The Difference Between Physical and Chemical Sunscreens

Physical sunscreens protect your skin from the sun by deflecting or blocking the sun’s rays, while chemical sunscreens work by absorbing the sun’s rays. Some chemical filters can scatter sun rays, but still mostly just absorb them.

All sunscreens have an active ingredient (also known as a UV filter) that protects you from the sun.

Physical UV Filters:

  • Titanium dioxide (TiO2)
  • Zinc oxide (ZnO)

Chemical UV Filters:

  • Octylcrylene
  • Avobenzone
  • Octinoxate
  • Oxybenzone
  • Homosalate
  • Helioplex
  • 4-MBC
  • Mexoryl SX and XL
  • Tinosorb S and M
  • Uvinul T 150
  • Uvinul A Plus

Stability

You want to choose a sunscreen which has active ingredients that are photostable, meaning they retain their stability upon exposure to sunlight and are unchanged. Physical UV filters are generally stable, however you do want to be careful when choosing a chemical sunscreen, as not all of them stay unaffected with sun exposure (avobenzone, for instance, is notoriously unstable).

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All EltaMD sunscreens at NewDermaMed are formulated with zinc oxide, which is the most photostable sunscreen ingredient.

Comedogenicity

Many people with oilier, break out prone skin tend to stray away from using an SPF because they worry it may worsen their skin. Chemical filters tend to be more irritating to the skin, and in some cases, may even cause allergic reactions. Those with problematic skin will want to choose a sunscreen formulated with zinc oxide, as it is generally safe and can be used even on the most delicate skin. Titanium dioxide can cause problems for some people. If you break out from mineral makeup, it’s the titanium dioxide that could be the culprit.

Protection

Chemical filters generally offer more coverage against UVA and UVB rays than physical sunscreens, but the range of protection will depend on the photostability of its active ingredient. Because your skin needs to time to absorb chemicals, you need to wait 20 minutes post-application for effective sun protection.

Titanium dioxide protects against UVB rays, but not the full spectrum of UVA rays. Zinc oxide is the most photostable sunscreen ingredient, and protects against the entire spectrum of UVA and UVB rays. All physical sunscreens begin protecting you immediately upon application.

Texture

Physical sunscreens are thick and opaque, and can sometimes leave a white cast or tint on the skin. It can rub off more easily and must be frequently reapplied. Chemical sunscreens are colorless, odorless, and usually runny. They can even double as a makeup primer, depending on the active formulation.

Safety

All physical sunscreens have been deemed safe and are completely approved by the FDA. While chemical sunscreen are generally safe, some chemical filters can actually generate free radicals, which can cause skin damage, irritation, and even aging. Many chemical UV filters have not been approved by the FDA, but are commonly found in sunscreens sold in Europe and Asia.

Photoaging and UV Exposure

As part of the Ontario Skin Cancer Prevention Act, youths under the age of 18 have been banned from using tanning beds as of this past Thursday, May 1st – perfectly timed, considering May is Skin Cancer Awareness Month. The goal of the legislation is to protect young people, who are especially vulnerable to damage from UV radiation leading to skin cancer. According to the World Health Organization, the use of tanning beds by individuals under the age of 35 increases your chance of skin cancer by a whopping 75%. In fact, the WHO classifies tanning beds among its highest risk category, which includes tobacco and asbestos.

Aside from serious health effects, long term exposure to UV rays has been proven to cause photoaging by damaging the skin’s collagen and elastin fibres, resulting in premature wrinkles and fine lines. Other side effects of prolonged UV exposure are as follows:

  • Both UVA and UVB cause damage to DNA, with UVB in the epidermis and UVA deeper in the dermis.
  • This damage causes mutations in the p53 tumor suppressor gene, a gene responsible for repairing damaged DNA (if possible), or discarding cells that are damaged beyond repair.
  • If p53 doesn’t function properly, these highly damaged cells continue to multiply.
  • Around 50% of skin tumors have this mutated p53 gene in them.
  • UVA penetrates deeper into the skin reaching the dermis where collagen, the structural scaffolding of the skin, is located. This causes the skin to sag in places leading to wrinkles.
  • Both UVA and UVB cause the number of Langerhans cells, an important part of the immune system, to decrease, lowering immunity.
  • UVA increases the number of inflammatory cells in the dermis.

Generally, the effects of UV exposure on the skin are permanent, however, thanks to scientific breakthroughs and advances in medical grade technology, they can be minimized and in some cases, completely reversed. Professional treatments like IPL Photo Rejuvenation and Laser Genesis are specifically designed to treat the most common age concerns that are so often a direct result of excessive tanning in our youth, such as deep wrinkles, fine lines, loss of skin elasticity, uneven tone and texture, redness/Rosacea, freckles and age spots, etc;

Taking simple precautions in your everyday routine, such as wearing sunscreen, can also have a hugely positive effect on the overall/longterm condition of your skin. Always choose an SPF formulated with zinc oxide, which is far more photostable than any other sun protecting ingredient.

NEW PRODUCT: EltaMD UV Clear SPF 46

We’re very excited about this new product! Leading sunscreen maker EltaMD has released a hydrating sunscreen specially formulated for acne prone skin. With an SPF of 46, this oil-free, noncomedogenic moisturizer leaves no residue, while calming and protecting sensitive skin types prone to acne, rosacea and discolouration from harmful UVA/UVB rays. This silky, lightweight formula can be worn alone or under makeup.

All EltaMD sunscreens are formulated with a natural mineral compound called zinc oxide. Unlike some chemical ingredients that may degrade, zinc maintains its protective ability in the sun, making it far more photostable than any sun protecting ingredient. Zinc blocks the widest spectrum of UVA and UVB rays while keeping the skin from burning and minimizing the premature appearance of aging and risk of skin cancer. Zinc is safe for even the most sensitive skin types!

Image via EltaMD.com

Remember: The risks associated with sun exposure are not exclusive to the summer season, and protection from UV radiation is important all year round. UV rays from the sun can reach you even on cloudy days, and also reflect off of surfaces like water, cement, sand, and snow.