A fever is an elevated body temperature, typically considered 100.4°F (38°C) or higher, indicating an abnormal process within the body. A rash represents an abnormal change in the skin’s color, appearance, or texture. When both occur together, it often raises concerns and prompts medical advice.
Understanding the Link Between Fever and Rash
While a fever rarely causes a rash directly, these two symptoms frequently occur together, indicating an underlying condition. Both are the body’s response to an internal process, such as an infection or allergic reaction. Fever signals immune system activation as the body fights off illness. The rash, rather than being a direct consequence of the fever, is a visible manifestation of the specific illness or reaction affecting the body.
Viral Infections Commonly Causing Both
Several viral infections commonly present with both fever and a rash, particularly in children.
Roseola, caused by human herpesvirus 6 and 7, begins with a high fever, followed by a pink, flat or slightly raised rash as the fever subsides.
Fifth Disease, caused by parvovirus B19, starts with mild fever and flu-like symptoms, with a characteristic bright red “slapped cheek” rash on the face, sometimes followed by a lacy rash on the body.
Chickenpox, caused by the varicella-zoster virus, presents with an itchy, blister-like rash that progresses from small red bumps to fluid-filled blisters, which then crust over.
Measles, a highly contagious viral infection, causes a high fever, cough, runny nose, and red eyes, followed by a red, blotchy rash that starts on the face and spreads downwards. Koplik spots, tiny white spots, may also appear inside the mouth before the rash.
Hand-Foot-and-Mouth Disease, commonly caused by coxsackievirus, features a fever along with painful sores in the mouth and a rash of red spots, sometimes with blisters, on the palms of the hands, soles of the feet, and sometimes the buttocks.
Other Medical Conditions Presenting With Fever and Rash
Beyond viral infections, other medical conditions can cause a combination of fever and rash. Bacterial infections are common causes.
Scarlet fever, caused by Group A Streptococcus bacteria, presents with a high fever and a distinctive red rash that feels rough like sandpaper. The rash starts on the neck and chest, spreading across the body. The tongue may appear red and bumpy, known as “strawberry tongue.”
Meningococcal disease, a severe bacterial infection, causes fever and a non-blanching rash (petechiae or purpura). These small red or purple spots do not fade when pressed, indicating bleeding under the skin and warranting immediate medical attention.
Drug reactions can cause fever and rash. These reactions are often allergic responses to medications, manifesting as hives or widespread redness. The rash can appear immediately or several days to weeks after starting a new medication.
Some inflammatory conditions, such as Kawasaki disease, also cause fever and a rash. Kawasaki disease primarily affects children, involving blood vessel inflammation. It is characterized by a high fever lasting five days or more, along with a rash, swollen hands and feet, and red eyes and tongue.
When to Consult a Doctor
Consult a doctor whenever a fever accompanies a rash, especially in children. Certain symptoms are “red flags” and require immediate medical attention. These include a rash that does not fade when pressed, difficulty breathing, a stiff neck, severe headache, confusion, or signs of dehydration. A very high fever in infants younger than three months, or if the child appears unusually ill or drowsy, also requires prompt medical evaluation.