Allopurinol hypersensitivity syndrome
Other names	AHS
Allopurinol
Symptoms	Fever, Cutaneous Reaction,Eosinophilia,Acute Renal Failure.[1]
Treatment	SystematicCorticosteroids.[2]
Frequency	Rare

Allopurinol hypersensitivity syndrome(AHS) typically occurs in persons with preexistingkidney failure.^[3]: 119 Weeks to months afterallopurinol is begun, the patient develops amorbilliform eruption^[3]: 119 or, less commonly, develops one of the far more serious and potentially lethalsevere cutaneous adverse reactions viz., theDRESS syndrome,Stevens Johnson syndrome, ortoxic epidermal necrolysis.^[4] About 1 in 1000 patients receiving allopurinol are affected, and mortality rates have been reported to be between 20% and 25%.^[5]

Allopurinol has been linked to severe cutaneous adverse reactions (SCAR),toxic epidermal necrolysis,Stevens-Johnson syndrome, and drug reaction with eosinophilia and systemic symptoms (DRESS). Clinically, these syndromes are similar in that they both involve fever,eosinophilia, rash, and dysfunction of theliver andkidneys.^[1]

In a retrospective case-control study, it was shown that an increased initial dose ofallopurinol was linked to AHS.^[6]

Oxypurinol is quickly transformed fromallopurinol and then eliminated by thekidneys. The mean half-life ofoxypurinol in patients with normal kidney function is 23 hours, although 95% of patients have half-lives between 9 and 38 hours.^[7] The half-life ofoxypurinol increases with decreasing kidney function, allowing it to build up over an extended period of time and reach higher steady-state concentrations; among those suffering fromanuria, nearly nooxypurinol is eliminated.^[8] The first report of the link between kidney impairment and AHS was found in a 1984 case series, wherein 58 patients with AHS had demonstrated signs of kidney impairment before startingallopurinol treatment.^[9] Additionally, among the most common co-morbidities in a comprehensive analysis of all 901 reported cases of AHS,chronic kidney disease was present in 182 out of 376 (48%) patients.^[10]

After beginningallopurinol, allopurinol hypersensitivity syndrome usually manifests itself in the first few weeks to months. Ninety percent of the 901 documented cases of AHS in the largest review to date began within the first 8 to 9 weeks of startingallopurinol, with a median time to onset of 3 weeks.^[10]

TheHLA-B gene belongs to the family of genes called theHLA complex. Anodds ratio of 80–580 has been reported to link the HLA-B*58:01 allele to a higher risk of allopurinol-inducedDRESS andSJS/TEN.^[11][12]

Preventative measures include using alternative drugs,genetic screening, and modifying the starting dose.^[8]

Treatment consists of discontinuingallopurinol and providing supportive care.Immunomodulatory treatments and systemicsteroids might be helpful. Whether a patient hastoxic epidermal necrolysis,Stevens-Johnson syndrome, ordrug reaction with eosinophilia and systemic symptoms will determine the course of treatment.^[2]Allopurinol should not be given to patients who develop AHS again; instead, alternativeurate-lowering medications, such asfebuxostat, may be taken into consideration.^[5]

• Severe cutaneous adverse reactions
• List of cutaneous conditions

• Arellano, Félix; Sacristán, José A. (1993). "Allopurinol Hypersensitivity Syndrome: A Review".Annals of Pharmacotherapy.27 (3):337–343.doi:10.1177/106002809302700317.ISSN 1060-0280.PMID 8453174.S2CID 24088018.
• Lupton, George P.; Odom, Richard B. (1979). "The allopurinol hypersensitivity syndrome".Journal of the American Academy of Dermatology.1 (4). Elsevier BV:365–374.doi:10.1016/s0190-9622(79)70031-4.ISSN 0190-9622.PMID 159913.

• Allopurinol - Mayo Clinic
• Allopurinol - WebMD

• Drug eruptions
• Syndromes

• Articles with short description
• Short description matches Wikidata