Summary about Disease
Fixed drug eruption (FDE) is a distinct type of drug-induced skin reaction. It characteristically appears as a solitary or multiple, sharply demarcated, round or oval, dusky-red plaques. The lesions recur at the same site on the skin or mucous membranes each time the offending drug is taken. The eruption typically resolves with post-inflammatory hyperpigmentation.
Symptoms
Well-defined, round or oval, red or purplish plaques.
May blister or form bullae (large blisters) in severe cases.
Itching, burning, or stinging sensation at the site of the lesion.
Lesions commonly appear on the genitals, lips, hands, feet, and trunk, but can occur anywhere.
After healing, the affected area often leaves a dark brown or gray discoloration (post-inflammatory hyperpigmentation).
Causes
FDE is caused by an adverse reaction to a medication. Common causative drugs include:
Antibiotics (especially tetracyclines, sulfonamides)
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Paracetamol (acetaminophen)
Barbiturates
Antifungals
Oral Contraceptives The reaction is triggered by the drug, and the lesions will reappear at the same site(s) each time the individual takes the drug.
Medicine Used
Topical Corticosteroids: To reduce inflammation and itching.
Topical Emollients: To moisturize the skin and aid in healing.
Oral Antihistamines: To relieve itching.
In severe cases, Oral Corticosteroids: May be prescribed for a short course to reduce inflammation.
Antibiotics: May be used if secondary bacterial infection occurs. The most important treatment is to identify and discontinue the offending drug.
Is Communicable
No, fixed drug eruption is not communicable. It is an individual reaction to a specific medication and cannot be spread to others.
Precautions
Identify and Avoid the Offending Drug: The most important precaution is to identify the drug that caused the eruption and avoid it in the future.
Inform Healthcare Providers: Always inform your doctors, dentists, and pharmacists about any drug allergies or adverse reactions you have experienced, including fixed drug eruptions.
Carry Identification: Consider wearing a medical alert bracelet or carrying a card that lists the drug you are allergic to.
Read Medication Labels: Carefully read the labels of all medications, including over-the-counter drugs, to check for ingredients you need to avoid.
How long does an outbreak last?
Without re-exposure to the drug: lesions typically resolve within days to a few weeks after stopping the medication.
Hyperpigmentation (darkening of the skin) may persist for months or even years after the lesions have healed.
How is it diagnosed?
Clinical Examination: Diagnosis is primarily based on the characteristic appearance and history of recurring lesions at the same site.
Drug History: A thorough review of the patient's medications, including over-the-counter drugs and supplements, is crucial.
Patch Testing: Can be used to identify the culprit drug, but is not always conclusive.
Oral Challenge: In some cases, a controlled oral challenge with the suspected drug may be performed under medical supervision to confirm the diagnosis. This is risky and should only be done when absolutely necessary and with appropriate precautions.
Biopsy: A skin biopsy may be performed to confirm the diagnosis and rule out other conditions.
Timeline of Symptoms
Initial Exposure: Upon first exposure to the offending drug, the eruption may appear within hours to days.
Subsequent Exposure: With each subsequent exposure to the same drug, the eruption will typically reappear at the same site within 30 minutes to 8 hours.
Resolution: After stopping the drug, the lesions typically resolve within days to a few weeks.
Hyperpigmentation: Post-inflammatory hyperpigmentation can last for months to years.
Important Considerations
Re-exposure: Even a small amount of the offending drug can trigger a recurrence.
Cross-reactivity: Be aware of potential cross-reactivity with drugs that are chemically similar to the offending agent.
Multiple Drugs: It is possible to have FDE to multiple drugs simultaneously.
Location: The location of the lesions can sometimes provide clues to the causative drug (e.g., perioral lesions may be related to certain topical medications).
Severe Cases: Severe cases of FDE can lead to blistering and systemic symptoms, requiring more aggressive treatment.