Children’s Rashes: Red Flags to Know, When to Worry & When to Act

Rashes are one of the most common reasons parents feel unsure, anxious, and stuck between “this is probably fine” and “do we need to get this checked… now?”

And here’s the truth: most childhood rashes are harmless, short-lived, and part of growing up. But some rashes — especially when paired with other symptoms — can be signs of a child who is becoming unwell.

This is where The Sick Sense comes in.

It's not about naming the rash perfectly — it’s about recognising when a rash matters.

First Things First: Rashes Are Common

Children’s skin is sensitive and reactive. Rashes can appear due to:

• Viral illnesses

• Bacterial infections

• Allergic reactions

• Heat, sweat, and friction

• New foods, soaps, detergents, or clothing

• Insect bites

Many rashes come and go without treatment and without causing harm. The rash itself is only one piece of the puzzle.

The Sick Sense Rule: Don’t Look at the Rash in Isolation

When assessing a rash, parents often zoom in on:

• Colour

• Shape

• Location

Clinically, what matters just as much — if not more — is how your child is behaving and interacting overall.

Zoom out and look at the whole child — ask yourself:

• How does my child look?

• Are there any other Red Flags or cause of concern?

• How do they seem?

• Are there other symptoms alongside the rash?

  
  

Common Childhood Rashes (Usually Mild)

These rashes often look dramatic but are usually self-limiting:

• Viral rashes (often pink or red, widespread)

• Heat rash

• Eczema flares

• Mild allergic rashes such as hives

Children with these rashes are often:

• Alert

• Drinking reasonably well

• Still interacting

• Improving over time

  
  

Rashes of Concern: Red Flags Parents Should Know

Some rashes need urgent medical review, especially when paired with signs of deterioration.

Non-Blanching Rash — The Sick Sense Explanation

A non-blanching rash is what we at the Sick Sense call an unsafe rash.

It is unsafe because there is no blood flow returning to that area of skin. When you press on it, the rash does not fade — meaning the blood underneath is not moving as it should. This can be associated with serious illness and always requires urgent medical assessment, particularly if your child appears unwell.

This is very different from a blanching rash, which we consider a safer rash. A blanching rash will fade when you press on it, then return once you let go — showing that blood flow is still present at the skin’s surface.

While we still want medical review for blanching rashes, this is where Sick Sense helps guide urgency.

If we look at the entire picture of the child — they are alert, responsive, drinking, and otherwise well — this may not be a situation where you need to drop everything and race to Emergency at 2am during a nappy change.

Instead, this can be a moment to:

• Continue regular assessment

• Monitor for any changes

• Book an online GP appointment for the morning

• Escalate if new red flags appear

  
  

The key difference is urgency, not importance.

Non-blanching rash = urgent escalation

Blanching rash + well child = monitor, assess, plan

Rash with Fever and Behaviour Change

Be concerned if a rash appears alongside:

• Lethargy or excessive sleepiness

• Inconsolable crying

• Reduced responsiveness

• Poor feeding or drinking

The combination matters more than the rash alone.

Rapidly Spreading or Worsening Rash

A rash that:

• Appears suddenly

• Spreads quickly

• Becomes painful, blistered, purple, or bruised-looking

…should be reviewed promptly.

Rash with Breathing, Swelling, or Vomiting

If a rash is accompanied by:

• Lip, tongue, or facial swelling

• Breathing difficulty

• Persistent vomiting

This may indicate a severe allergic reaction and needs urgent medical care.

When to Escalate Care

Seek medical advice or urgent assessment if your child:

• Has a non-blanching rash

• Has a rash with fever and appears unwell

• Is lethargic, floppy, or hard to wake

• Has a rash with breathing issues or swelling

• Has a rash that is rapidly worsening

• Is under 6 months old with a rash and fever

Trust your instincts. If something feels off, it usually is.

The Sick Sense Take-Home

You don’t need to diagnose the rash.

What you do need to recognise is:

• Is it a 'safe' or 'unsafe' rash

• Are my child's symptoms improving or worsening?

• Do I need to escalate and advocate?

Rashes are common. Deterioration is not.

Your job isn’t to Google every rash — it’s to notice the whole child.

That’s Sick Sense.

Want to Know More?

Join our next face-to-face Baby & Child First Aid Workshop, or jump into The Sick Sense Bite-Sized Online Course.

Practical, parent-friendly education with 24/7 access — straight in your back pocket.

Important Disclaimer

The information shared in this blog is for general education only and does not replace individual medical advice. If you are concerned about your child, notice red flags, or feel something isn’t right, seek advice from your GP, local health service, or emergency services. Parents know their children best — trust your instincts.