What Are Lymph Nodes, and Why Do They Swell?

Lymph nodes are small, bean-shaped glands that are part of your body’s immune system. They help filter harmful substances and fight infection. They’re located in groups throughout the body—especially in the neck, underarms, groin, and behind the ears.

Swelling is often a sign of your immune system responding to something. But when that swelling becomes persistent, grows over time, or is accompanied by other symptoms, it may be worth speaking to a medical professional.

1. A Lump That Doesn't Go Away

Most swollen lymph nodes due to infection will shrink within a few weeks. But if the lump has been present for more than two to three weeks, feels hard, and doesn’t move easily under the skin, it could be cause for further investigation.

Look for:

A lump larger than a marble

No tenderness or pain

Growth over time instead of shrinking

2. Swelling in Multiple Areas

Localized swelling is often due to a nearby infection. But multiple enlarged lymph nodes in different areas (neck, underarms, groin) may point to a systemic condition, especially if not related to an obvious illness like the flu or mono.

Keep an eye on:

Symmetry (nodes on both sides swollen)

Swelling with no known cause

Duration beyond 3–4 weeks

3. Unexplained Night Sweats

Persistent night sweats that drench your sheets or pajamas—especially when not linked to temperature, stress, or menopause—may be a systemic sign of something more serious.

It's a good idea to track:

Frequency (more than twice a week)

Accompanying fatigue or fever

Weight changes occurring at the same time

4. Unexplained Weight Loss

Losing weight unintentionally—without changes in diet, exercise, or routine—can sometimes be an indicator of metabolic or immune-related changes.

Medical professionals often consider a loss of 10% of body weight or more over 6 months without explanation to be a reason to investigate further, especially if paired with other symptoms like fatigue or swollen nodes.

5. Fever That Won’t Go Away

An occasional mild fever is common with infection. But if you're experiencing low-grade fevers for weeks without an obvious cause, or recurring fevers at night, this may point to an ongoing issue.

This is especially relevant when fever is accompanied by:

Fatigue

Night sweats

Swollen nodes that remain unchanged

6. Itching or Rashes Without a Clear Cause

In certain cases, blood-related cancers like lymphoma can trigger persistent itching, especially in the lower legs or arms. This may occur with no rash, or with very mild skin irritation that doesn’t improve.

This symptom can be easy to dismiss as dryness, allergies, or environment—but if it's chronic, unexplained, and resistant to treatment, it may be worth flagging during an exam.

7. Shortness of Breath or Chest Discomfort

In rare cases, enlarged lymph nodes in the chest (called mediastinal lymphadenopathy) may press on nearby airways or blood vessels, causing shortness of breath or a tight feeling in the chest.

This symptom doesn’t always occur with pain but may be accompanied by:

Fatigue during mild activity

A dry, persistent cough

Discomfort when lying down flat

When to Talk to a Professional

The presence of one or two symptoms alone doesn’t confirm anything serious. But multiple signs occurring at the same time, especially if they last more than a few weeks, should be discussed with a healthcare provider.

Common scenarios to act on:

A lump that feels hard, fixed, and doesn’t go away

Swelling in more than one region of the body

B symptoms (fever, night sweats, weight loss)

An early conversation with your doctor can lead to either peace of mind—or early detection of something that deserves more attention.

What Could Cause Similar Symptoms?

Many conditions can cause swollen lymph nodes and related signs. These include:

Viral infections (like mononucleosis)

Autoimmune diseases (like lupus)

Skin infections or dental abscesses

Reactions to medications

Importance of Early Detection

That’s why it’s important to avoid self-diagnosis and seek guidance from a licensed healthcare professional when symptoms persist or worsen. Lymph nodes are like a checkpoint system for your immune health. While swelling is often harmless, it can also be an important signal. Learning the potential warning signs can empower you to take timely action—not in fear, but with informed awareness.

Early observation, consistency in tracking symptoms, and regular communication with your doctor are the best steps forward if you notice something unusual. Most people don’t give much thought to their lymph nodes—until one of them swells up. Usually, it’s nothing serious. A minor infection, allergies, or even stress can cause temporary lymph node swelling. But in some cases, a swollen lymph node can be a sign of something more serious, including lymphoma or other forms of cancer. The tricky part? The symptoms can often be subtle. If you’ve noticed changes in your body that persist, understanding the possible early warning signs can help you make informed decisions about your health.