Does omeprazole cause swollen lymph nodes? Understanding Rare but Serious Side Effects

October 12, 2025 •

4 min read

While swollen lymph nodes are not a common side effect of omeprazole, they are a potential sign of a rare but serious adverse drug reaction. This can be part of a severe allergic response known as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS). It is crucial for patients to understand this connection and know when to seek emergency medical attention.

Quick Summary

Swollen lymph nodes, or lymphadenopathy, can occur as a symptom of a severe, though rare, allergic reaction to omeprazole. This can indicate Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) or other hypersensitivity reactions. Immediate medical consultation is essential.

Key Points

Rare but Serious Side Effect: Swollen lymph nodes (lymphadenopathy) are not a common side effect of omeprazole but can be a sign of a severe, systemic reaction.
Linked to DRESS Syndrome: Lymphadenopathy is a key feature of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), a rare but potentially fatal hypersensitivity reaction to omeprazole.
Accompanied by Other Symptoms: If omeprazole causes swollen lymph nodes, it is often part of a larger reaction involving fever, a widespread rash, and potentially organ damage.
Immediate Medical Attention Required: If you develop swollen lymph nodes while taking omeprazole, seek medical help immediately, especially if accompanied by other systemic symptoms.
Management Involves Discontinuation: Treating drug-induced lymphadenopathy requires discontinuing the medication under a doctor's supervision.
Distinct from Common Causes: This type of lymphadenopathy is a systemic immune response, different from the localized swelling caused by common infections.
Not a Common Allergic Reaction: While anaphylaxis is a known allergic reaction, DRESS and other hypersensitivity reactions are delayed-onset and more complex.

Is There a Connection Between Omeprazole and Swollen Lymph Nodes?

For most people who take omeprazole (Prilosec), a proton pump inhibitor (PPI) used to treat acid-related gastrointestinal issues, side effects are typically mild, such as headaches, abdominal pain, or nausea. However, the appearance of swollen lymph nodes, medically known as lymphadenopathy, is an infrequent and serious sign that should not be ignored. It is associated with more severe, systemic drug reactions rather than being a standalone side effect.

The relationship between omeprazole and swollen lymph nodes is linked to severe hypersensitivity syndromes, specifically Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS). This is a potentially life-threatening condition that involves a complex immune response triggered by the medication. The lymphadenopathy seen in DRESS syndrome is a key clinical feature, reflecting a widespread inflammatory process as the immune system reacts negatively to the drug.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)

DRESS syndrome is a delayed-onset drug reaction that can appear weeks to months after starting a new medication. In addition to swollen lymph nodes, the syndrome is characterized by a triad of severe symptoms:

Fever: Often high-grade and persistent.
Rash: A widespread, erythematous (red) rash that can be macular, papular, or progress to blistering.
Systemic Involvement: This includes internal organ damage, such as hepatitis (liver), nephritis (kidneys), pneumonitis (lungs), or myocarditis (heart).
Blood Abnormalities: Eosinophilia (an increase in eosinophils, a type of white blood cell) is a common finding.

If omeprazole is the suspected cause, it must be discontinued immediately under the supervision of a healthcare provider. The syndrome's symptoms can persist for weeks even after stopping the drug and may require hospitalization and treatment with corticosteroids or other immunosuppressants.

The Role of the Lymphatic System in Drug Reactions

The lymphatic system is a vital part of the immune system, and lymph nodes act as filters, trapping and destroying pathogens and foreign substances. In a drug hypersensitivity reaction, the body's immune cells mistake the medication or its metabolites as a threat. T-cells are activated, leading to a cascade of inflammation. The lymph nodes become swollen as they swell with these activated immune cells, working to clear what they perceive as an invading substance.

This is distinct from the more common causes of swollen lymph nodes, such as a localized infection (like a cold or strep throat), where only the nodes near the infection site might swell. In a systemic reaction like DRESS, the lymphadenopathy can be more widespread, occurring in the neck, armpits, and groin.

