What medications cause lymph nodes to swell? A guide to drug-induced reactions

October 8, 2025 •

4 min read

While infections are a common cause of swollen lymph nodes, an estimated 2-10% of adverse drug reactions involve the lymphatic system. This specific reaction is known as drug-induced lymphadenopathy, and several types of medications cause lymph nodes to swell as an uncommon but possible side effect.

Quick Summary

Certain medications, including some anticonvulsants and antibiotics, can trigger a benign enlargement of lymph nodes or more severe hypersensitivity syndromes like DRESS, requiring careful medical evaluation.

Key Points

Drug-Induced Lymphadenopathy: The swelling of lymph nodes can be an uncommon adverse reaction to a variety of medications, not just a sign of infection.
Primary Offenders: Anticonvulsants (phenytoin, carbamazepine), antibiotics (penicillins, sulfonamides), and allopurinol are among the most frequent culprits.
Pseudolymphoma Risk: Certain drugs, particularly phenytoin, can cause a reversible lymphadenopathy that mimics malignant lymphoma, requiring careful diagnosis to avoid misidentification.
DRESS Syndrome: In more severe cases, lymphadenopathy is a symptom of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), a life-threatening hypersensitivity reaction involving rash and organ damage.
Delayed Onset: Symptoms often appear with a delayed onset, sometimes weeks or months after beginning a new medication.
Immediate Medical Consultation: If you notice swollen lymph nodes after starting a new drug, contact your doctor immediately but do not stop the medication without medical advice.
Diagnosis is Key: A detailed drug history and potential biopsy are necessary to distinguish drug-induced reactions from other causes of lymph node swelling.
Typically Reversible: The lymphadenopathy usually subsides after discontinuing the offending drug under a doctor's supervision.

Understanding Drug-Induced Lymphadenopathy

Drug-induced lymphadenopathy is the medical term for the enlargement of lymph nodes caused by a reaction to a medication. This condition is often benign, but it can sometimes mimic more serious conditions, including malignant lymphoma. It is crucial for both patients and healthcare providers to recognize the link between certain medications and lymph node swelling to ensure an accurate diagnosis and treatment plan.

The reaction that leads to lymphadenopathy can be part of a broader hypersensitivity response, where the immune system overreacts to the drug. In milder cases, it may resolve shortly after the offending medication is stopped. In more severe instances, it can be a feature of a life-threatening condition known as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome.

Key Culprit Medications Causing Lymph Node Swelling

Several classes of drugs are known to be associated with lymphadenopathy, with anticonvulsants being among the most frequently reported offenders. The following is a list of medications and drug classes commonly implicated in this side effect:

Anticonvulsants: This class includes drugs used to manage seizures and nerve pain. Classic examples are phenytoin (Dilantin), carbamazepine (Tegretol), and lamotrigine. These can induce a condition known as pseudolymphoma, where the lymphadenopathy closely resembles malignant lymphoma.
Antibiotics: Certain antibiotics have been linked to causing swollen lymph nodes, including penicillins, sulfonamides (e.g., trimethoprim-sulfamethoxazole), and cephalosporins. Minocycline, a tetracycline antibiotic, has also been implicated, often in cases of DRESS syndrome.
Allopurinol: This medication is used to treat gout and kidney stones. Hypersensitivity to allopurinol can cause fever, rash, eosinophilia, and swollen lymph nodes, in some cases as part of a severe reaction.
Antihypertensives: Some blood pressure medications can trigger this reaction. Examples include atenolol, captopril, and hydralazine.
Other Medications: Other drugs known to cause lymphadenopathy include quinidine (for irregular heart rhythms), sulindac (an NSAID for arthritis), and gold salts.

The Special Case of Anticonvulsant Pseudolymphoma

For decades, phenytoin has been linked to a specific type of drug-induced lymphadenopathy often termed "pseudolymphoma". This condition causes lymph node enlargement that can look pathologically identical to malignant lymphoma, leading to potential misdiagnosis and unnecessary treatment with chemotherapy. The syndrome is characterized by fever, rash, and generalized lymphadenopathy, but crucially, it typically regresses upon withdrawal of the anticonvulsant. Proper diagnosis hinges on recognizing the history of drug exposure and ruling out malignancy through careful evaluation. Long-term follow-up is sometimes necessary to monitor for any true malignant transformation, though this is rare.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Syndrome

DRESS is a severe, potentially life-threatening multi-organ hypersensitivity reaction that commonly includes lymphadenopathy as one of its key features. This syndrome has a characteristic delayed onset, with symptoms appearing 2 to 8 weeks after starting the drug, which can make connecting it to a medication challenging.

