Medications and illicit drugs can cause multiple skin eruptions and reactions. The most serious of these are discussed elsewhere in THE MANUAL and include Stevens-Johnson syndrome and toxic epidermal necrolysis, hypersensitivity syndrome, serum sickness, exfoliative dermatitis, angioedema, anaphylaxis, and medication-induced vasculitis.
Medications can also be implicated in hair loss, lichen planus, erythema nodosum, pigmentation changes, systemic lupus erythematosus, photosensitivity reactions, pemphigus, and pemphigoid.
Other medication and drug reactions are classified by lesion type.
Symptoms and Signs of Drug Eruptions and Reactions
Symptoms and signs vary based on the cause and the specific reaction (see table Types of Drug Reactions and Typical Causative Agents).
Urticarial lesions (wheals or hives) are migratory, elevated, pruritic, reddish plaques caused by local dermal edema.
Photo provided by Thomas Habif, MD.
This photo shows acneiform rash on the chest caused by corticosteroid treatment.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
This photo shows a morbiliform eruption secondary to use of a medication.
Photo courtesy of Anar Mikailov, MD, FAAD.
This photo shows a dusky purple plaque with slight erythema and scale at the periphery.
Photo courtesy of Karen McKoy, MD.
Urticarial lesions (wheals or hives) are migratory, elevated, pruritic, reddish plaques caused by local dermal edema.
Photo provided by Thomas Habif, MD.
This photo shows acneiform rash on the chest caused by corticosteroid treatment.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
This photo shows a morbiliform eruption secondary to use of a medication.
Photo courtesy of Anar Mikailov, MD, FAAD.
This photo shows a dusky purple plaque with slight erythema and scale at the periphery.
Photo courtesy of Karen McKoy, MD.
Immune checkpoint inhibitors commonly cause drug eruptions or cutaneous symptoms (1). The most common are the following:
Less common examples include the following:
Psoriasiform dermatoses
Drug reaction with eosinophilia and systemic symptoms
Risks are highest with combinations of immune checkpoint inhibitors. When only single agents are used, risks are highest with inhibitors of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), followed by inhibitors of programmed death receptor 1 (PD1), then inhibitors of programmed cell death ligand 1 (PD-L1).
Symptoms and signs reference
1. Quach HT, Johnson DB, LeBoeuf NR, Zwerner JP, Dewan AK. Cutaneous adverse events caused by immune checkpoint inhibitors. J Am Acad Dermatol. 2021;85(4):956-966. doi:10.1016/j.jaad.2020.09.054
Diagnosis of Drug Eruptions and Reactions
Clinical evaluation and drug exposure history
Sometimes skin biopsy
A detailed history is often required for diagnosis, including recent use of over-the-counter medications and illicit drugs. Because the reaction may not occur until several days or even weeks after first exposure to a medication, it is important to consider all new medications and not only the one that has been most recently started.
No laboratory tests reliably aid diagnosis, although biopsy of affected skin is often suggestive.
Sensitivity can be definitively established only by rechallenge with the agent, which may be hazardous and unethical in patients who have had severe reactions. Occasionally, patch testing can be helpful in patients with fixed drug eruptions.
Treatment of Drug Eruptions and Reactions
Discontinuation of offending medication
Sometimes antihistamines and corticosteroids
Most drug reactions resolve when medications are stopped and require no further therapy. Whenever possible, chemically unrelated compounds should be substituted for suspect medications. If no substitute medication is available and if the reaction is a mild one, it might be necessary to continue the treatment under careful watch despite the reaction.
Pruritus and urticaria can be controlled with oral antihistamines and topical corticosteroids. For IgE-mediated reactions (eg, urticaria), desensitization can be considered when there is critical need for a medication.
Key Points
Because medications can cause a wide variety of reactions, medications should be considered as causes of almost any unexplained skin reaction.
Base the diagnosis primarily on clinical criteria, including a detailed history of prescription and over-the-counter medications.
Stop the suspected offending agent and treat symptoms as needed.
