From the Guidelines
Rashes should be described based on their appearance, distribution, and associated symptoms, with key characteristics including color, texture, size, shape, borders, and whether they are itchy, painful, or accompanied by other symptoms like fever. When evaluating a rash, it's essential to consider its potential causes, which can be allergic, infectious, autoimmune, or environmental 1. The description of a rash can help guide its diagnosis and treatment. For instance, a rash characterized by erythema and vesiculation may indicate an acute phase of contact dermatitis, while dryness, lichenification, and fissuring may suggest a chronic phase 1.
In terms of specific characteristics, a rash can be described as maculopapular (flat red areas with raised bumps), vesicular (small fluid-filled blisters), urticarial (hives), or eczematous (dry, itchy, inflamed skin) 1. The distribution pattern of the rash, whether it's localized or generalized, and its pattern of spread are also crucial details. Additionally, noting whether the rash is blanching (temporarily disappears when pressed) or if lesions are discrete or confluent can aid in diagnosis.
Given the potential for rashes to be caused by various factors, including infectious conditions, it's critical to consider the possibility of an infectious etiology, such as in the case of a diffuse papulovesicular rash without other apparent cause, as described by the Centers for Disease Control and Prevention 1. The management of rashes, therefore, requires a thorough evaluation to identify the underlying cause and select the appropriate treatment, which may include topical corticosteroids, antihistamines, or antifungal creams, depending on the specific diagnosis. Severe or spreading rashes, especially those accompanied by fever or other systemic symptoms, necessitate prompt medical evaluation to ensure timely and effective treatment.
From the FDA Drug Label
Hypersensitivity AlIergic reactions in the form of rash, urticaria, angioedema, and, rarely, erythema multiforme, Stevens-Johnson syndrome, or toxic epidermal necrolysis have been observed.
- Rash descriptions include:
- Rash
- Urticaria
- Angioedema
- Erythema multiforme
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis These reactions usually subsided upon discontinuation of the drug 2
From the Research
Rash Descriptions
- Cephalosporins are commonly used antibiotics that can cause hypersensitivity reactions, including severe cutaneous adverse reactions and anaphylaxis 3.
- Patients allergic to cephalosporins may react to other beta-lactams with common R1 side chains, but can tolerate cephalosporins with disparate R1 side chains 3, 4.
- Skin testing for cephalosporins has not been well validated, but appears to have a good negative predictive value for cephalosporins with disparate R1 side chains 3, 5.
- In vitro tests, including basophil activation tests, have lower sensitivity compared to skin testing 3.
- Rapid drug desensitization procedures are safe and effective for immediate and some nonimmediate cephalosporin reactions 3.
- The use of cephalosporins in penicillin-allergic patients is considered safe, especially with third- or fourth-generation cephalosporins or cephalosporins with dissimilar side chains than the offending penicillin 6, 4, 7.
- The overall cross-reactivity rate between penicillins and cephalosporins is approximately 1% when using first-generation cephalosporins or cephalosporins with similar R1 side chains 4.
- A rash can occur as a reaction to cephalosporins, as seen in one non-penicillin-allergic patient who developed a rash while receiving a cephalosporin 6.