopsy gives the most definitive information about what’s happening inside the tissue.
Infection-Related Swelling vs. Something More Serious
The key differences come down to a few physical characteristics. Infection-related nodes tend to be painful, soft, and movable. They usually appear quickly, correspond to an obvious illness, and shrink within a few weeks. Nodes associated with cancer tend to be painless, firm or hard, and fixed in place. They grow gradually over weeks and don’t respond to antibiotics or resolve on their own. On imaging, concerning nodes tend to be rounder and lack the normal internal structure visible in healthy or reactive nodes.
Context matters too. A tender, swollen node under your jaw during a cold is almost certainly your immune system responding normally. A painless, hard node in your neck that’s been growing for six weeks without any infection is a different scenario entirely. Age plays a role as well: in children and young adults, swollen lymph nodes are overwhelmingly caused by infections. In adults over 40, persistent unexplained swelling is evaluated more carefully.
What You Can Do at Home
For garden-variety swelling caused by a cold or minor infection, there’s no specific treatment needed for the nodes themselves. They’ll return to normal once the underlying infection resolves. A warm compress applied to the swollen area can ease discomfort. Over-the-counter pain relievers can help with tenderness. Staying hydrated and resting supports your immune system in clearing the infection faster.
If the swelling is caused by a bacterial infection, antibiotics prescribed for the infection will also address the lymph node enlargement. Left untreated, some bacterial infections can lead to abscess formation within the node itself, which may need drainage. This is one reason it’s worth getting evaluated if swelling is worsening, the skin over the node becomes red and hot, or you develop a fever.