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SunscreensPatients with elevated 1,25(OH)2D need to block the production of vitamin D in the skin to avoid symptoms caused by natural light exposure. This is best done by staying indoors during daylight hours and covering up with dark clothing when daylight outings are unavoidable. See Light Sensitivity.

Sunscreens (sun blocks)

Most sunscreens are insufficient to protect against the effect of significant sun exposure. The use of sunscreen may cause patients to become too complacent about avoiding sunlight exposure.

"Effect of sunscreen on vitamin D synthesis; sunscreens are used to protect the skin from ultraviolet A (UVA) and UVB waveband exposure that is associated with deoxyribonucleic acid (DNA) damage—the same UVB exposure that is needed for vitamin D synthesis. Experimental studies suggest that sunscreens can decrease cutaneous vitamin D synthesis (Misra et al., 2008). However, emerging evidence suggests that although sunscreens are effective, many may not actually be blocking UVB because they are improperly or inadequately applied. Thus, sunscreen use may not actually diminish vitamin D synthesis in real world use, although further study is needed to verify its actual impact (Diehl and Chiu, 2010; Springbett et al., 2010)."
Dietary Reference Intakes for Calcium and Vitamin D (2011)Food and Nutrition Board (FNB)

The use of a certain type of sunscreen can block some of the production of vitamin D3, 25-D and 1, 25-D that occurs when light falls on the skin and might be helpful to some patients.

 

Zinc oxide
 
Most conventional sunscreens don’t prevent the photosynthesis of vitamin D in the skin. Zinc oxide, used in some sunscreens, appears to block the production of vitamin D3, 25-D and 1,25-D that occurs when natural light falls on the skin but it will not allow sun-sensitive patients to freely move outdoors.
 
The degree and length of protection will vary widely, depending on percentage of zinc oxide, degree of sensitivity, length of exposure, time of day, etc.
 
Its use should be limited to areas of the body that are difficult to cover with clothing.
 
Ketoconazole
 
2% Ketoconazole cream is a prescription topical antifungal medication. It’s sold under the brand names Nizoral and Daktarin. Studies have shown that topical Ketoconazole stops synthesis of 1,25-D in the keratinocytes of the skin.
 
The off-label use of Ketoconazole for this purpose is not recommended because it may be absorbed systemically and affect the vitamin D Receptor, thus potentially limiting recovery. It may also cause a rise in 25-D.
 
See also: