What Is a Mono Rash?

A mono rash is typically a red, blotchy rash that appears on the chest and back of people with mononucleosis, an infectious disease most often caused by the Epstein-Barr virus (EBV). A rash may occur because of mono itself or in response to medications used to treat it.

A mono rash can vary from one person to the next, both in its appearance and accompanying symptoms. The rashes may be raised or flat, widespread or localized, or itchy or non-itchy.

This article describes what a mono rash can look like, the potential causes, and how an outbreak may be diagnosed and treated.

What Is a Mononucleosis Rash?

A mono rash may look different in different people. It can appear as a maculopapular or morbilliform (measles-like) rash, petechiae (brown-purple spots), or urticaria (hives).

Maculopapular or Morbilliform

A maculopapular or morbilliform rash appears as flat spots on the skin that are pinkish red. This type of rash typically starts on the face and behind the ears, but can spread down to the neck and chest, and eventually across the entire body. In some cases, it may also present with raised lesions, or abnormal tissues, that are also pinkish red.

Hives

Hives appear as welts on the skin that could be either the same color as the skin or red. The size of the spots varies. They can be small and round or large and asymmetrical. The spots are extremely itchy and tend to pop up in one area on the body.

Petechiae

Petechiae, a rash that appears as small, almost pinpoint, rounded dos, can also develop due to mono. The dots are usually reddish purple.

In some types of rashes that look like petechiae, the dots will become pale or white if you apply pressure to them. However, in the case of petechiae, their color does not change when you press them. This type of rash most commonly affects the roof of the mouth.

What Causes a Mono Rash?

A mono rash could be a result of the virus itself or the use of antibiotics.

Maculopapular or Morbilliform

The maculopapular or morbilliform rash that occurs in mono can be caused by the viral infection itself or the use of antibiotics such as amoxicillin or ampicillin.

Antibiotics aren’t typically given for viral infections like mono. However, the infection can mimic other conditions, such as strep throat, which is treated with antibiotics.

Those who develop this type of rash are not allergic to the medication. It’s also unlikely that the rash will develop in the future if they take the same type of antibiotics for another type of infection.

It is unclear why antibiotic use causes a mono rash, but some researchers believe it could be because the virus causes a loss of drug tolerance.

Without antibiotics, a rash occurs in roughly 4% to 13% of people with mono. With antibiotics, a mono rash develops in 27% to 69% of people. In children with mono, taking antibiotics almost always leads to a rash.

Hives

The mechanism behind why hives develop in people with mono is not clear, but it’s thought that the viral infection could be a trigger.

Petechiae

A petechiae mono rash is usually brought on by the virus itself. The dots are caused by the bleeding that occurs in the skin from broken capillaries. Roughly 50% of people with mono will experience this type of rash.

How Mono Is Diagnosed

Mono can be difficult to diagnose because of nonspecific symptoms and the fact that its symptoms are similar to those of many other conditions. Besides a rash, symptoms of mono can include:

• Extreme fatigue
• Fever
• Sore throat
• Headaches
• Body aches
• Swollen lymph nodes in the neck or under the arms
• Swollen liver or spleen

These symptoms often occur in other types of illnesses, such as strep throat, chronic fatigue, and other types of viral infections.

Blood Tests

To diagnose mono, a healthcare provider will take your medical history and record all the symptoms you have. They can usually make a diagnosis based on these two pieces of information.

Your healthcare provider may also order different types of blood tests. In those who have EBV, their bloodwork will indicate the following:

• Higher amount of white blood cells (immune cells)
• White blood cells that are unusual in appearance
• Lower level of neutrophils (a type of white blood cell) or platelets (blood cells responsible for blood clotting)
• Abnormal liver function

They may also order tests that look for antibodies, including the EBV antibody test which looks for antibodies created specifically to fight off the Epstein-Barr virus. A monospot test will look for antibodies, called heterophile antibodies, which the body creates to fight off mono and other infections.

How Mono Rashes Are Treated

There is no cure or treatment specifically designed to fight off mono. Typically, people with mono will recover with rest, fluids, and over-the-counter symptom relievers such as lozenges or pain medications.

A mono rash usually clears up on its own as the body recovers from the viral infection. The extent and duration of the rash will depend on the cause. If it is caused by antibiotics, the rash should clear up within one week of stopping the antibiotics. However, it can take roughly three months for the rash to disappear completely.

In the event that the rash is causing uncomfortable itchiness, prescription or over-the-counter antihistamines and topical steroids can help relieve the symptom while the rash heals.

Summary

A mono rash is a symptom that can appear in some people with the viral infection. It can take several forms, and each is associated with a different cause. As with the infection, the way to treat your mono rash is to get lots of rest, fluid, and let your body recover.

A Word From Verywell

Mono is an incredibly common viral infection. Although the symptoms can be difficult to cope with, they will clear up on their own with lots of rest. A mono rash may be unsightly or bothersome, but it will also dissipate once you recover from the infection.

In the event that your rash is a result of taking antibiotics, you should speak to your healthcare provider. It’s likely they were unaware that mono was causing your symptoms, and they may advise you to stop taking the medication. Once this happens, the rash will begin to clear up.