My son just showed me this painful lump on the side of his neck. It appeared overnight and he is really scared. The pediatrician is closed for the wee. Full article

Why Neck Lumps in Children Can Appear Suddenly

The neck contains many important structures, including:

Because children’s immune systems are constantly responding to viruses, bacteria, and environmental exposure, swollen lymph nodes are especially common.

In many cases, a lump that appears quickly is related to the body fighting off an infection.

However, not every lump is the same. Size, pain, redness, fever, and other symptoms all matter when evaluating the situation.

The Most Common Cause: Swollen Lymph Nodes
One of the most common explanations for a painful lump on the side of a child’s neck is an enlarged lymph node.

Lymph nodes are small glands that help the immune system fight infection. Children have many lymph nodes in the neck area, and they can swell when the body reacts to:

Colds
Ear infections
Throat infections
Viral illnesses
Dental problems
Minor skin infections
Sometimes the child may not even seem very sick otherwise.

What Swollen Lymph Nodes Usually Feel Like

A swollen lymph node may:

Feel round or oval
Move slightly under the skin
Be tender or painful
Appear suddenly
Affect one side of the neck more than the other
The size can vary from pea-sized to significantly larger.

Mild swelling during or after illness is common in children.

Common Illnesses That Can Cause Neck Swelling

1. Viral Infections
Viruses are one of the most common reasons lymph nodes enlarge.

Examples include:

Common cold
Flu
Adenovirus
Mononucleosis
COVID-19
Other childhood viruses
With viral infections, the child may also have:

Runny nose
Fatigue
Fever
Sore throat
Cough
2. Strep Throat or Tonsillitis
Bacterial throat infections can cause painful swollen nodes, often along the jawline or side of the neck.

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Symptoms may include:

Fever
Pain swallowing
Red throat
White patches on tonsils
3. Ear Infections
Children with ear infections may develop enlarged lymph nodes nearby.

Signs may include:

Ear pain
Fussiness
Trouble sleeping
Fever
4. Dental Problems
Tooth infections or gum irritation can sometimes cause swelling in nearby lymph nodes.

Other Possible Causes of Neck Lumps
Although swollen lymph nodes are common, other causes exist as well.

Salivary Gland Swelling
Salivary glands can become inflamed due to: