A Dermatologist's Guide to Sunscreen

Posted by Azadeh Shirazi MD on

Protecting our skin from the sun is an everyday essential, especially with the longer, stronger UV-rays that summer brings. While sunshine can uplift our spirits, provide vitamin D, and improve sleep, it's vital to choose the correct sun-care products for your skin type. As a dermatologist, I'm committed to educating my patients and readers about the significance of sun protection. Let's explore SPF in-depth, dispel myths and highlight benefits.

Sun rays are NOT created equal

UVA rays have the longest wavelength among the three types of UV rays. They can penetrate deep into the skin and are the primary cause of skin aging. UVA rays can contribute to the development of wrinkles, fine lines, and age spots.

UVB rays have a shorter wavelength and primarily affect the outer layer of the skin. They are responsible for sunburns and can play a key role in the development of skin cancer.

HEVL (High Energy Visible Light) is the blue/violet band of visible light with a high level of energy. Studies have shown it contribute to premature skin aging, hyperpigmentation, and discoloration.  

What Does SPF Stand For and What Do The Numbers Mean?

Sun Protection Factor tells you how well the product is going to protect your skin from UVB rays. For example, SPF30 means it will take 30 times longer to get a sunburn with that product than it will without. 

There are 3 tiers of SPF. 

-Low Protect  >SPF15

-Medium Protection SPF 15 - 29

-High Protection SPF 30 - 50+

If you apply small amounts of sunscreen, higher SPF numbers like SPF100 are beneficial as less product is required. Nevertheless it doesn’t block 100% of the sun’s rays. It’s important to note that SPF speaks only of UVB protection and not from UVA or HEVL.  

To protect against UVA use a broad-spectrum SPF 30 or higher. Suncare products with mineral blockers such as iron oxide also offer protection against HEVL, the sun that comes through windows and visible light from screens and phones. Hydratint BB SPF44 is my favorite broad spectrum sunscreen moisturizer as it offers broad spectrum protection against all forms of light that have the potential to damage the skin leading to discoloration and photo-aging. Plus it hydrates the skin giving you a filter like appearance.

What Is The Difference Between Chemical and Mineral Sunscreens?

The primary distinction lies in how mineral and chemical sunscreens function against UV rays. Mineral sunscreens act as physical blockers by forming a barrier on the skin's surface to prevent UV rays from penetrating. They contain dense ingredients like zinc oxide or titanium dioxide. In contrast, chemical sunscreens behave like sponges, absorbing UV rays into the skin and converting them into heat to prevent sun damage. They incorporate ingredients such as oxybenzone, avobenzone, octisalate, octocrylene, homosalate, or octinoxate, known for their lightweight feel and clear finish.

Is Sunscreen Toxic?

Sunscreen is generally considered safe when used as directed. However, some sunscreen products may contain certain ingredients that can potentially cause adverse reactions or have environmental concerns. It's important to be aware of these ingredients and make informed choices when selecting sunscreen. Sunscreen ingredients with potential for concern are:



These ingredients are also unsafe for the environment, harmful to the ocean’s reef structures.

Which Type Of Sunscreen Is Best For My Skin type?

I favor mineral-based sunscreens over chemical ones due to their safety for both our skin and the environment. Chemical sunscreens can cause irritation, particularly for those with sensitive skin, whereas mineral sunscreens create a protective barrier on the skin's surface, reducing the risk of irritation. Additionally, chemical sunscreens may exacerbate hyperpigmentation due to the heat they generate. Mineral sunscreens, containing ingredients like zinc oxide, are natural, less irritating, and include soothing properties that are antimicrobial and anti-inflammatory, making them ideal for sensitive and acne-prone skin types.

Chemical sunscreens offer lightweight and versatile formulations that can benefit oily, combination, or normal skin types. These formulations include options such as oil-free or mattifying products. This is particularly advantageous for individuals with combination skin, who may experience oilier areas in their T-zone and drier patches on other parts of their face.

Dr. Azi’s Recommended Products:

Hydratint BB SPF44: protects your skin from harmful UV rays while giving you a filter like appearance. Great for a soft summer coverage.

Supergoop Unseen Sunscreen: Broad spectrum SPF40, an oil free formulation that helps hydrate the skin. Clear application, does not leave a white residue with an elegant texture. 

UV Clear SPF Powder: perfect on the go mineral powder sunscreen brush for easy reapplication. Protects from UVA/UVB rays. Only contains 4-ingredients making it ideal for even the most sensitive skin types.

EltaMD UV Clear SPF 46: broad spectrum oil-free formula is particularly appealing for those with acne-prone skin as it includes lactic acid, an exfoliant that encourages cell turnover and Niacinamide to reduce breakouts.

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Dr. Azadeh Shirazi, MD is a Board-Certified Dermatologist.

Specializing in medical, surgical, and cosmetic dermatology, Dr. Shirazi received her undergraduate and medical degrees from the University Of Kentucky College of Medicine. After doing a Research Fellowship at Harvard Medical School at the Wellman Center for Photomedicine, she completed her residency training in Dermatology and Cutaneous Surgery at the prestigious Mayo Clinic in addition to completing her training in dermatology and cosmetic surgery at the University of California San Diego.

She has received multiple research scholarships from iconic institutions including Harvard University and the University Of Texas Southwestern Medical Center and has several peer-reviewed publications to her name.