New research published in the JAMA Internal Medicine medical journal in July 2015 revealed that nearly five of every 1,000 patients who use drugs containing allopurinol to treat gout may experience hypersensitivity reactions, including the life-threatening reaction known as Stevens Johnson Syndrome or SJS. Hospitalizations related to allopurinol drugs occurred in two of every 1,000 users within the first month of use.

The research study was conducted in Taiwan and included information from 1,613,719 users of allopurinol drugs from Jan. 1, 2005, through Dec. 31, 2011. Over the course of the study, the annual incidence of hypersensitivity reactions including SJS reported showed a significant increase.

What Are Allopurinol Drugs?

Allopurinol is the main ingredient in the drugs Zyloprim and Alloprim. Allopurinol works by reducing the production of uric acid in the body and it is primarly used to treat gout and kidney stones. It is also used to decrease the levels of uric acid in individuals undergoing cancer treatment.

Among the most serious of hyperactivity reactions associated with allopurinol drugs are the skin conditions called Stevens Johnson Syndrome (SJS) and its more severe form known as Toxic Epidermal Necrolysis (TEN). For patients in the allopurinol study, most of these SJS or TEN reactions occurred within three months of initially starting the drug.

Various risk factors were identified that were linked to individuals being more susceptible to developing hypersensitivity reactions like SJS. Those most at-risk included females, individuals aged 60 or older, initial allopurinol dosing of 100mg/d or more, individuals with concurrent cardiovascular issues, and the use of allopurinol to treat asymptomatic hyperuricemia.

What is Stevens Johnson Syndrome?

Stevens Johnson Syndrome is an allergic skin reaction brought on by the body’s response to medications such as allopurinol drugs. The condition causes the skin and mucous membranes to blister and the subsequent cell death causes the epidermal layer of skin to separate from the dermis.

The main distinguishing characteristic between SJS and TEN is the percentage of the skin on the body that is affected. In SJS, usually less than 30% of the body is affected, where in TEN, 30% or more of the body is affected.

SJS symptoms often initially include a flu-like reaction, complete with fever, sore throat, and fatigue. Oral and mucosal lesions and ulcers usually begin to appear next, with the genital and anal regions sometimes also being affected.

Other drugs and medications in addition to allopurinol have been linked to SJS and TEN include:

• Pain relievers such as acetaminophen (Tylenol and others), ibuprofen (Advil, Motrin and others), and naproxen sodium (Aleve)
• Antibiotics and other medications to fight infection
• Anticonvulsants (Dilantin and others)
• Antipsychotics
• Radiation therapy
• Other drugs (Protonix, a proton pump inhibitor, and others)

Treatment for SJS and TEN

SJS and TEN are considered a dermatological emergency and hospitalization is required. Initially, treatment is similar to those with thermal burns. Supportive care is then given, such as IV fluids and nutrition, pain relief, and use of topical pain relief and antiseptics.

Stevens Johnson Syndrome has a mortality rate of approximately 5%, where those with Toxic Epidermal Necrolysis have an increased mortality rate of about 30-40%.

Individuals and families who have been affected by SJS and TEN as a result of allopurinol drugs may be eligible to file a SJS lawsuit against the manufacturer of the medication.