What are the other Names for this Condition? (Also known as/Synonyms)

• Medication-Induced Erythema Nodosum

What is Drug-Induced Erythema Nodosum? (Definition/Background Information)

• Erythema nodosum is a skin condition that causes painful red subcutaneous nodules. It may be caused by numerous factors including certain infectious diseases, pregnancy, inflammatory bowel disease, blood cancer, and many other disorders
• Drug-Induced Erythema Nodosum is caused by the use of certain medications, such as oral contraceptives, antibiotics, or certain anticonvulsants, among others. It may be considered as a reactive condition of the body to the specific medication
• The nodules in Drug-Induced Erythema Nodosum may occur on the legs and arms. Apart from cosmetic concerns in some individuals, no significant complications are noted in many cases
• Stopping or discontinuing the use of such medications may decrease progression of Drug-Induced Erythema Nodosum, or may result in a cure. The prognosis is good in a majority of cases with adequate treatment

Who gets Drug-Induced Erythema Nodosum? (Age and Sex Distribution)

• Drug-Induced Erythema Nodosum is a skin condition caused by a variety of medications that are administered for other underlying conditions. Hence, any individual of any age may be at risk for the same
• Both males and females are affected, although erythema nodosum is more often seen in females
• It can affect individuals of any ethnicity, race or region

What are the Risk Factors for Drug-Induced Erythema Nodosum? (Predisposing Factors)

The key risk factor for Drug-Induced Erythema Nodosum is the use of certain medications that cause the skin condition as a side effect. The medications observed to induce this abnormal skin growth/nodules include:

• Antibiotics that include amoxicillin, penicillin, tetracycline, and sulfonamide
• Sulfone antibiotics
• Birth-control pills and progestin
• Bromides and iodides
• Thyroid medication such as iodides
• Salicylates
• Barbiturates
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• TNF inhibitors used to treat inflammatory conditions
• BRAF inhibitors used to treat cancer

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Drug-Induced Erythema Nodosum? (Etiology)

The exact cause of development of Drug-Induced Erythema Nodosum is unknown. The condition can be defined as an adverse reaction of the body to certain medications that are used for various health conditions.

• It is believed that the offending drug potentially causes an abnormal cell-mediated immune response in the body, which results in the formation of the skin lesions
• Sometimes, the appearance of signs and symptoms due to the drug may not be observed immediately after starting the medication. The condition may develop after a certain period

What are the Signs and Symptoms of Drug-Induced Erythema Nodosum?

The onset of Drug-Induced Erythema Nodosum may be slow or rapid. In some cases, it may not be noted immediately, but may take some days to weeks. In some cases, it may take much longer for the manifestation of significant symptoms.

The signs and symptoms of Drug-Induced Erythema Nodosum may include:

• Presence of nodules beneath the skin
• They begin as flat, firm and red lumps measuring up to an inch on the body
• After a few days, the nodules turn purple; weeks later, they become flat and brownish patches
• Itching of skin
• The nodules are painful and may be present on any part of the body, especially on the legs, thighs, and buttocks

The severity of the signs and symptoms may be related to the type, dosage, and usage of the drug.

How is Drug-Induced Erythema Nodosum Diagnosed?

The following procedures may be used to diagnose Drug-Induced Erythema Nodosum:

• A complete physical examination and a thorough medical history (which includes the use of any drugs and topical applications)
• The healthcare provider may note that the condition gets better on stoppage of the medication
• Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Tissue biopsy, if necessary: A tissue/skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Note: In most cases, based on the signs and symptoms, a diagnosis can be made by the dermatologist through a physical examination and medical history study, without resorting to a biopsy.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Drug-Induced Erythema Nodosum?

Major complications associated with skin lesions of Drug-Induced Erythema Nodosum are not generally reported.

• The lesions or erythema nodosum are painful, more so when touched or pressed. The pain of walking or standing can interfere with work or ordinary life activities
• With chronic disease activity, the fibrosis or necrosis of fat cells can lead to scarring
• The deep reddish purple of active or resolved lesions may result in cosmetic issues leading to emotional stress

How is Drug-Induced Erythema Nodosum Treated?

Discontinuing the medication responsible for the side effect may result in a cure, or in improvement of Drug-Induced Erythema Nodosum. The following other treatment measures may be considered:

• Use of topical steroidal creams and lotions, as recommended by the healthcare provider
• Administration of systemic steroids
• Discontinuing the medication which triggered the erythema nodosum reaction
• Oral treatment with iodine medications
• Treatment with non-steroidal anti-inflammatory medications (NSAIDs) such as ibuprofen or indomethacin
• Providing reassurance and helping with feelings of stress and anxiety
• On treating the underlying cause, erythema nodosum usually resolves

Follow-up care with regular screening and check-ups are important and encouraged.

Note: If any of the prescribed treatment medication or methods cause ‘new’ stinging or burning symptoms, then it is important to discontinue the medication or method and immediately inform the healthcare provider.

A few self-care tips and home remedies that may prevent aggravation of the condition include:

• Completely avoiding scratching the affected areas (keep fingernails trimmed)
• Having a comfortable cool bath may help soothe the skin; but, it is important to avoid excessive washing and scrubbing of the skin
• Wear smooth cotton clothes
• Elevation of the legs when possible to decrease pain and swelling
• Using only mild perfumes, soaps, and detergents
• Drinking lots of water or fluids

How can Drug-Induced Erythema Nodosum be Prevented?

Current medical research has not established a method of preventing Drug-Induced Erythema Nodosum. However, the following may be observed:

• Drugs that cause erythema nodosum may be discontinued or alternative medications used
• Inform your physician if you are allergic to certain drugs
• Periodic monitoring or follow-up of the condition with the healthcare provider is recommended

What is the Prognosis of Drug-Induced Erythema Nodosum? (Outcomes/Resolutions)

• The prognosis for Drug-Induced Erythema Nodosum is usually good in many cases, upon discontinuation of the medication and adequate treatment of the skin condition (when needed). Apart from the skin rashes/nodules, no other significant symptoms are generally noted
• In some individuals, the symptoms may appear, subside, and then recur with time. Also, ulcerative lesions are difficult to treat. In such cases, symptomatic treatment may be provided to improve one’s quality of life

Additional and Relevant Useful Information for Drug-Induced Erythema Nodosum:

• Cleaning the skin too hard with strong chemicals or soaps may aggravate the skin condition. Care must be taken avoid strong soaps and chemicals that could potentially worsen the condition
• The presence of dirt on the body is not a causative factor for the condition. However, it helps to be clean and hygienic, which may help the condition from getting worse