Understanding common pediatric infectious diseases is essential for effective care. Chickenpox, caused by the varicella-zoster virus, is highly contagious and preventable through vaccination. It spreads via airborne transmission and direct contact, leading to fever, muscle aches, and an itchy vesicular rash. Fifth disease, or erythema infectiosum, results from parvovirus B19 and presents with fever followed by a distinctive “slapped cheek” rash. Roseola, caused by human herpesvirus 6, is marked by high fever and a maculopapular rash starting on the trunk. Supportive treatment includes acetaminophen or NSAIDs, while aspirin should be avoided.