Seeing a new rash on your child is enough to make any parent’s heart skip a beat. While changing clothes or giving a bath, you might suddenly notice spots that are not pink or red but deep purple and patchy.
Even if your child seems fine, playing and eating normally, a purple rash should be checked by a professional. Most rashes are harmless but some can indicate a serious problem that needs quick medical care.
“Purple rashes can look scary but they have many causes,” said Russell Horton, DO, a pediatrician at Banner Health. “The best thing is to have your child checked so we can find out what it is. It might only be bruises but it’s better to err on the side of caution.”
Read on to learn what a purple rash might mean, what causes it and why you should see your child’s health care provider if you are worried.
What does a purple rash mean in children?
Most rashes appear red because of increased blood flow to the skin. When blood leaks out of small blood vessels and collects under the skin, the rash appears purple.
These rashes can look like:
- Small purple or red dots
- Larger purple spots
- Bruise-like patches without any injury
Common causes of a purple rash on a child’s leg
Bumps and bruises
Sometimes, a purple rash isn’t a rash at all; it’s bruising.
“Children are active and small blood vessels can break from bumping into objects, tight clothing or socks or even from carrying heavy backpacks,” Dr. Horton said.
What to look for:
- Purple spots in areas of pressure or impact
- No other symptoms
- Fading over a few days like a bruise
Allergic reactions
Certain allergic reactions can cause changes in blood vessels that lead to a purple or blotchy rash.
Possible triggers:
- Foods
- Medications
- Insect bites
What to look for:
- Itching
- Swelling
- Hives or raised areas
Most allergic rashes are red but, in some cases, especially if blood vessels are involved, they may appear darker. See your child’s health care provider to rule out other causes. They may recommend allergy testing.
Seek emergency care if your child experiences a severe allergic reaction. Along with a rash, symptoms may include:
- Swelling of the face, lips, tongue or eyes
- Trouble breathing
- Vomiting
Viral infections
Some viral infections can cause a red or purple rash. Examples include:
- Common respiratory viruses
- Enteroviruses
- Influenza
What to look for:
- Fever
- Tiredness
- Runny nose or cough
- Rash that appears during or after illnesses
Henoch-Schönlein purpura (HSP)
Henoch-Schönlein purpura (HSP) is a type of vasculitis most commonly seen in children aged 2 to 6 years.
“Henoch-Schönlein purpura is a condition that causes inflammation in small blood vessels,” Dr. Horton said. “It often shows up as a purple rash on the lower legs or buttocks.”
What to look for:
- Rash and stomach pain
- Joint pain or swelling (knees and ankles are common)
- Swelling in the hands or feet
- Blood in urine (in some cases)
While it can be worrying, most cases are mild and will heal on their own. HSP usually happens after a cold or other respiratory illness.
However, you should have your child checked out by their health care provider, especially if they have stomach pain or swelling along with the rash. In rare cases, HSP can cause severe kidney damage or bowel blockage (intussusception).
Less common but serious causes
Severe bacterial infections: Meningococcal disease
A purple rash can sometimes signal a serious bacterial infection called meningococcal disease. This includes two related illnesses caused by the same bacteria:
- Meningococcemia: When bacteria are in the bloodstream
- Meningococcal meningitis: When the bacteria infect the lining of the brain and spinal cord
The purple rash is most often seen with meningococcemia, when the bloodstream is affected. But if meningitis occurs alongside it, the rash may appear then, too.
What to look for:
- Fever and chills
- Headache or stiff neck
- Nausea or vomiting
- Extreme tiredness or difficulty waking
- Sensitivity to light
- Rapidly spreading purple spots or bruise-like patches
This condition is a medical emergency. If your child has a purple rash and any of these symptoms, seek urgent care. Early treatment with antibiotics can save lives.
Blood or clotting disorders
Sometimes, a purple rash can be caused by low platelet counts or a blood condition. Or in rare cases, leukemia.
“Platelets help your blood to clot, so if there aren't enough it can cause easy bruising or bleeding under the skin,” Dr. Horton said. “These cases don't happen often but it's important to have your child checked by their provider.”
What to look for:
- Easy bruising
- Frequent nosebleeds
- Bleeding gums
- Fatigue or pale skin
Tick-borne illness
Some infections spread by ticks can cause a rash that darkens or turns purplish. One example is Rocky Mountain spotted fever. These infections can become serious if not treated early.
What to look for:
- Fever
- Headache
- Rash starting on wrists or ankles
- Recent outdoor exposure
When should you call your child’s provider?
Any new or unusual rash is worth paying attention to, especially if it looks purple.
Call your child’s provider if your child has a rash along with:
- Fever
- Joint pain or swelling
- Belly pain
- Bruising without injury
- The rash lasts more than a few days
- Child is less than 6 months old
The provider will examine your child and ask about symptoms. In some cases, they may order blood tests or urine tests.
When to seek emergency care
Some symptoms need immediate attention. Call 911 or go to the nearest emergency room if your child has:
- A purple rash with fever and appears very ill
- Trouble waking up or extreme sleepiness
- Stiff neck
- Difficulty breathing
- A rash that spreads quickly
- Signs of dehydration (dry mouth, no tears, fewer wet diapers)
How purple rashes are treated
Treatment depends on the cause:
- For mild conditions: If your child has a mild case of HSP or a viral rash, home care may include rest, fluids and over-the-counter (OTC) pain relief. Contact your provider if you notice new or worsening symptoms.
- For infections: Your child’s provider may prescribe antiviral or antibiotic medications.
- For serious conditions: Your child may need hospital care and specialized treatment.
The bottom line
A purple rash on your child’s legs can have several causes, from mild to more serious. While most cases do get better on their own, in rare cases they may need urgent care.
If your child has an unexplained rash, call their provider. It’s better to talk to them about a rash than to miss symptoms of a serious illness. Schedule an appointment today.
Frequently asked questions about purple rashes in children
Why is my child’s rash purple instead of red?
A purple rash often means there is bleeding under the skin rather than surface irritation. This can happen when a small blood vessel breaks or becomes inflamed. That’s why the rash may look like bruises instead of a typical red rash.
Is a purple rash always serious?
A purple rash is not always serious. Sometimes, mild infections or slight pressure on the skin can cause it and it will go away on its own. But if your child has a new or suspicious rash, see a health care provider.
Can a cold cause a purple rash?
Yes, some viral infections (including colds) can lead to a rash. In some cases, conditions like HSP can develop after a respiratory illness and cause a purple rash on the legs.
