Éruptions virales

What is a viral rash?

The symptoms caused by viral infections can vary depending upon the virus. One of the symptoms that may occur is a rash. There are some well-known viral rashes.

For example, the measles virus and the virus de la varicelle cause characteristic rashes along with other symptoms. Sometimes a typical rash helps a doctor to diagnose which virus is causing an illness.

Rougeole

© CDC/NIP/Barbara Rice, Public domain, via Wikimedia Commons

Other viral rashes include:

• Rubella (German measles).

  Rubéole

  

  © Photo Credit:Content Providers(s): CDC, Public domain, via Wikimedia Commons

• fièvre glandulaire.

• Zona.

  Zona

  

  © Fisle, CC BY-SA 3.0, via Wikimedia Commons

• Hand, foot, and mouth disease.

  Maladie main-pied-bouche

  

  © KlatschmohnAcker, CC BY-SA 3.0, via Wikimedia Commons

• Fifth disease (slapped cheek disease).

  Slapped cheek

  

  © Gzzz, CC BY-SA 4.0, via Wikimedia Commons

• Roséole.

  Roséole

  

  © CNX OpenStax, CC BY 4.0, via Wikimedia Commons

• Chickenpox.

  Child with chickenpox

  

  © CC BY-SA 3.0

For those who have recently travelled abroad, there are many other possible causes of a viral rash, including those transmitted by mosquitos, eg, West Nile virus, Virus Zika, and la dengue.

Many viruses can cause a rash in addition to other symptoms such as high temperature (fever) and cough. Many of these rashes are 'nonspecific'. This means the rash is not specific or characteristic enough to identify the virus that is causing the rash.

The doctor cannot say which virus is the culprit, but can say that some virus is a likely cause of the rash.

What do viral rashes look like?

Viral rashes vary in shape and size. However, they often appear as blotchy red spots. Commonly they affect most of your body.

Sometimes they appear dramatically. For example, you may wake up in the morning to find yourself covered in a rash.

How long do they last?

It usually lasts only a few days. Sometimes the rash is slightly itchy. Usually the rash disappears without trace within a few days. There is a great variety of types.

Conditions mistaken for a viral rash

Some skin conditions, such as eczéma ou l'urticaire, can cause rashes that look similar to a viral rash.

Most viral rashes are not serious. They clear up on their own without any treatment. However, rashes may much less often be caused by serious virus infections such as HIV and those transmitted by mosquitos when travelling abroad.

Therefore, it is very important to make sure the rash is not part of a serious virus infection, or any other serious cause, such as meningococcal infection, which is caused by a bacterial infection.

Other signs suggestive of meningococcal infection in babies and young children include becoming floppy and unresponsive, unusual crying, being very sleepy and having a very high temperature (fever).

The rash of meningococcal infection is usually purple or red spots that don't fade when put under pressure (for example, by pressing a clear glass against your skin).

Glass test for meningitis rash

What matters is whether other symptoms or problems occur. For example, the measles virus can cause a nasty illness with a chest infection, severe diarrhée, etc, in addition to a rash.

However, many viruses cause only minor symptoms - perhaps a mild fever or slight cough - but the rash may look quite dramatic. Sometimes the rash appears just as the other symptoms are improving.

Viral rashes and pregnant women

Most viral infections causing a rash will do no harm to your developing baby. However, some may do. For example, the rubella (German measles) virus et varicelle. In particular, if you catch chickenpox in pregnancy and have not had it before, you should seek advice from your midwife urgently (usually via the maternity day unit), as you may need treatment to protect your baby.

It is therefore often best for pregnant women to avoid people who have an infectious rash. Also, if you are pregnant and develop a rash, it is advisable to see a doctor for advice.

The sudden appearance of a widespread blotchy rash is quite common. It is often due to a viral infection. It is the other symptoms that may be of more concern. If other symptoms are mild then there is usually little to worry about. It will usually go in a few days.

There is no specific treatment for the rash itself. Treatment should be aimed at the other symptoms. For example, paracétamol can be used for a high temperature (fever). Some conditions which cause a rash, such as measles, can be extremely dangerous and cause severe illness and death. It is therefore very important to be vaccinated against these conditions - vaccinations are safe and do not cause autism.

Rashes that are itchy often respond to an antihistamine tablet which can be obtained from your doctor or a chemist. There are also various creams available which can work to reduce itching.

When to see a doctor or nurse about viral rashes

If you have any concerns then you should contact a doctor immediately. It’s always a good idea to talk with a healthcare professional when you notice a new rash. It is important to make an appointment if:

• You feel generally unwell or feverish.

• The rash lasts longer than a week, especially if it doesn’t seem to be improving.

• The rash starts to blister.

• The rash spreads rapidly or is all over your body.

• The rash shows signs of redness, swelling, and oozing.

• The rash is painful.

• The are any concerns that the rash may indicate a serious illness.