Sunscreen: How It Works, Why It Matters, and How to Choose the Right One

Sunscreen is one of the most effective ways to protect the skin from damage caused by ultraviolet (UV) radiation. Regular use of sunscreen helps reduce the risk of sunburn, premature skin ageing, and skin cancer. In Australia, where UV exposure is high year‑round, sunscreen plays an important role in everyday health.

Understanding how sunscreen works and how to choose the right product can help ensure it is used correctly and effectively.

What Is Sunscreen?

Sunscreen is a topical product designed to protect the skin from UV radiation. It works by either absorbing, reflecting, or scattering UV rays before they can damage skin cells.

There are two main types of sunscreen ingredients:

• UV absorbers, which absorb UV radiation and convert it into heat
• UV blockers, such as zinc oxide and titanium dioxide, which reflect and scatter UV radiation

Many modern sunscreens use a combination of both methods to provide broad protection.

What Does SPF Mean?

SPF stands for Sun Protection Factor. It indicates how well a sunscreen protects against UVB radiation, which is responsible for sunburn.

For example, SPF 30 means that, when applied correctly, the skin should take approximately 30 times longer to burn than unprotected skin. However, real‑world protection depends on correct application, reapplication, sweating, swimming, and UV intensity. This is why sunscreens need to be applied liberally and reapplied regularly. 

In Australia, SPF 30+ or higher is recommended for everyday sun protection.

Why Sunscreen Is Important

UV radiation can damage skin even on cooler or cloudy days. Sunburn is caused by UV exposure, not heat. Over time, repeated UV damage increases the risk of skin cancer and accelerates visible skin ageing such as wrinkles, pigmentation, and loss of skin elasticity.

Sunscreen is especially important for:

• Outdoor workers and tradies
• People spending extended time outdoors
• Children and older adults
• Anyone with fair or sun‑sensitive skin

How to Use Sunscreen Correctly

Sunscreen should be applied 20 minutes before sun exposure to allow it to form an effective protective barrier. It should be applied generously and evenly to all exposed skin.

For an adult, this equates to approximately 35 mL (seven teaspoons) for a full‑body application. Sunscreen should be reapplied at least every two hours, and more often after swimming, sweating, or towel drying.

Is Sunscreen Enough on Its Own?

Sunscreen should not be the only form of sun protection. For best protection, it should be used alongside other measures such as:

• Sun‑protective clothing
• Broad‑brimmed hats
• Seeking shade
• Sunglasses that meet Australian Standards

This combination approach offers the greatest reduction in UV exposure. 

Choosing the Right Sunscreen

Sunscreens come in different formulations, including lotions, sprays, gels, and cosmetic‑friendly finishes. Some are designed for daily wear, while others are formulated for sport, swimming, or long‑lasting outdoor use.

The best sunscreen is one that suits your skin type, lifestyle, and that you are comfortable using regularly. Pharmacists can help recommend an option that fits your needs and explain correct use.

See also:

• SPF explained: what the numbers really mean
• Sunscreen for children and sensitive skin
• Sunscreen for sport, swimming, and outdoor work
• How to apply sunscreen properly