The toxicodermia is the set of skin reactions caused by the harmful effects of certain drugs or substances, whether they have been given orally, as topically or otherwise. Sometimes, they can also affect the mucous membranes. This effect can be caused by different types of drug compounds, thus making it important to identify to avoid. Symptoms and treatment depend on the type of toxicodermia who suffer, but the most common are: rash morbilliform, which often causes sudden and generalized rashes and itching, which may appear after several days of ingesting the drug, requiring treatment with corticosteroids and antihistamines; fixed drug eruption, causing purplish lesions in certain areas and can also take several days to express their reaction after taking the drug, requiring the same treatment as morbilliform rash; or Steven-Johnson syndrome and toxic epidermal necrolysis, consisting of high gravity and reactions that often require hospitalization and in most cases causes complications affecting mucous membranes and causing cell death.