What Is Blanching of the Skin?

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Blanching of the skin is when whitish coloration of the skin remains longer than normal after pressure is applied on an area of the skin. This occurs because normal blood flow to a given area (where blanching is being tested) does not return promptly.

Blanching is considered a physiologic test. When blanching of the fingers occurs, it could be a telltale sign of a condition called Raynaud’s syndrome. But there are several other reasons that a person may experience blanching.

dermatologist examining skin

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Blanching Test

A blanching test can be performed without any type of diagnostic tool. A physician presses the fingertips against the skin, exerting mild pressure for a short period, then quickly withdraws them, to check and see if whitening occurs.

Blanching can be tested by following a few simple steps including:

  1. Press on the skin with your fingertips (select any suspicious areas, such as a red, darkened, or pink area)
  2. The area should turn white when pressure is applied
  3. Remove the pressure from your fingertips
  4. Within a few seconds (after your fingertips are removed) the area should return to its original color (indicating that the blood flow to that specific area is good)

What Is Diascopy?

Diascopy is slightly more of an advanced technique to check skin blanching (compared to using the fingertips). This method of checking the blood flow to an area of the skin involves several steps, including:

  1. Placing a piece of clear glass (such as a glass slide for a microscope) or clear plastic against the skin to view whether the skin blanches and fills properly under pressure
  2. Pressing on the glass with the fingertips and viewing the color of the skin under pressure
  3. Withdrawing the fingers
  4. Checking to see if blanching occurs (note, blanching occurs when the area that has pressure placed on it turns whitish-colored but does not return to its original color (such as the surrounding tissue)

Signs and Symptoms of Blanching

The signs and symptoms of blanching include:

  • The skin appears white (or not as reddened) when pressure is applied
  • The whitish color that appears when pressure is applied to the skin does not return to normal within a few seconds of removal of the pressure
  • Often the skin appears cooler than normal if blood flow is occluded
  • Bluish discoloration of the skin may be present if blood flow is severely occluded
  • Numbness or pain to the affected area

Causes of Blanching

There are several reasons that blanching occurs, from simple to more complex, these include:

  • Spider veins: Small damaged or “broken” blood vessels that often appear on the surface of a person’s legs or face; spider veins are not painful, they occur in a variety of disorders (such as rosacea, liver disease, sun-damaged skin, or pregnancy).
  • Inflammation of the skin: This could include drug eruptions, hives, and more.
  • Obstruction of blood flow to an area of the skin: Chemicals, cold, trauma, radiation, or chronic conditions can impair blood flow.
  • Pressure sores: Skin abnormalities caused by unrelieved pressure, such as lying in the same position for extended periods.
  • Frostbite: A condition caused by exposure to cold external temperatures in which there is a resulting loss of blood flow to the affected area.
  • Raynaud’s syndrome: A condition that impacts approximately one-third of the people who have lupus (a condition that involves inflammation of the skin). It involves spasmodic constriction of the arteries and subsequent loss of adequate blood flow that usually affects the blood flow at the end of the fingers and toes.
  • Bier's spots: Small, irregular, hypopigmented macules that are usually found on the arms and legs.
  • Livedo reticularis: A particular kind of skin discoloration, consisting of a reddish-purplish, web-like pattern that forms circles, typically on the legs or arms.

Blanching and Darker Skin

Blanching may be harder to see on those with darker skin, so it’s vital to assess other signs that may indicate a lack of proper blood perfusion, such as the temperature and sensation of the skin.

When To See a Doctor

There are some circumstances in which blanching of the skin is severe enough that a medical professional should be consulted. Call your doctor when:

  • Skin ulcers are visible on the area of the skin that is blanched (particularly when the toes or fingertips are affected)
  • You have severe pain and blanching of the skin
  • You have any symptoms of anaphylaxis

Treatment

The treatment of blanching skin will vary greatly, depending on the underlying cause. Examples of types of treatment for blanching may include:

  • Spider veins: Treatment may involve a procedure called sclerotherapy (an injection into the veins of a solution that closes the spider veins). 
  • Raynaud’s syndrome: Treatment includes:
  • Keeping hand warmers for winter use
  • Avoiding cigarettes and caffeinated foods and beverages—which can worsen symptoms
  • Taking prescription medications—such as nifedipine or amlodipine—to help dilate the blood vessels
  • Pressure ulcers: There are many different treatment modalities for pressure ulcers, depending on the severity of the ulcer. Preventative measures include:
  • Frequent repositioning and walking/exercising as much as possible
  • Massage to help improve blood flow to the affected area

A Word From Verywell

Blanching of the skin is not normal. If you have blanching, but are unaware of the underlying cause, it’s important to seek medical attention. 

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  2. McKay M. Office techniques for dermatologic diagnosis. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990.

  3. Johns Hopkins Medicine. Lupus-specific skin disease and skin problems.