DRESS syndrome stands for Drug Reaction (or Rash) with Eosinophilia and Systemic Symptoms. The term was coined in a 1996 report in an attempt to simplify terminology for a syndrome recognized as early as 1959. It is a syndrome, caused by exposure to certain medications, that may cause a rash, fever, inflammation of internal organs, lymphadenopathy, and characteristic hematologic abnormalities such as eosinophilia, thrombocytopenia, and atypical lymphocytosis. The syndrome carries about a 10% mortality.  Treatment consists of stopping the offending medication and providing supportive care. Systemic steroids are commonly used as well; however, there are no controlled clinical trials to assess the efficacy of this treatment. 
DRESS is one of several terms that have been used to describe a severe idiosyncratic reaction to a drug that is characterized by a long latency of onset after exposure to the offending medication, a rash, involvement of internal organs, hematologic abnormalities, and systemic illness. Other synonymous names and acronyms include HHS (Hypersensitivity Syndrome), AHS (Anticonvulsant Hypersensitivity Syndrome), DIHS (Drug-Induced Hypersensitivity Syndrome), DIDMOHS (Drug-Induced Delayed Multiorgan Hypersensitivity Syndrome), and Drug-Induced Pseudolymphoma.
The symptoms of DRESS syndrome usually begin several weeks after exposure to the offending drug. There is no gold standard for diagnosis, and at least two diagnostic criteria have been proposed. The RegiSCAR criteria  and the Japanese consensus group criteria are detailed in the table below.
|RegiSCAR inclusion criteria for DRESS syndrome. Three of the four starred criteria required for diagnosis||Japanese consensus group diagnostic criteria for DIHS. Seven criteria needed for diagnosis of DIHS or the first five criteria required for diagnosis of atypical DIHS|
|Hospitalization||Maculopapular rash developing > 3 weeks after starting the suspected drug|
|Reaction suspected to be drug-related||Prolonged clinical symptoms 2 weeks after discontinuation of the suspected drug|
|Acute Rash*||Fever > 38° C|
|Fever > 38° C*||Liver abnormalities (ALT > 100 U/L) or other organ involvement|
|Lymphadenopathy in at least two sites*||Leukocyte abnormalities|
|Involvement of at least one internal organ*||Leukocytosis ( > 11 x 109/L)|
|Blood count abnormalities (lymphopenia or lymphocytosis*, eosinophilia*, thrombocytopenia*)||Atypical lymphocytosis (>5%)|
|Human herpesvirus 6 reactivation|
Symptoms may be severe and involve many different organs. In a retrospective Taiwanese cohort study of 60 patients,the following incidences were observed.
|Incidence of organ involvement in DRESS syndrome |
|Organ||Percent of patients with involvement|
|Incidence of hematologic abnormalities in DRESS syndrome |
|Abnormality||Percent of patients with abnormality|
Drugs that commonly induce DRESS syndrome include phenobarbital, carbamazepine, phenytoin, lamotrigine, minocycline, sulfonamides, allopurinol, modafinil and dapsone. It has been associated with HHV6 
- Bocquet H, Bagot M, Roujeau JC (December 1996). "Drug-induced pseudolymphoma and drug hypersensitivity syndrome (Drug Rash with Eosinophilia and Systemic Symptoms: DRESS)". Semin Cutan Med Surg 15 (4): 250–7. doi:10.1016/S1085-5629(96)80038-1. PMID 9069593.
- Saltzstein SL, Ackerman LV (1959). "Lymphadenopathy induced by anticonvulsant drugs and mimicking clinically pathologically malignant lymphomas". Cancer 12 (1): 164–82. doi:10.1002/1097-0142(195901/02)12:1<164::AID-CNCR2820120122>3.0.CO;2-Y. PMID 13618867.
- Walsh SA, Creamer D (January 2011). "Drug reaction with eosinophilia and systemic symptoms (DRESS): a clinical update and review of current thinking". Clinical and Experimental Dermatology 36 (1): 6–11. doi:10.1111/j.1365-2230.2010.03967.x. PMID 21143513.
- Ganeva M, et al (2008). "Carbamazepine-induced drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome: report of four cases and brief review". International Journal of Dermatology 47 (8): 853–860. doi:10.1111/j.1365-4632.2008.03637.x. PMID 18717872.
- Kardaun SH, Sidoroff A, Valeyrie-Allanore L. et al (2007). "Variability in the clinical pattern of cutaneous side-effects of drugs with systemic symptoms: does a DRESS syndrome really exist?". Response Br J Dermatol 156 (3): 609–610. doi:10.1111/j.1365-2133.2006.07704.x. PMID 17300272.
- Shiohara T, Iijima M, Ikezawa Z, Hashimoto K. (2007). "The diagnosis of DRESS syndrome has been sufficiently established on the basis of typical clinical features and viral reactivations". Response Br J Dermatol 156 (5): 1045–92. doi:10.1111/j.1365-2133.2007.07807.x. PMID 17381452.
- Chen YC, Chiu HC, Chu CY (2010). "Drug Reaction With Eosinophilia and Systemic Symptoms: A retrospective study of 60 cases". Arch Dermatol 146 (12): 1373–1379. doi:10.1001/archdermatol.2010.198. PMID 20713773.
- Allam, JP; Paus T, Reichel C et al. (Sep–Oct 2004). "DRESS syndrome associated with carbamazepine and phenytoin". European Journal of Dermatology 14 (5): 339–342. PMID 15358574.
- "Tetracycline (doxycycline, minocycline)".
- Markel, A (October 2005). "Allopurinol-induced DRESS syndrome". Israel Medical Association Journal 7 (10): 656–660. PMID 16259349.
- Volume 14, Issue 8, Pages 498-500 (December 2003)