Skin Blanching: The Social Media Hack Experts Don’t Love

Blanching of the skin can cause more panic than necessary according to one expert.

Young boy with varicella zoster virus
Photo: Getty

Social media is full of skin and parenting hacks. The latest trend combines the two. It's called skin blanching, and users swear it helps diagnose the severity of a rash and whether or not it requires medical attention.

In one video, the user rolls a cup over a child's rash and says it's life-threatening. It sounds like a life-saving trick, and you may wish you had known about it years ago.

But it's always a good idea to approach parenting and wellness tricks found on social media with a healthy dose of skepticism. Does this trending DIY test really check out?

The short answer is no, according to Elaine F. Kung, M.D., a clinical assistant professor at Weill-Cornell Medical College and dermatologist at Future Bright Dermatology. Kung explained more about blanching of the skin and why she doesn't recommend it as a diagnostic tool for parents.

What Does 'Blanching Skin' Mean?

Kung says the first step in understanding why rashes appear discolored. It's important to note that the color will depend on the skin tone. A rash may appear red on lighter skin, whereas it can look off-white, brown, or black on darker tones.

Kung says this discoloration "occurs when there is inflammation in the skin and dilation of blood vessels increases blood flow in the area."

What does all of this have to do with skin blanching?

"The rash is considered 'blanchable' when the [discoloration] disappears when we apply pressure on the rash," Kung says. "The pressure temporarily stopped the blood flow into the area."

If the discoloration does not disappear, the skin is non-blanchable.

"Nonblanchable rashes are the results of damaged blood vessels leaking blood into the skin," Kung says."

Pressure can be applied with your fingers, though medical professionals use a glass slide—hence, the cup in the Instagram video.

What Do the Results Mean?

Is one type of rash—blanching or non-blanching—more dangerous? Not necessarily. That said, Kung knows the idea of blood leaking into the skin can sound alarming.

"There are plenty of nonblanchable…patches that are not serious at all," Kung says. "For example, a port-wine stain is a type of birthmark that is nonblanchable."

But some nonblanchable rashes do require medical treatment. Kung says a few serious conditions that may include nonblanchable rashes are:

  • Kawasaki disease
  • Rocky Mountain Spotted Fever
  • Sepsis autoimmune vasculitis
  • Leukemia

Blanchable rashes can also be benign and due to lack of circulation or bug bites. But they can also be a sign of something more serious. Kung says blanchable rashes can be a symptom of:

  • Drug reactions
  • Lyme disease
  • Staphylococcal

In other words, the rash type is a symptom, not a diagnosis, and blanching and nonblanching rashes can signal conditions that vary in severity. Doctors will also look at other symptoms, such as a fever, muscle ache, cough, diarrhea, and extreme fatigue, when treating patients.

Bottom Line: You Can Skip This Trend

As you can see, there's a wide range of issues, and some sound scary. It's understandable you want answers and fast. But, hard as it is, Kung says it's best to try not to panic, avoid using blanching to self-diagnose and call a doctor.

"I would caution parents in DIY diagnosis based on social media tutorials," Kung says. "Blanching skin rashes is not a reliable predictor of whether your child needs medical attention."

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