In medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, a drug eruption is an adverse drug reaction

Adverse drug reaction

An adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dosage. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs...

 of the skin

Human skin

The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...

. Most drug-induced cutaneous reactions are mild and disappear when the offending drug is withdrawn. Drugs can also cause hair

Hair disease

Hair diseases are disorders primarily associated with the follicles of the hair.An example is hypertrichosis.Many hair diseases can be associated with distinct underlying disorders.Piedra are fungal diseases.-External links:...

 and nail

Nail disease

Nail diseases are distinct from diseases of the skin. Although nails are a skin appendage, they have their own signs and symptoms which may relate to other medical conditions. Nail conditions that show signs of infection or inflammation require medical assistance...

 changes, affect the mucous membranes, or cause itching without outward skin changes.

Diagnosis

Drug eruptions are diagnosed mainly from the medical history

Medical history

The medical history or anamnesis of a patient is information gained by a physician by asking specific questions, either of the patient or of other people who know the person and can give suitable information , with the aim of obtaining information useful in formulating a diagnosis and providing...

 and clinical examination. However, they can mimic a wide range of other conditions, thus delaying diagnosis (for example, in drug-induced lupus erythematosus

Drug-induced lupus erythematosus

Drug-induced lupus erythematosus is an autoimmune disorder caused by chronic use of certain drugs. These drugs cause an autoimmune response producing symptoms similar to those of SLE...

, or the acne

Acne

Acne is a general term used for acneiform eruptions. It is usually used as a synonym for acne vulgaris, but may also refer to:*Acne aestivalis*Acne conglobata*Acne cosmetica*Acne fulminans*Acne keloidalis nuchae*Acne mechanica...

-like rash caused by erlotinib

Erlotinib

Erlotinib hydrochloride is a drug used to treat non-small cell lung cancer, pancreatic cancer and several other types of cancer. It is a reversible tyrosine kinase inhibitor, which acts on the epidermal growth factor receptor . It is marketed in the United States by Genentech and OSI...

). A skin biopsy

Skin biopsy

Skin biopsy is a biopsy technique in which a skin lesion is removed and sent to the pathologist to render a microscopic diagnosis. It is usually done under local anesthetic in a physician's office, and results are often available in 4 to 10 days. It is commonly performed by dermatologists. Skin...

, blood test

Blood test

A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....

s or immunological

Immunology

Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. It deals with the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders ; the...

 tests can also be useful. If the causative agent can not be withdrawn, the symptoms should be relieved as much as possible.

It is estimated that 2—3 percent of hospitalised patients are affected by a drug eruption, and that serious drug eruptions occur in around 1 in 1000 patients.

Classification

The drug eruption can be an expected adverse effect or an unexpected effect (idiosyncratic).

Some of the most severe and life-threatening examples of drug eruptions are erythema multiforme

Erythema multiforme

Erythema multiforme is a skin condition of unknown cause, possibly mediated by deposition of immune complex in the superficial microvasculature of the skin and oral mucous membrane that usually follows an infection or drug exposure...

, Stevens–Johnson syndrome, toxic epidermal necrolysis

Toxic epidermal necrolysis

Toxic epidermal necrolysis is a rare, life-threatening dermatological condition that is usually induced by a reaction to medications...

, hypersensitivity vasculitis, DRESS syndrome

DRESS syndrome

DRESS syndrome stands for Drug Reaction 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...

, erythroderma

Erythroderma

Erythroderma is an inflammatory skin disease with erythema and scaling that affects nearly the entire cutaneous surface....

 and exanthematous pustulosis.

By appearance

The most common type of eruption is a morbilliform

Morbilliform

The term morbilliform refers to a rash that looks like measles. The rash consists of macular lesions that are red and usually 2-10 mm in diameter but may be confluent in places...

 (resembling measles

Measles

Measles, also known as rubeola or morbilli, is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses...

) or erythematous rash, but the appearance may also be urticaria

Urticaria

Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

l, papulosquamous

Papulosquamous disorder

A papulosquamous disorder is a condition which presents with both papules and scales, or both scaly papules and plaques.Examples include psoriasis and lichen planus.-External links:* http://cchs-dl.slis.ua.edu/clinical/dermatology/papulosquamous/index.htm...

, pustular, purpuric

Purpura

Purpura is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin...

, bullous (with blisters) or lichenoid

Lichenoid eruption

A lichenoid eruption is a skin disease characterized by damage and infiltration between the epidermis and dermis.Examples include lichen planus, lichen sclerosus and lichen nitidus. It can also be associated with abrasion or drug use. It has been observed in conjunction with the use of proton pump...

. Angioedema

Angioedema

Angioedema or Quincke's edema is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis...

 can also be drug-induced (most notably, by angiotensin converting enzyme inhibitors).

By mechanism

The underlying mechanism can be immunological (such as in drug allergie

Drug allergy

A drug allergy is an allergy to a drug, most commonly a medication. Medical attention should be sought immediately if an allergic reaction is suspected....

s) or non-immunological (for example, in photodermatitis

Photodermatitis

Photodermatitis, sometimes referred to as "sun poisoning" or photoallergy is a form of allergic contact dermatitis in which the allergen must be activated by light to sensitize the allergic response, and to cause a rash or other systemic effects on subsequent exposure...

 or as a side effect of anticoagulants). A fixed drug eruption is the term for a drug eruption that occurs in the same skin area every time the person is exposed to the drug. Eruptions can occur frequently with a certain drug (for example, with phenytoin

Phenytoin

Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...

), or be very rare (for example, Sweet's syndrome following the administration of colony-stimulating factor

Colony-stimulating factor

Colony-stimulating factors are secreted glycoproteins that bind to receptor proteins on the surfaces of hemopoietic stem cells, thereby activating intracellular signaling pathways that can cause the cells to proliferate and differentiate into a specific kind of blood cell Colony-stimulating...

s).

By drug

The culprit can be both a prescription drug

Prescription drug

A prescription medication is a licensed medicine that is regulated by legislation to require a medical prescription before it can be obtained. The term is used to distinguish it from over-the-counter drugs which can be obtained without a prescription...

 or an over-the-counter medication.

Examples of common drugs causing drug eruptions are antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s and other antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 drugs, sulfa drugs, nonsteroidal anti-inflammatory drugs (NSAIDs), biopharmaceutical

Biopharmaceutical

Biopharmaceuticals are medical drugs produced using biotechnology. They include proteins , nucleic acids and living microorganisms like virus and bacteria where the virulence of viruses and bacteria is reduced by the process of attenuation, they can be used for therapeutic or in vivo diagnostic...

s, chemotherapy

Chemotherapy

Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

 agents, anticonvulsants, and psychotropic drugs. Common examples include photodermatitis due to local NSAIDs (such as piroxicam

Piroxicam

Piroxicam is a non-steroidal anti-inflammatory drug of the oxicam class used to relieve the symptoms of rheumatoid and osteoarthritis, primary dysmenorrhoea, postoperative pain; and act as an analgesic, especially where there is an inflammatory component...

) or due to antibiotics (such as minocycline

Minocycline

Minocycline is a broad-spectrum tetracycline antibiotic, and has a broader spectrum than the other members of the group. It is a bacteriostatic antibiotic, classified as a long-acting type...

), and the rash following ampicillin

Ampicillin

Ampicillin is a beta-lactam antibiotic that has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against Gram-positive organisms such as staphylococci and streptococci...

 in cases of mononucleosis

Infectious mononucleosis

Infectious mononucleosis is an infectious, widespread viral...

.