How Do I Recognize a Measles Rash?

A rash is usually just one of the many symptoms of measles, and recognizing it is often as much about seeing all the symptoms in sum as it is about identifying particular characteristics. All people, and especially children, develop rashes for a range of reasons, some more serious than others. In most cases the most distinguishing characteristic of a measles rash is that it appears a few days after other measles symptoms, particularly a sustained spiked fever; a cough, often paired with a runny nose; and itchy, watery eyes. The rash itself normally begins at the scalp or on the face, and normally presents as small red bumps at first. These have a tendency to spread, and within a few days — and in some cases in as little as a few hours — the bumps will grow and spread to cover the neck, chest, and torso, and will normally extend down the arms and legs as well. In general anyone who suspects that a rash is related to measles is advised to seek prompt medical care, both to speed recovery and to prevent spread of the disease to others as measles is highly contagious.

Measles is typically a childhood illness caused by the morbillivirus that lives in the mouth and nose of infected children. The virus is released into the air when the child coughs or sneezes and, as such, is highly contagious. The incubation period, which is to say, the time between a person being exposed to the virus and developing symptoms, is normally anywhere from 10 to 14 days. Although outbreaks are less common in most places today as a result of widespread vaccination programs, they still happen, and those who have not been vaccinated, a class which includes most infants, are at particular risk.

Complications from measles include pneumonia and encephalitis and can be quite serious. Knowing the symptoms, including recognizing the rash, can be very important tools when it comes to getting prompt treatment. In many cases there is no specific treatment aside from letting the illness run its course and making sure the patient is taking in adequate fluids. Most adults and older children will make a full recovery, but the same isn’t always true for the very young; in children under the age of 5, the illness is often fatal, particularly if it develops into something else. In these cases prompt hospitalization is usually crucial.

A rash usually starts appearing about two weeks after a patient has been exposed to the virus. One of the earliest indications of measles is usually the development of Koplik spots, tiny blue-white dots surrounded by red inside the mouth and on the insides of the cheeks. These spots are often thought to be the true beginnings of the rash, or at least a precursor to it. Flat red bumps typically start appearing on the skin near the ears and at the hairline about the time the Koplik spots are fading.

From one to two days after the rash first appears near the hairline, it may spread to the torso and limbs, even as it starts to disappear from the face. The measles rash can be mildly itchy. The patient is generally infectious from a few days prior to the rash's appearance until a few days after, and it is at this point that the rash also begins fading.

It’s important to realize that a rash is not the first sign of measles, or even the best way to diagnose the illness. Patients normally feel unwell for several days before the rash ever appears; most have a very high temperature paired with a runny nose, a cough, and usually also watery eyes. A rash can confirm suspicions of measles, but isn’t usually itself enough to make a diagnosis.

A related illness known as German measles, caused by the Rubella virus, is contracted the same way as the more standard measles virus and has an incubation period from 12 to 23 days. When it comes to diagnosing German measles, one of the most reliable symptoms is the swollen lymph glands around the hairline, behind the ears. A child with German measles will also have a sore throat, runny nose, a slight fever and a rash. A German measles rash involves small pink dots that rapidly spread over the body, especially the torso. Although this rash resembles the measles rash, there is less of it and in most cases it goes away faster.