DRESS Syndrome (Drug Reaction With Eosinophilia and Systemic Symptoms)

What happens in DRESS syndrome

DRESS is a T-cell-driven form of drug allergy. In susceptible people, a drug or its breakdown products activate immune cells that spread through the body, causing inflammation in the skin and internal organs. Raised eosinophils, a type of white blood cell, are common. Reactivation of herpes viruses, particularly human herpesvirus 6 (HHV-6), often occurs during the illness and may drive the prolonged, relapsing course.

Genetics plays a role. For example, the HLA-B*58:01 gene, more common in people of Han Chinese, Thai and Korean ancestry, greatly increases the risk of allopurinol-related DRESS and severe skin reactions. Testing before starting allopurinol is recommended for some groups.

Drugs that commonly cause DRESS

Symptoms

• fever, often the first sign, above 38 °C (100.4 °F)
• widespread red rash, often starting on the face, upper trunk and arms, then spreading to cover more than half the body; it may become scaly, blistered or purple
• facial swelling, especially around the eyes, which is a typical clue
• swollen lymph nodes in the neck, armpits or groin
• itching
• feeling very unwell and tired

Organ involvement

• Liver: the most commonly affected organ; hepatitis with raised liver enzymes, sometimes jaundice and liver failure
• Kidneys: acute kidney injury, especially with allopurinol
• Lungs: cough and breathlessness from pneumonitis
• Heart: myocarditis, which can occur late and be dangerous
• Other: thyroid, pancreas, muscles and brain

Diagnosis

There is no single test. Doctors use clinical features and scoring systems such as the RegiSCAR criteria, which consider fever, rash, lymph nodes, blood abnormalities, organ involvement, timing and recovery.

Tests include:

• complete blood count: eosinophilia and atypical lymphocytes
• liver and kidney function, urine tests
• heart tests (ECG, troponin, echocardiogram) if heart involvement is suspected
• skin biopsy to support the diagnosis and exclude other conditions
• tests to exclude infections that mimic DRESS, such as viral hepatitis, Epstein-Barr virus and others
• HHV-6 and other viral testing

DRESS vs other drug reactions

Treatment

1. Stop the suspected drug immediately, along with any non-essential medicines.
2. Hospital care: many people need admission, sometimes to intensive care or a burn unit.
3. Corticosteroids: systemic steroids are usually given for moderate to severe DRESS and tapered slowly over 6 to 8 weeks or longer, because rapid tapering can cause relapse.
4. Supportive care: fluids, nutrition, skin care with emollients, and treatment of organ complications.
5. Other treatments for severe or steroid-resistant cases: cyclosporine, IV immunoglobulin, or antiviral medicines in selected cases.

Complications

• liver failure, sometimes needing transplant
• kidney failure
• myocarditis
• relapses during steroid tapering
• long-term autoimmune conditions months to years later, including autoimmune thyroiditis, type 1 diabetes and lupus

The risk of death is estimated at up to about 10%, mostly from liver failure or heart involvement.

Prevention and living after DRESS

• Never take the causative drug again. Cross-reactions are common, especially among aromatic anti-seizure medicines (carbamazepine, phenytoin, phenobarbital, oxcarbazepine), so related drugs are also avoided.
• Make sure the reaction is recorded in all medical records and wear a medical alert bracelet.
• Close relatives may share genetic risk; some may benefit from testing before taking high-risk drugs.
• Have regular check-ups for thyroid function and blood sugar after recovery.

Frequently asked questions

What is DRESS syndrome?

DRESS syndrome is a severe allergic reaction to a medicine that causes fever, a widespread rash, facial swelling, swollen glands, a high eosinophil count and inflammation of organs such as the liver or kidneys. It typically starts 2 to 8 weeks after beginning a new drug.

Which drugs cause DRESS syndrome?

The most common triggers are allopurinol, anti-seizure medicines such as carbamazepine, phenytoin and lamotrigine, sulfonamide antibiotics, sulfasalazine, dapsone, minocycline and vancomycin. Many other medicines have been reported.

How long does DRESS syndrome last?

DRESS often lasts several weeks to months. Symptoms may relapse when steroids are tapered or even after initial improvement. Full recovery usually takes weeks to months, and some people develop autoimmune problems later.

Is DRESS syndrome fatal?

It can be. The death rate is estimated at up to about 10%, mostly from liver failure or heart inflammation. Early recognition, stopping the drug and prompt hospital care improve the outcome.

Can DRESS syndrome come back?

Yes, if the same drug or a closely related drug is taken again, often with a faster and more severe reaction. Relapses can also happen during steroid tapering. Avoid the causative drug and related medicines for life.