Some sunscreens say they are water-resistant or waterproof and can protect for about 40 minutes in the sun if a person is doing a water activity.
Applying a sunscreen
- Apply the sunscreen at least 30 minutes before going in the sun.
- Apply sunscreen to all the skin that will be exposed to the sun, including the nose, ears, neck, scalp, and lips. Sunscreen needs to be applied evenly over the skin and in the amount recommended on the label. Most sunscreens are not completely effective because they are not applied correctly. It usually takes about 1 fl oz (30 mL) to cover an adult's body.
- Apply sunscreen every 2 to 3 hours while in the sun and after swimming or sweating a lot. The SPF value decreases if a person sweats heavily or is in water, because water on the skin reduces the amount of protection the sunscreen provides. Wearing a T-shirt while swimming does not protect your skin unless sunscreen has also been applied to your skin under the T-shirt.
Other sunscreen tips
The following tips about sunscreen will help you use it more effectively:
- Older adults should always use a sunscreen with an SPF of at least 15 to protect their very sensitive skin.
- If you have sensitive skin that burns easily, use a sunscreen with an SPF of at least 15.
- If you have dry skin, use a cream or lotion sunscreen.
- If you have oily skin or you work in dusty or sandy conditions, use a gel, which dries on the skin without leaving a film.
- If your skin is sensitive to skin products or you have had a skin reaction (allergic reaction) to a sunscreen, use a sunscreen that is free of chemicals, para-aminobenzoic acid (PABA), preservatives, perfumes, and alcohol.
- If you are going to have high exposure to the sun, consider using a physical sunscreen (sunblock), such as zinc oxide, which will stop all sunlight from reaching the skin.
- If you need to use sunscreen and insect repellent with DEET, do not use a product that combines the two. You can apply sunscreen first and then apply the insect repellent with DEET, but the sunscreen needs to be reapplied every 2 hours.
Do not use tanning booths to get a tan. Artificial tanning devices can cause skin damage and increase the risk of skin cancer.
For information on sun exposure and vitamin D, see Getting Enough Vitamin D.