Slapped cheek syndrome

Also called Fifth disease, Parvovirus B19, Erythema infectiosum

A mild childhood rash that matters for three groups: pregnant women, people with sickle cell, and anybody immunosuppressed.

What it is

A common childhood infection caused by parvovirus B19, producing a bright red rash on the cheeks followed by a lacy rash on the body.

In healthy children it is mild and needs nothing. **The important point is that the child is infectious before the rash appears and not once it has.** By the time the cheeks are red the risk to others has passed, which is why exclusion from school is pointless and not recommended.

Three groups matter, and they are the reason this entry exists.

**Pregnancy.** Infection before 20 weeks carries a small risk of miscarriage and of fetal anaemia and hydrops, which is treatable with intrauterine transfusion if detected. A pregnant woman exposed to it, or developing a rash, should tell her midwife and have blood tests for immunity, since around half of adults are already immune.

**Sickle cell disease, thalassaemia and other conditions with a short red cell lifespan.** The virus temporarily stops red cell production, causing an aplastic crisis with sudden severe anaemia. This is a medical emergency. See sickle cell disease.

**Immunosuppressed people**, who can develop persistent infection and chronic anaemia.

In adults, particularly women, it commonly causes painful joints lasting weeks and is often mistaken for early rheumatoid arthritis.

Signs you might notice

A few days of mild fever, headache and cold-like symptoms.

Then a bright red rash on both cheeks, like a slap mark, most obvious on lighter skin and harder to see on brown and black skin.

A few days later, a lacy or blotchy rash on the arms, trunk and legs, which can come and go for weeks, reappearing with heat, sunlight and exercise.

In adults: painful, swollen joints, particularly hands, wrists, knees and ankles, lasting weeks.

Urgent: sudden pallor, breathlessness, extreme tiredness or collapse in somebody with sickle cell disease or another blood condition, which suggests aplastic crisis.

Also: exposure or rash in pregnancy, which needs blood tests; and infection in anybody immunosuppressed.

Not this: a rash with fever that does not fade under a glass, which needs immediate assessment for meningitis.

How it can affect day-to-day life

Because the child is no longer infectious once the rash appears, keeping them off school achieves nothing and costs families a great deal. This is worth saying clearly, because the instinct is the opposite.

The lacy body rash recurs for weeks with heat, baths, sunlight and exercise, and parents frequently return to the GP thinking it is a new illness.

Outbreaks in schools and nurseries are common in spring, and the useful action is telling pregnant staff and parents so they can seek advice, rather than excluding children.

In pregnancy the message is not panic but blood tests: most women are immune, and where infection is confirmed, monitoring with ultrasound detects the treatable complication.

For families affected by sickle cell disease, knowing about this virus specifically is part of routine education, and a sudden drop in energy and colour after a viral illness needs urgent blood tests.

Adults with the joint symptoms are frequently investigated for inflammatory arthritis, and asking about recent contact with children with a rash saves a lot of that.

Supporting someone well

Do not keep a child off school; they are no longer infectious once the rash appears.

Expect the body rash to come and go for weeks with heat and sunlight.

Use paracetamol or ibuprofen for fever and aches, and fluids.

Tell pregnant contacts, so they can get blood tests for immunity.

In pregnancy, contact the midwife about exposure or a rash; do not wait.

For anybody with sickle cell disease or thalassaemia, treat sudden pallor and tiredness as an emergency.

Tell any immunosuppressed contact.

In an adult with new joint pains, mention recent contact with a child with a rash.

Get any non-fading rash with fever assessed immediately.

Where to get help

A GP practice or NHS 111 for advice; most children need nothing.

A midwife or maternity unit for exposure or rash in pregnancy.

The haematology team urgently for anybody with sickle cell disease or thalassaemia.

Sickle Cell Society and UK Thalassaemia Society for the specific risks.