Scarlet fever

What is scarlet fever?

Scarlet fever is a bacterial infection that causes a characteristic red rash. It’s most common in children between the ages of 5 and 15. It used to be considered serious, but nowadays it’s easy to treat with antibiotics and complications are rare.

What are the symptoms of scarlet fever?

Some of the first symptoms of a scarlet fever infection are:

• A high temperature (38.3 °C or above)

• Headache

• Fatigue

• Nausea and vomiting

• Sore throat

A scarlet fever rash usually appears around 2 days after getting the infection. This is typically a pink-red colour, and has a rough texture like sandpaper, starting on the trunk and spreading all over the body. The rash tends to fade after about a week. If you’re infected you may also get a ‘strawberry tongue’, which starts off with a white coating and then disappears to reveal a red and bumpy tongue.

Scarlet fever in adults presents with the same symptoms as in children.

Scarlet fever incubation period

The incubation period of an infection is the time between coming into contact with the disease and developing symptoms. For scarlet fever, the incubation period is around 2 to 5 days, but this can vary and you may be infectious for up to 6 days longer before you start showing any symptoms.

What causes scarlet fever?

Scarlet fever is caused by group A streptococcus bacteria. These bacteria release toxins which cause the red rash and strawberry tongue in scarlet fever. 

Children who have recently had a throat or skin infection caused by the same streptococcus bacteria, like impetigo, may go on to develop scarlet fever.

How is scarlet fever diagnosed?

A healthcare professional can usually make a diagnosis by asking about your symptoms and by taking your temperature then looking at your tongue and rash. It may be necessary to swab the back of your throat to check which bacteria has caused the infection and confirm the diagnosis.

How is scarlet fever treated?

Scarlet fever can be treated using antibiotics prescribed by a healthcare professional. Usually they will prescribe penicillin, or azithromycin if you’re allergic to penicillin.

It’s important that you finish the full course of antibiotics to make sure that the infection is completely gone, and to reduce the risk of complications.

You or your child should make sure that you rest and continue to drink plenty of fluids. You can also take pain relief, such as paracetamol or ibuprofen, to manage your symptoms. Calamine lotion can be applied to soothe itchy skin.

When should I seek help?

You should speak to a healthcare professional straight away if you or your child have symptoms of scarlet fever, so a course of antibiotics can be started as soon as possible. The healthcare professional may prefer to speak to you over the phone or video call to prevent the spread of the infection. If your symptoms continue a week after seeing a healthcare professional, let them know.

If your child becomes very unwell, or shows any of these signs, you should call 999 or go to A&E:

• Difficulty breathing

• Developing a rash that does not disappear when pressure is applied

• Going blue around the lips

• Pale, cold and blotchy skin

• Becoming lethargic or confused

• Having a seizure

• Having a temperature above 38 °C if your child is under 3 months old