From the Guidelines
Sunscreen works by creating a protective barrier on your skin that blocks or absorbs harmful ultraviolet (UV) radiation from the sun, and it is crucial to use broad-spectrum sunscreen with SPF 30 or higher to prevent skin cancer and premature aging. There are two main types of sunscreens: physical (mineral) sunscreens containing zinc oxide or titanium dioxide that sit on the skin's surface and reflect UV rays away, and chemical sunscreens with ingredients like avobenzone or oxybenzone that absorb UV radiation and convert it to heat. For effective protection, apply a broad-spectrum sunscreen with SPF 30 or higher approximately 15 minutes before sun exposure, using about one ounce (enough to fill a shot glass) to cover exposed areas of an average adult body. Reapply every two hours or immediately after swimming or sweating.
According to the U.S. Food and Drug Administration, broad-spectrum sunscreens with a sun protection factor of 15 or greater protect against both UV-A and UV-B radiation and reduce the risk for skin cancer and early skin aging 1. The American Family Physician also recommends using sunscreen with a high sun protection factor (>15) on exposed skin for residents of areas of high insolation who work outdoors or enjoy regular outdoor recreation 1.
Some key points to consider when using sunscreen include:
- Using sunscreen in combination with other protective measures, such as wearing protective clothing and seeking shade, especially during peak sun hours 1
- Avoiding the use of sunscreen as a means of extending the duration of solar exposure 1
- Applying sunscreen daily to exposed skin, especially for individuals who work outdoors or enjoy regular outdoor recreation 1
- Being aware of the potential risks of skin cancer, especially for fair-skinned individuals, and taking steps to prevent sunburn and premature aging 1
Overall, using sunscreen is an important part of a comprehensive sun protection plan, and it is essential to choose a broad-spectrum sunscreen with a high sun protection factor and apply it correctly to maximize its effectiveness.
From the FDA Drug Label
Uses ■ helps prevent sunburn ■ If used as directed with other sun protection measures ( see Directions), decreases the risk of skin cancer and early skin aging caused by the sun Uses • helps prevent sunburn • if used as directed with other sun protection measures (see Directions), decreases the risk of skin cancer and early skin aging caused by the sun
The FDA drug label does not answer the question.
From the Research
How Sunscreen Works
- Sunscreen works by protecting the skin from ultraviolet (UV) radiation, which can cause sunburn, skin damage, and skin cancer 2, 3, 4, 5, 6.
- There are two main types of sunscreens: inorganic and organic 2, 5.
- Inorganic sunscreens, such as titanium dioxide and zinc oxide, form a physical barrier on the skin's surface to reflect and scatter UV rays, providing broad-spectrum protection 2, 4, 5.
- Organic sunscreens, such as octocrylene and avobenzone, absorb into the skin and absorb UV radiation, converting it into heat, which is then released from the skin 2, 4, 5.
Sunscreen Ingredients
- Octocrylene and avobenzone are stable and provide UVA and UVB protection with minimal adverse effects 2.
- Oxybenzone is harmful to the neuroendocrine system and should be avoided 2.
- Titanium dioxide works for broad-spectrum UV protection and offers minimal adverse effects 2, 4.
Sun Protection Factor (SPF)
- SPF is a measure of a sunscreen's ability to protect against UVB radiation, which is primarily responsible for sunburn and skin cancers 3, 5.
- A higher SPF does not necessarily mean better protection, as it only measures protection against UVB radiation, not UVA radiation 3, 5.
- Broad-spectrum sunscreens that protect against both UVA and UVB radiation are recommended 3, 4, 5.
Proper Use of Sunscreen
- Sunscreen should be applied regularly and in sufficient amounts to provide adequate protection 3, 5.
- Reapplication is necessary, especially after swimming or sweating 2, 3.
- Sunscreen use should be combined with other forms of sun protection, such as wearing protective clothing and seeking shade, especially during peak sun hours 2, 3, 5.