Other Severe Skin Reactions with Lymphadenopathy

Beyond DRESS, other severe skin reactions are associated with omeprazole and can present with lymphadenopathy. Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare but life-threatening conditions involving severe blistering and peeling of the skin and mucous membranes. These conditions can also cause fever, flu-like symptoms, and swollen glands.

What to Do If You Experience Swollen Lymph Nodes

If you are taking omeprazole and notice swollen lymph nodes, especially accompanied by fever, a rash, or any other signs of a systemic reaction, you should seek immediate medical help. Do not stop taking the medication abruptly without consulting your doctor, as this could have unintended consequences, but do inform them of your symptoms right away. Your healthcare provider will need to perform an assessment to determine if the omeprazole is the cause and to rule out other potential etiologies, such as an infection or another underlying medical condition.

Comparison of Lymphadenopathy Causes


Feature	Drug-Induced Lymphadenopathy (e.g., DRESS)	Common Infection (e.g., Cold, Strep)
Onset	Delayed, typically weeks to months after starting the drug.	Rapid, within days of infection.
Associated Symptoms	Often accompanied by fever, widespread rash, and organ involvement (e.g., liver, kidneys).	Typically presents with localized symptoms like sore throat, cough, or ear pain.
Node Location	Can be generalized (neck, armpits, groin) and significant.	Usually localized to the area near the infection.
Severity	Potentially life-threatening, requiring prompt medical intervention.	Generally self-limiting and resolves with the infection.
Management	Discontinuation of the causative drug and possible hospitalization.	May require rest, over-the-counter pain relievers, and antibiotics for bacterial infections.

Conclusion

While omeprazole does cause swollen lymph nodes in very rare cases, it is critical to recognize this as a sign of a serious, systemic adverse reaction rather than a simple, benign side effect. The appearance of lymphadenopathy alongside other symptoms like fever and a widespread rash should immediately raise suspicion of DRESS syndrome or another severe hypersensitivity reaction. Never ignore these signs. Prompt communication with your doctor is the most important step to ensure a correct diagnosis and appropriate treatment. If you are concerned about any side effects while taking omeprazole, discuss them with your healthcare provider to ensure your safety and well-being. For more detailed information on drug-induced hypersensitivity, the National Institutes of Health (NIH) is an excellent resource.

When to Seek Medical Attention

You develop a widespread rash or skin blistering. These can be indicators of serious skin conditions like SJS or DRESS.
You experience fever, chills, or flu-like symptoms. A persistent, unexplained fever is a hallmark of systemic drug reactions.
The swelling is accompanied by difficulty breathing, swallowing, or throat tightness. These are signs of a severe allergic reaction (anaphylaxis).
You have signs of organ problems, such as yellowing of the skin or eyes (jaundice), dark urine, or changes in urination. Organ involvement is a defining feature of DRESS.
The swollen lymph nodes are hard, fixed, or continue to enlarge over time. This requires investigation to rule out other, unrelated conditions.

Frequently Asked Questions

No, swollen lymph nodes are not a common side effect of omeprazole. When they occur, it is a rare and serious finding that indicates a systemic immune response, often associated with a severe allergic or hypersensitivity reaction.

DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) syndrome is a rare but severe hypersensitivity reaction to medication. It is characterized by fever, a widespread rash, swollen lymph nodes (lymphadenopathy), and internal organ damage.

The onset of DRESS syndrome is typically delayed, appearing weeks to months after you start taking the medication. Patients with prior exposure might experience it sooner.

If you develop swollen lymph nodes while on omeprazole, you should seek immediate medical attention. Your doctor will determine if the medication is the cause and advise you on the next steps. Do not stop taking it without professional guidance.

Initial signs of a serious reaction can include fever, a new or worsening rash, chills, and flu-like symptoms, which may precede or accompany swollen glands. You might also notice signs of organ issues, like changes in urination or appetite.

Yes, in rare cases, omeprazole can cause other severe skin reactions like Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), which involve severe blistering and peeling of the skin.

Yes, swollen lymph nodes can be caused by many factors, including common infections like a cold or flu. It is crucial for a healthcare provider to properly diagnose the cause, as not all swollen lymph nodes are related to the medication.