Can Sunlight Help My Eczema?

Our relationship with sunlight can seem complex. On one hand, ultraviolet (UV) radiation is the biggest risk factor for skin aging and skin cancer. On the other hand, sunlight is necessary for vitamin D production and may benefit chronic skin conditions like eczema.

How can the sun help my eczema?

It is not 100% clear how the sun helps with eczema, but vitamin D produced in the body from the sun’s UV rays plays an important role in regulating the immune system.

The role of vitamin D and skin

When your skin is exposed to UVB rays from sunlight, it creates vitamin D from cholesterol in your skin cells. Vitamin D increases another substance called cathelicidin (pronounced cathel-iss-id-in), which is also an important part of the body’s immune function. People with eczema have been found to have low concentrations of cathelicidin in their skin, which is thought to lead to worse eczema symptoms. 

The role of sunlight

Beyond vitamin D, the lack of sunlight appears to have a negative effect on the body’s natural immune system and contributes to inflammatory skin conditions like eczema. A recent study showed that infants who received more exposure to UV light by 6 months of age had lower incidences of eczema.

Scientists believe UV rays can also have other local effects on the skin. Another compound released into the bloodstream when the skin is exposed to UV rays is nitric oxide. Nitric oxide in the bloodstream triggers an immune response that helps reduce swelling and pain, keeping overactive immune systems in check. This is also why you may see some skin doctors offer UV light therapy as a treatment option for eczema.

So, how much sun should I get?

There are no concrete time recommendations or guidelines around UV exposure, as it is difficult to balance this with cancer risk, and the intensity of UV rays changes throughout the year. What is right for you will also depends on your skin type – darker skinned people have a harder time producing enough vitamin D from the sun, so they will likely need more exposure time.

Consider these factors to improve your vitamin D levels and get some safe sun exposure:

During the summer, noon (12 PM) is the best time to get a few minutes of direct sunlight because UVB rays are the most intense. Because of this, you do not need to be out for too long (the body might also be the most efficient at producing vitamin D at this time).

Although there are no precise time-limits for being out in the sun to get the right amount of vitamin D, most studies cite time limits between 13 – 30 minutes, from 3 times a week to 7 times a week (daily). One study found fair skinned people only needed to spend 3-8 minutes in the sun to make 400 IU of vitamin D; the length of time may be longer if you have a darker skin tone.

Bare skin exposure is required to produce vitamin D. Avoid sunscreen application and covered clothing for a few minutes on areas like the legs, arms, hands, and face.

Note: You don’t need too much sun! A 10-minute walk in the midday sun can create as much as 15x the amount of vitamin D that you need per day.

What if my eczema gets more irritated with the sun?

Less than 5% of people find their eczema gets aggravated in the sun. However, sweat caused by being in the sun can irritate eczema. So, if your skin feels more irritated when it’s exposed to even a small amount of direct sunlight, avoid it! Make sure to stay protected with clothing, sunscreen, and shade.

Bottom line

If you have eczema or other chronic skin conditions, like psoriasis, you may find a small amount of natural sunshine helpful! However, not everyone’s skin reacts in the same way, so take note of how your skin responds and consider the risk factors of getting too much UV radiation to find the right balance for you. If you have questions, talk to your doctor to make sure you know what the best UV light options are.

References:

1. Yu, C., Fitzpatrick, A., Cong, D., Yao, C., Yoo, J., Turnbull, A., Schwarze, J., Norval, M., Howie, S., Weller, R. B., & Astier, A. L. (2017). Nitric oxide induces human CLA+CD25+Foxp3+ regulatory T cells with skin-homing potential. The Journal of allergy and clinical immunology, 140(5), 1441–1444.e6. https://doi.org/10.1016/j.jaci.2017.05.023
2. Thyssen, J. P., Zirwas, M. J., & Elias, P. M. (2015). Potential role of reduced environmental UV exposure as a driver of the current epidemic of atopic dermatitis. The Journal of allergy and clinical immunology, 136(5), 1163–1169. https://doi.org/10.1016/j.jaci.2015.06.042
3. Rueter, K., Jones, A. P., Siafarikas, A., Lim, E. M., Bear, N., Noakes, P. S., Prescott, S. L., & Palmer, D. J. (2019). Direct infant UV light exposure is associated with eczema and immune development. The Journal of allergy and clinical immunology, 143(3), 1012–1020.e2. https://doi.org/10.1016/j.jaci.2018.08.037
4. Thyssen, J. P., Zirwas, M. J., & Elias, P. M. (2015). Potential role of reduced environmental UV exposure as a driver of the current epidemic of atopic
5. dermatitis. The Journal of allergy and clinical immunology, 136(5), 1163–1169. https://doi.org/10.1016/j.jaci.2015.06.042
6. Health Canada. (2019). Vitamin D and Calcium: Updated Dietary Reference Intakes. Retrieved from https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/vitamins-minerals/vitamin-calcium-updated-dietary-reference-intakes-nutrition.html
7. Gill, P., & Kalia, S. (2015). Assessment of the feasibility of using sunlight exposure to obtain the recommended level of vitamin D in Canada. CMAJ open, 3(3), E258–E263. doi:10.9778/cmajo.20140037
8. Terushkin, Vitaly et al. (2010) Estimated equivalency of vitamin D production from natural sun exposure versus oral vitamin D supplementation across seasons at two US latitude. Journal of the American Academy of Dermatology, 62(6), 929.e1 – 929.e9
9. Choosing Wisely Canada. Retrieved From https://choosingwiselycanada.org/vitamin-d-tests/