Child Rash: Simple Pen Trick Parents Can Use to Monitor Changes

A paediatric nurse has shared a simple pen trick parents can use to monitor whether a child’s rash is spreading, while highlighting symptoms that may need medical attention.

A rash on a child’s skin can be worrying for parents, particularly when it appears suddenly or seems to change over a short period of time. While many childhood rashes are linked to relatively common causes such as heat, irritation, allergies or viral illnesses, it is important to keep an eye on how the rash develops.

Paediatric nurse Sarah Hunstead has shared a straightforward tip that parents can use when monitoring a suspicious mark or rash. The method takes only a few seconds and involves using a skin-safe pen to outline the affected area.

The idea is simple. By drawing a border around the outside of a rash, parents can later compare the mark with the original outline and get a clearer indication of whether it has spread.

The advice was highlighted in a report published by the Irish Mirror on August 23, 2026.

How the pen trick works

If you notice a rash or red mark on your child, the first step is to observe its appearance carefully. If appropriate, a parent can use a skin-safe pen to draw a line around the outer edge of the affected area.

The outline provides a visual reference point. If the rash later extends beyond the line, it becomes easier to see that the affected area has changed.

Hunstead, who created the child and first aid education group CPR Kids, recommended the technique as a simple way of keeping track of changes. Her advice can be remembered as: outline the rash, then check it again later.

This does not diagnose the cause of a rash. Instead, it gives parents a practical way to monitor whether its size or appearance is changing.

Why monitoring a child’s rash matters

Childhood rashes can have many different causes. Some may develop because of heat, irritation, allergies or common viral infections. In many cases, a rash may settle without serious complications.

However, parents should pay attention to changes over the following hours or days. A rash that spreads, changes colour, becomes swollen or begins to blister may require further assessment.

The Irish Mirror report notes that a rash is not necessarily an indication of a serious condition, but monitoring changes can help parents recognise when further medical advice may be appropriate.

The pen technique can therefore be useful as a simple observation tool, particularly when it is difficult to remember exactly how large a rash looked earlier.

Look at the bigger picture, not just the rash

The appearance of a rash is only one part of assessing how a child is doing.

Parents should also consider whether their child has other symptoms. These can include a high temperature, breathing difficulties, unusual sleepiness, vomiting or appearing particularly unwell.

According to the information reported by the Irish Mirror, these symptoms can sometimes occur alongside infections or allergic reactions that may require medical advice.

This is why parents should avoid relying on the pen trick as a substitute for professional medical assessment. The outline can help demonstrate that a rash is changing, but it cannot explain why the change is happening.

What does the HSE say about rashes?

The Health Service Executive, or HSE, explains that a rash can appear as bumps or patches on the skin. The appearance can vary depending on skin tone, including differences in how redness appears on white skin compared with grey or brown skin.

The HSE information referenced in the report also explains that when a rash develops quickly and a person feels unwell, an infection may be involved. When someone has a rash but otherwise feels well, an allergic reaction such as urticaria, commonly known as hives, may be one possible explanation. Skin contact with an irritating substance can also cause a reaction.

Because rashes can have many causes, parents should consider the child’s overall condition rather than focusing exclusively on the skin.

When should parents seek urgent medical help?

Some symptoms associated with a rash can be signs of a more serious illness and should not be ignored.

The HSE advice cited in the report says people should seek medical attention if symptoms associated with meningitis are present. These include:

• Severe headache
• Vomiting
• High temperature
• Stiff neck
• Sensitivity to light

The report advises contacting a GP or going to an emergency department if these symptoms occur.

For parents, the key message is to take changes in a child’s health seriously, particularly when a rash appears alongside other concerning symptoms.

A useful reminder for parents

The skin-safe pen technique is useful because it is quick, inexpensive and easy to remember. Rather than relying on memory to decide whether a rash has grown, parents can create a simple visual reference and check the area again later.

It can also help parents communicate changes more clearly when speaking to a healthcare professional. If the rash has moved beyond the original outline, this may provide useful information about how it has developed.

However, parents should not wait for a rash to cross a drawn line before seeking help if their child appears seriously unwell. The child’s symptoms and overall condition should always take priority.

The safest approach is to monitor the rash, pay attention to other symptoms and seek professional advice when there is concern.

Final thoughts

A child developing a rash can understandably make parents anxious, but not every rash indicates a serious health problem. Many childhood rashes are associated with everyday causes such as heat, irritation, allergies and viral illnesses.

The simple pen trick shared by paediatric nurse Sarah Hunstead offers parents an easy way to monitor whether a rash is spreading. Drawing a border around the affected area and checking it again later can make changes easier to spot.

At the same time, the technique should only be viewed as a monitoring aid. It is not a medical test and cannot identify the cause of a rash.

Parents should seek medical advice if they are concerned about a child’s symptoms, particularly if a rash is changing rapidly or is accompanied by symptoms such as fever, breathing difficulties, vomiting, unusual sleepiness or a child appearing very unwell.

Source: Irish Mirror, report published August 23, 2026, based on comments from paediatric nurse Sarah Hunstead and information attributed to the HSE.
Disclaimer: This article is for general information only and does not constitute medical advice, diagnosis or treatment. A rash can have many different causes, and symptoms can vary between children. If you are concerned about your child’s health, contact a qualified healthcare professional or use official HSE guidance for further information.