EczemaPatient friendly summary

  • UVB light appears to reduce the risk of eczema and atopic dermatitis by producing vitamin D and reducing inflammation.
  • Vitamin D may reduce the risk of eczema and atopic dermatitis by producing cathelicidin, an antimicrobial protein.

Eczema is a group of conditions that cause skin inflammation or irritation.

The most common type of eczema is atopic dermatitis (AD) or atopic eczema. Atopic refers to the inherited tendency to develop allergies. People with atopic dermatitis may also have asthma and hay fever.

In the United States, 11% of people below 18 years of age may have eczema.

Risk factors

The causes of eczema are not well known. Both genetics and environment contribute to risk. In the United States, increased risk is noted in:

  • People who live in major cities
  • African-Americans
  • People who live with their college-educated parents
  • Asthma
  • Fungi in bedroom

Sunlight exposure and eczema and atopic dermatitis risk

There are few studies of eczema and sunlight exposure. One Australian study found lower rates of eczema at higher latitudes. Higher latitudes are farther from the equator and have less ultraviolet-B (UVB) light. Sunlight may lower some of the inflammation associated with atopic dermatitis.

Vitamin D and eczema and atopic dermatitis 

Vitamin D levels

There is mixed evidence that vitamin D benefits eczema:

  • In Italy, the severity of AD increased as vitamin D levels decreased. These results pertain to the condition of eczema, not the risk of developing the disorder.
  • Researchers in Finland studied people who regularly took vitamin D supplements in infancy. At age 31 years of age, those studied had a 30% increased risk of AD and a similar risk for asthma.
  • Swedish children 6 years of age and younger who took 520 international units (IU) [13 mcg]/day of vitamin D3 (cholecalciferol) to those who took less than that.

How vitamin D works

UVB light can produce vitamin D in the skin. Vitamin D then produces cathelicidin and defensins, antimicrobial proteins. Cathelicidin is suppressed during AD. Therefore, a person with atopic dermatitis benefits from cathelicidin produced by vitamin D.


It is not clear whether vitamin D can prevent eczema and atopic dermatitis.


Heliotherapy is controlled therapeutic exposure to sunlight. It has been used to treat eczema as early as 1964.

Two studies show positive effects of sunlight on atopic dermatitis:

  • People from Finland with atopic dermatitis traveled to the sunny Canary Islands during the winter. The Canary Islands are farther south than Finland and have more UVB light. After a two-week heliotherapy course, vitamin D levels increased, and there was marked healing of atopic dermatitis.
  • Three-quarters of Italians with mild-moderate atopic dermatitis had complete remission during the summer. Seaside holidays were more effective than mountain holidays.

Find out more...

We will be adding a detailed evidence summary on this topic in the near future.  Please check back soon to find out more.

Page last edited: 17 May 2011