Tips for using sunscreen

What should the sunscreen label say?

The broad spectrum wording and SPF number do different jobs, despite sharing a very small piece of packaging. SPF is not a timer: SPF 30 does not mean you can stay outside 30 times longer. The amount applied, strength of sunlight, swimming and sweating all affect protection. A higher number does not replace reapplication.6

How to apply sunscreen

1. 1Check the expiry date and read the directions before applying. Different sunscreen formats can have different instructions.
2. 2Apply at least 15 minutes before going outside. For an outing long enough to risk burning, UK guidance uses two applications: 30 minutes before leaving and again just before going out.
3. 3Cover all skin that clothing does not cover. Spread sunscreen generously and evenly, and rub it thoroughly into the skin.
4. 4Check the easily missed areas: ears, nose, back of the neck, shoulders, backs of hands, tops of feet, hairline and exposed scalp. Ask someone to help cover your back if you cannot reach it.
5. 5Apply a lip balm with SPF 30 or higher to your lips. Use a hat to cover a thinning or exposed scalp.
6. 6Reapply every two hours while outside, and sooner after swimming, sweating, towel drying or rubbing sunscreen off.

How much sunscreen is enough?

For an adult's whole body, about 7 teaspoons, or 35 ml, is a useful guide: one teaspoon for each arm, each leg, the front, the back, and the face and neck together. The UK whole body guide is 6 to 8 teaspoons. Cover exposed areas generously rather than trying to stretch a small amount across them.27

For the face specifically, the American Academy of Dermatology advises at least one teaspoon, roughly enough to cover the length of your index and middle fingers. That is more generous than the Canadian guide's teaspoon for face and neck together. Body size and the amount of uncovered skin change how much you need; a thin application reduces protection.12

A sunscreen lip balm covers a spot the body bottle tends to leave out of its job description. Keep ordinary sunscreen away from your eyes and mouth.57

Does water resistant sunscreen need reapplying?

Yes. No sunscreen is waterproof, and water resistance does not cancel the need to reapply after getting out of the water. Follow the label's 40 or 80 minute water resistance limit during swimming or sweating, and reapply after towel drying. Do not wait for the usual two hour interval after sunscreen has washed or rubbed off. Water also reflects UV rays, while its cooling effect can make burning less obvious.235

Which format should you use?

Lotions, creams, gels and sticks are all sunscreen formats, so the bottle does not have to look like beach equipment. Read the application directions for the format you choose. Never spray sunscreen directly onto your face. Keep spray sunscreens away from open flames and follow their warnings, because many contain flammable alcohol.35

If preventing dark spots is a priority, consider a tinted sunscreen containing iron oxide alongside broad spectrum SPF 30 or higher protection. Iron oxide helps protect against the sun's visible light, adding protection relevant to dark spots.1

Use sunscreen beyond beach days

UV exposure happens whenever you go outside, including cloudy days and winter walks. Snow reflects UV rays. Check the UV index on a weather app or website; a reading of 3 or higher is a reason to consider sun protection. A tan is not a safe substitute for protection, and people of every skin colour can develop sun damage.1236

No sunscreen blocks all UV radiation. Use shade, a wide brimmed hat and clothing that covers exposed skin. Limit time outside around midday, when sunlight is strongest. Choose sunglasses labelled UV400 or 100% UV protection. If you also need insect repellent, apply sunscreen first and repellent second.36

Sensitive skin, medicines and children

Test a new sunscreen on a small area of your inner forearm, especially if you have sensitive skin, and check for a reaction after 48 hours. Stop using the product if you develop itching, a rash or another reaction. Try a sunscreen with different ingredients, and speak to a health professional about a concerning reaction or help choosing a replacement. Check labels if you have a known ingredient sensitivity or allergy.67

Some medicines increase sensitivity to sunlight. If you take medicines, ask your health professional about specific sun protection precautions. Take extra care if you burn easily, have many moles, or have a personal or family history of skin cancer.23

Keep babies under six months out of direct sunlight and ask a doctor before applying sunscreen. Use shade, a sun hat and light clothing that covers their skin. For children over six months, follow the sunscreen label and cover exposed areas, including ears, feet and backs of hands. Children's skin needs particular care because it is more sensitive than adult skin.256

Keep sunscreen usable

Keep sunscreen out of direct sunlight and excessive heat, including a hot car. Outdoors, keep the container shaded or wrapped in a towel. Discard expired sunscreen. In the US, sunscreen without an expiry date should be discarded three years after purchase; discard it if you do not know its age. On UK packaging, an open jar symbol with a number and M shows how many months it lasts after opening. Stop using a recalled sunscreen.2356

When to get medical help

Seek medical help for sunburn if you feel unwell or your skin swells badly or blisters. Stay out of the sun until the redness has gone. Report a new mole, growth or lump, or a mole or patch that changes size, shape or colour, to a doctor promptly.2