QShould certain types of patients use a particular type of sunscreen?

A
Rachel Printy, PA-C

Rachel Printy, PA-C

PA-C

Medically reviewed on 07.01.24 by Gabriela Maloney, DO

For patients with rosacea or those who tend to have more sensitive skin, I commonly recommend a physical sunscreen (one that contains metal oxides such as titanium dioxide and/or zinc oxide) over a chemical one as the latter may occasionally cause stinging and burning. Eucerin Sensitive Skin and Neutrogena Sensitive Skin sunscreens are a couple examples of physical sunscreens.

Physical sunscreens reflect and scatter UV light. Chemical sunscreens work by absorbing UV light and include ingredients such as oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. Physical sunscreens work right away, whereas chemical sunscreens should be applied 30 minutes prior to UV exposure because of their mechanism of sun protection.

For patients with melasma or other dyschromias, I recommend a tinted sunscreen which contains iron oxide. One example would be Elta’s MD’s UV Clear with tint. Iron oxide is thought to reduce hyperpigmentation and melasma relapses secondary to visible light by absorbing, scattering, and reflecting it. Examples of visible light are nature’s sunlight, ceiling lights, and our phones and computer screens. Most sunscreens without tint only provide limited protection against the visible light spectrum, even if they have the label of being broad spectrum. I recommend to my melasma patients that they wear sunscreen daily, even if they don’t go outside, because of their exposure to visible light indoors.

Many patients want to know what SPF they should choose. SPF is measured as the ratio of the amount of UV radiation required to burn the protected skin (with sunscreen) to that required to burn the same unprotected skin. This means when SPF 50 is applied, it will protect the skin until it is exposed to 50 times more UVB radiation than that required to burn the unprotected skin. The American Academy of Dermatology recommends SPF 30 at a minimum, as SPF 30 still allows about 3 percent of UVB rays to hit your skin. SPF 15 allows about 7%, SPF 50 around 2%, and SPF 100 around 1%. They also recommend a broad-spectrum sunscreen (one that protects against both UVA and UVB rays), and choosing a water resistant one. Most adults need about one ounce (think of a shot glass) to cover their whole body.

The key thing is that patients reapply their sunscreen every 2 hours or right after swimming or sweating – and preferably they should towel the moisture off their skin first.

But can the difference between SPF 50 and 100 really make an impact? I live in Colorado, so I found the following study set in Vail particularly interesting:

A total of 199 healthy adults participated in a split-face, randomized, double-blind study in which SPF 50+ was applied to one side of the face and SPF 100+ to the other. The participants then received an average of 6.1 +/- 1.3 hours of sun exposure while skiing/snowboarding. Erythema was assessed the next day via an investigator-blinded evaluation. It was found that 40.7% of the participants exhibited increased erythema scores on the SPF 50+ protected side as compared to 13.6% on the SPF 100+ protected side.

Likewise, another study performed on 55 healthy participants who spent 5 days on a beach using either SPF 50+ versus 100+ showed that the 100+ sunscreen was significantly more effective in protecting against ultraviolet radiation-induced erythema and sunburn.

References:

  1. Latha M, Naveen Kumar B. Sunscreening Agents, a Review. J Clin Aesthet Dermatol. 2013 Jan;6(1): 16-26.
  2. Dumbuya H, Wangari-Talbot J. Impact of Iron-Oxide Containing Formulations Against Visible Light-Induced Skin Pigmentation in Skin of Color Individuals. J Drugs Dermatol. 2020 July; 19(7) doi:10.36849/JDD.2020.5032
  3. Williams J, Rigel D. SPF 100+ sunscreen is more protective against sunburn than SPF 50+ in actual use: Results of a randomized, double-blind, split-face, natural sunlight exposure clinical trial. J Am Acad Dermatol. 2018 May;78(5):902-910.e2
  4. Kohli I, Hamzavi I. Greater efficacy of SPF 100+ sunscreen compared with SPF 50+ in sunburn prevention during 5 consecutive days of sunlight exposure: A randomized, double-blind clinical trial. J Am Acad Dermatol. 2020 Apr;82(4):869-877