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Sunblock protects your skin by absorbing and/or reflecting UVA and UVB radiation.
The American Association of Dermatology (AAD) recommends that a "broad spectrum" sunblock with an SPF of at least 15 that is applied daily to all sun exposed areas, then reapplied every two hours. However, in some recent clinical trials sunblocks with SPF 30 provided significantly better protection than sunblocks with SPF15.
So while the best sunblock varies from individual to individual, we recommend a "broad spectrum" sunblock with UVA and UVB protection, a SPF rating of at least 30, in a form that is gentle enough for daily use.
Why is "broad spectrum" so important?
- UVB rays cause suntanning and sunburn, damage to DNA and skin cancer.
- UVA rays penetrate more deeply into the skin and is cumulative over time, causing photo-aging. Skin becomes leathery, dry, wrinkled with a loss of elasticity and decrease in collagen fibers. Precancerous and cancerous cells can form. UVA enhances the harmful effects of UVB.
Active ingredients of sunblock vary from manufacturer to manufacturer and can be divided into chemical versus physical agents.
- Chemical sunblocks work by absorbing the energy of UV radiation before it affects your skin.
- Physical sunblocks reflect or scatter UV radiation before it reaches your skin. Some sunblocks combine both chemical and physical sunblocks.
The two types of physical sunblocks that are available are zinc oxide and titanium dioxide. Both provide broad spectrum UVA and UVB protection and are gentle enough for everyday use. Because these are physical blocking agents and not chemicals, they are especially useful for individuals with sensitive skin, as they rarely cause skin irritation.
Most chemical sunblocks are composed of several active ingredients. This is because no single chemical ingredient blocks the entire UV spectrum (unlike physical sunblocks). Instead, most chemicals only block a narrow region of the UV spectrum. Therefore, by combining several chemicals,with each one blocking a different region of UV light, one can produce a sunblock that provides broad spectrum protection. The majority of chemical agents used in sunblock work in the UVB region. Only a few chemicals block the UVA region. Since UVA can also cause long-term skin injury, dermatologists routinely recommend sunblocks that contain either a physical blocking agent (e.g. titanium dioxide or zinc oxide) or Avobenzone (also known as Parsol 1789).
Application: All sunscreens should be applied 15-20 minutes before sun exposure to allow a protective film to develop, then reapplied after water contact and sweating. Some sunblocks can lose effectiveness after two hours, so reapply frequently.
Allergic reactions: The most common occur with sunscreens that contain PABA-based chemicals. If you develop a rash to a sunblock, check the label to see if PABA is an ingredient. If so, consider avoiding sunblocks that contains this in the future. Alternatively, try a titanium dioxide or zinc oxide containing sunblock as they rarely cause skin irritation and provide very good broad spectrum UV protection.
| Aminobenzoic acid |
UV-B |
| Avobenzone |
UV-A |
|
Cinoxate
|
UV-B
|
|
Dioxybenzone
|
UV-B, UV-A
|
|
Homosalate
|
UV-B
|
| Menthyl anthranilate |
UV-A |
| Octocrylene |
UV-B |
| Octyl methoxycinnamate |
UV-B
|
| Octisalate |
UV-B
|
| Oxybenzone |
UV-B, UV-A
|
| Padimate O |
UV-B
|
Phenylbenzimidazole sulfonic acid
|
UV-B
|
| Sulisobenzone |
UV-B, UV-A
|
| Titanium dioxide |
UV-A/B, broad spectrum
|
| Trolamine salicylate |
UV-B
|
| Zinc oxide |
UV-A/B, broad spectrum
|
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