Common DRESS Symptoms

Fever
Widespread skin rash (often morbilliform, or measles-like)
Lymphadenopathy (generalized)
Eosinophilia (high count of eosinophils, a type of white blood cell)
Organ involvement (e.g., hepatitis, nephritis, pneumonitis)

Management of DRESS involves immediate discontinuation of the suspected drug and providing supportive care, often with corticosteroids to manage the hypersensitivity reaction. Because of its severity, early recognition is vital.

Comparison of Drug-Induced Lymphatic Reactions


Feature	Drug-Induced Pseudolymphoma	DRESS Syndrome
Mechanism	Benign hyperplasia in response to drug; mimics lymphoma	Severe, multi-organ hypersensitivity reaction
Associated Drugs	Primarily aromatic anticonvulsants (phenytoin, carbamazepine)	Wide range, including anticonvulsants, allopurinol, antibiotics, and NSAIDs
Onset	Can occur weeks to years after starting the drug	Typically 2–8 weeks after drug initiation
Symptoms	Fever, rash, lymphadenopathy, hepatosplenomegaly	Fever, extensive rash, lymphadenopathy, organ dysfunction
Severity	Generally benign and reversible	Potentially life-threatening, with high mortality if untreated
Diagnostic Challenge	Histologically similar to true lymphoma	Broad, non-specific symptoms can mimic other illnesses
Treatment	Withdrawal of the offending drug	Immediate drug withdrawal, often with systemic corticosteroids

What to Do If You Suspect a Medication Is Causing Swollen Lymph Nodes

If you develop swollen lymph nodes after starting a new medication, it is essential to contact your healthcare provider for an evaluation. They can review your medication history, perform a physical examination, and order tests to determine the cause.

Diagnostic Process

Detailed Medical History: Your doctor will take a thorough history, focusing on new medications, dosing changes, and when symptoms began.
Physical Examination: Your doctor will check for enlarged lymph nodes, rashes, or other signs of systemic illness.
Blood Work: This can include a complete blood count (CBC) to check for eosinophilia or other abnormalities common in drug reactions.
Biopsy (if needed): In some cases, a lymph node biopsy may be necessary to rule out malignancy, especially if a drug-induced pseudolymphoma is suspected.

Crucially, do not stop taking a prescribed medication on your own without first consulting your doctor, as abruptly discontinuing some drugs can be dangerous.

Conclusion

While alarming, swollen lymph nodes can be an adverse reaction to a medication. The condition, known as drug-induced lymphadenopathy, can range from a mild, reversible swelling to a feature of a severe, systemic hypersensitivity reaction like DRESS syndrome. Recognizing the symptoms and informing your doctor of all medications you are taking is the most critical step. With proper medical evaluation and management, including the discontinuation of the offending drug, the condition typically resolves. The diagnostic journey requires careful consideration of the patient's drug history to differentiate it from other serious conditions, ensuring appropriate treatment is administered.

For more detailed clinical information on lymphadenopathy, healthcare professionals can consult resources such as the National Center for Biotechnology Information (NCBI) Bookshelf.

NCBI Bookshelf: Lymphadenopathy

Frequently Asked Questions

Drug-induced lymphadenopathy is the benign enlargement of lymph nodes that occurs as an adverse side effect or hypersensitivity reaction to a medication.

Yes, some antibiotics can cause swollen lymph nodes as a side effect. Examples include penicillins, cephalosporins, and sulfonamides.

It can range in severity. While some cases are benign and reversible, it can also be a symptom of a severe, potentially life-threatening condition like DRESS syndrome, which requires urgent medical attention.

DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) is a severe, systemic hypersensitivity reaction to a drug characterized by fever, rash, lymphadenopathy, eosinophilia, and multi-organ involvement.

Pseudolymphoma is a drug-induced reaction, often caused by anticonvulsants, that causes lymph node swelling that can histologically mimic malignant lymphoma but is a benign and reversible condition.

The onset can be delayed, often appearing weeks to months after starting the medication. This prolonged latency period is a key feature of DRESS syndrome.

You should contact your healthcare provider immediately for an evaluation. Do not stop taking the medication without consulting your doctor first.

In most cases, the lymphadenopathy will subside after the offending medication is discontinued under medical supervision.

A doctor will take a detailed drug history, perform a physical exam, and may order blood tests (like a CBC) or a lymph node biopsy to confirm the diagnosis and rule out other causes.

Yes, other medications, including some tumor necrosis factor-alpha inhibitors, antidepressants, and antihypertensives, have also been associated with this condition.