Not all rashes require treatment but it is important to provide parents with a diagnosis. “Parents are disproportionally concerned about rashes,” she said. Whenever possible, reassure parents when a rash is self-limiting, but let them know that some rashes can go on for weeks.

When seeing any pruritic rash, consider scabies. The entire family will likely need to be treated with permethrin, ivermectin, or lindane. Although permethrin is a first-line treatment for scabies, Dr. Rose noted that there is a strain of permethrin-resistant scabies.

The biggest mimicker she sees is impetigo. “Consider this diagnosis any time you see a rash that’s spreading among kids,” she said. “I have seen many weird presentations of impetigo.”

One particularly dangerous rash is sepsis peritonitis necrotizing fasciitis, especially in a neonate losing his or her umbilical stump. The child will need IV antibiotics and admission to the hospital.

Any necrotizing fasciitis can be so sneaky, said Dr. Rose. Consider a diagnosis any time you see a rash with muscular-skeletal complaint, especially when the pain is out of proportion to the rash. “Although the LRINEC score is imperfect, use it,” she said.

Another tricky diagnosis is henoch schonlein purpura. “This is purely a clinical diagnosis,” she said. “There is no confirmatory lab tests. Gastrointestinal pain may be the only symptom.” Dr. Rose warned that these patients could easily develop renal disease. Steroids can decrease abdominal pain, but do not impact outcome.

Some rashes may be the result of infections or drug interactions. Stevens-Johnson syndrome is a medical emergency that requires hospitalization. More than 90 percent of the cases will involve two or more mucous membranes. If this syndrome is suspected, immediately discontinue all non-essential medications and provide wound care.

Kawasaki disease presents in two phases characterized by a fever lasting five days and rash. “Anytime you have a rash and fever, consider Kawasaki,” Dr. Rose said. The bad news is that there is now an atypical or incomplete Kawasaki disease that involves a fever that lasts less than five days. “Know that this exists,” she said. “Kids tend to get it as infants. They are the ones who have long-term complications, including cardiac complications. It’s important for us to make the diagnosis.”

Speaking about anaphylaxis, Dr. Rose said that 20 percent of the cases present without a rash. “Don’t waste your time with anything else—epinephrine is the treatment,” she said.

She concluded by encouraging physicians to consider the common causes of rashes first. “You are much more likely to see an atypical presentation of a common rash than a zebra,” she warned.