It is a common hypersensitive reaction of the skin to exogenous and endogenous agents. One can get vascular dilation, redness, edema, and itching. From the skin it can also become systemic giving swelling over the body and can also cause angioedema which can be life-threatening.
- Ingestants– this includes NSAIDS, and chloroquine, foods like seafood, a coloring agent, eggs, spices, eggplant etc.
- Inhalants – pollens, plant hair animal dander.
- Injectants – drugs like antibiotic.
- Contactants – bee stings, bug bites, excreta
- Infections – bacterial
- Upper respiratory tract infection, urinary tract infection
- helminthiasis, amebiasis
- Systemic disease
- Systemic lupus erythematosus
- Patient can also go through the systemic symptoms
- Like rhinitis, difficulty in breathing, wheezing and abdominal pain may accompany skin lesions and are an indication of urgent treatment to avoid complication like edema in the larynx.
Complete blood workup has to be done with.