Can Allergies Cause Swollen Lymph Nodes?

Allergies occur when your immune system overreacts to allergens like pet dander, pollen, mold, certain foods, or medications.

Allergy symptoms may include a runny nose, congestion, coughing, wheezing, itching, and sometimes, swollen lymph nodes.

Lymph nodes are small, bean-shaped organs that help remove harmful substances from your body. Knowing the cause of swollen lymph nodes is important for treating them.

It’s possible for allergies to cause swollen nodes. 

Your lymph nodes filter harmful substances from your body and help fight infections. Allergens can trigger your immune system to release inflammatory chemicals to fight off the perceived threat. This causes inflammation (swelling) in the sinuses, nasal passages, and airways. This inflammation can also affect your lymph nodes, causing them to become larger or tender. 

In some cases, swollen lymph nodes may indicate sinusitis (a sinus infection). People with allergies are three times more likely to get sinusitis than those without. Allergy-related inflammation and mucus buildup in the sinuses create an ideal environment for bacteria to grow, raising the risk of sinusitis. Since your lymph nodes are part of your immune system, they may swell as your body fights the infection.

Lymph nodes are part of the lymphatic system, which helps maintain the fluid in your body and is an important part of the immune system. Your body has approximately 800 lymph nodes, with groups in the neck, armpits, chest, abdomen, and groin. 

Lymph nodes filter lymph fluid, which carries immune cells, waste products, and other substances throughout the body. They filter and remove bacteria, viruses, and abnormal (cancer) cells. Lymph nodes store and make immune cells, such as lymphocytes (white blood cells), that help the body fight infections.

When your body fights an infection or reacts to an allergen, lymph nodes can become swollen as they filter out the harmful substances to protect your body from the threat.

When allergies cause swollen lymph nodes, you’ll typically notice a pea-sized (1-2 centimeter) tender lump under your skin, usually in your neck, behind your ears, or under your jaw or chin. Allergy-related lymph node swelling occurs with classic allergy symptoms, such as congestion, sneezing, watery eyes, runny nose, itchiness, or a skin rash.

Many other conditions can cause swollen lymph nodes, so knowing the difference between allergies and other possible causes is important. If you have seasonal allergies, you may notice swollen lymph nodes when pollen counts are high. If you’ve had recent exposure to a food allergen or pet dander, you may have an allergic reaction that causes swollen lymph nodes.

Healthcare providers diagnose the cause of swollen lymph nodes by performing a physical exam, reviewing your medical history, and running diagnostic tests. They’ll ask about your allergy history, recent exposures to allergens, and other symptoms you’re experiencing.

Blood tests can measure eosinophil counts (white blood cells associated with allergies), and immunoglobulin E (IgE) antibody levels can help determine if allergies are causing swollen lymph nodes. IgE antibodies cause your body’s allergic response.

To rule out more serious conditions, your healthcare provider may recommend allergy testing, imaging scans, or a lymph node biopsy. A lymph node biopsy is a procedure where a healthcare provider removes a small part of your lymph node to examine for any abnormalities.

When your lymph nodes swell from allergies, the most effective approach is to treat the underlying allergic reaction.

Over-the-counter (OTC) and prescription medications, such as antihistamines like Claritin (loratadine), decongestants like Allegra-D (fexofenadine), and nasal corticosteroid sprays like Flonase (fluticasone propionate), can help reduce swelling and treat allergy symptoms. 

Several home remedies can also help reduce lymph node swelling and ease discomfort, such as: 

• Apply a warm compress: Soaking a cloth in warm water and gently holding it against your swollen lymph nodes can help relieve pain and promote lymphatic drainage.
• Stay hydrated: Drinking plenty of water can help keep lymph fluid flowing throughout the body. 
• Get good sleep: Good-quality sleep keeps your immune system strong and protects against or helps you recover from allergy-related sinus infections.
• Take OTC medicines: Advil (ibuprofen) and Tylenol (acetaminophen) may reduce pain and tenderness associated with swollen lymph nodes.

Swollen lymph nodes from allergies should return to their normal size within a couple of weeks.

Seek medical attention if your swollen lymph nodes: 

• Last for more than two weeks despite allergy treatment 
• Are painful
• Appear without any classic allergy symptoms
• Continue to grow larger
• Feel hard, fixed, or immovable under the skin 

It’s also important to see a healthcare provider if swollen lymph nodes occur alongside other symptoms, such as:

Allergies can cause swollen lymph nodes as part of the immune system’s response to allergens.

If allergies are causing swollen lymph nodes, you’ll typically experience classic allergy symptoms at the same time.

See a healthcare provider if lymph node swelling persists, is painful, or occurs with symptoms like fever or unexplained weight loss.