Burning questions about sunscreens answered by dermatologists - Theo10 | Made-In-Singapore Skincare Products

While you may already know you should be using sunscreen daily, you might have wondered how sunscreen actually works—or how long it really lasts, or what the SPF number on the bottle means. 

Why Wear Sunscreen?

Besides protecting you from sunburn (if your skin type does burn), why should you wear sunscreen? 

Sunscreen helps prevent skin cancers. The three most common types of skin cancer are basal cell skin cancer, squamous cell skin cancer and melanoma. UV radiation is the top risk factor causing these skin cancers. Consistent, adequate protection from the sun’s UV rays helps lower your risk, which is why it’s critical to apply sunscreen every day.

Sunscreen prevents premature aging. The culprits of the aging process are divided into two categories: intrinsic aging (influenced by genetics) and extrinsic aging (induced by chronic exposure to the sun’s radiation, pollution, chemicals and other environmental factors). UV radiation causes the premature breakdown of collagen and elastin in skin, resulting in fine lines and wrinkles. It also damages pigment-producing cells called melanocytes, resulting in the overproduction of melanin causing hyperpigmentation. The sun’s ultraviolet radiation is responsible for an estimated 90 percent of visible signs of aging. Regular use of sunscreen allows you to enjoy smooth, youthful-looking skin for years longer.

Sunscreen reduces the risk of hyperpigmentation. A common skin condition caused by sun exposure, hyperpigmentation is when your skin is darkened in patches due to changes in the production of melanin, which gives skin its color. People with darker skin are naturally more susceptible to hyperpigmentation.

Sunscreen prevents inflammation of the skin. UV radiation damages the DNA of immune-protecting cells, leading to inflammation and free radical damage to skin and within the body. Immune suppression decreases our body’s ability for these cells to protect us from skin cancers and other illnesses. The immune system plays a vital role in maintaining the health of all the tissues of the body, so healthy skin is vital to overall health.

Sunscreen prevents sun sensitivity. Sunscreens are particularly helpful in preventing solar irritation in people with sun-sensitive conditions, such as lupus and rosacea, where exposure to UV rays can lead to redness and burning in the skin and overall severity of these conditions.

How does sunscreen work?

This actually depends on which type of sunscreen you’re using. mineral or physical sunscreen ingredients, which include zinc oxide and titanium dioxide, work by physically blocking and scattering the sun’s rays. Chemical sunscreen ingredients (like avobenzone, homosalate, octinoxate and others) work by absorbing UV rays before they can damage your skin. Both types of sunscreen will effectively protect your skin.

What is SPF and what do those numbers mean?

SPF stands for “sun protection factor” and it measures the level of protection against UVB rays, or the rays responsible for sunburn. According to Dr. Diane Berson, a New York dermatologist and member of the MDSolarSciences Scientific Advisory Council, an SPF of 15 protects against 93 percent of UVB rays, SPF 30 protects against 97 percent and SPF 50 protects against 98 percent. Sunscreen brands use independent testing companies to test the SPF levels in their products in compliance with the Food and Drug Administration’s (FDA) testing guidelines.

“The SPF number theoretically correlates to how long a person can stay in the sun without burning,” says Dr. Berson. “For example, when wearing an SPF 30, you can remain outside for 30 times longer than if you were unprotected. However, that doesn’t take into consideration your skin type, any toweling, swimming, sweating or the level of the UV index that particular day.” Another important consideration: Sunscreen breaks down on skin over time, which means you must reapply every two hours to continue getting the level of protection noted on the product’s label.

“When choosing a sunscreen, make sure that you’re choosing a product that has been tested for broad-spectrum protection (protects from both UVA and UVB),” Dr. Berson says. “That way, you’ll be protected not only from the immediate effects of sun damage (sunburn) but also from long-term damage that shows up as wrinkles, sunspots and worse—skin cancer.”

Find out more about the difference between UVA and UVB as well as physical sunscreens vs chemical sunscreens at: https://theo10.com/theo10-sunscreens/

Does sunscreen prevent tanning?

You can get a tan while using sunscreen, because no formula can protect against 100 percent of UV rays. This doesn’t mean tanning—even while wearing SPF—is at all healthy for your skin. Any darkening of the skin is a result of damage being caused by UV rays, and can increase your skin cancer risk.

How long does sunscreen last, and how often should I reapply?

Many factors might contribute to how long sunscreen protection lasts such as the UV index and whether you’re sweating or swimming As a rule of thumb, experts recommend reapplying your sunscreen every two hours.

“With the new FDA regulations, it’s much easier for people to understand the need to reapply at least every two hours, and every 40 or 80 minutes while swimming or sweating. These directions are now easily seen on the packaging,” says Dr. Berson.

When can babies wear sunscreen?

Dr. Lamb says it’s not recommended for newborns to wear sunscreen until they’re at least six months old. Instead, keep babies in the shade and covered with hats and clothing. Once they’re old enough, consider a sunscreen specifically designed for babies and to reapply sunscreen more often just to be safe.

THEO10 Sunscreen


Introductory video: https://www.youtube.com/watch?v=8O01LJSa_nU

Theo10® Sunscreen is a moisturizing SPF50 sweat and water-resistant sunscreen which strictly contains no harmful substance to humans and the ocean. It effectively deflects harmful UV rays before they reach the protective outer epidermis layer of the skin. Theo10® Sunscreen is a broad-spectrum protection formulated sunscreen for protection against both UVA and UVB.

We ensure that the ingredients we use do no harm to humans and oceans particularly reefs. Our sunscreen contains non-nano and uncoated particles and food grade organic ingredients.

While most sunscreen whitens the applied area, Theo10® Sunscreen does not leave any traces of whitening features, instead, it moistens and grants an occlusive layer to retain the barrier against moisture loss and sunscreen protection.

Suitable for:

  • Young Children
  • Sensitive Skin
  • Dry or oily skin
  • Up to 90min water-resistant


  • Cold Pressed Jojoba Oil
  • USP food grade Vegetable glycerine
  • Non-nano Non-coated Therapeutic Grade Zinc Oxide
  • Non-nano Non-coated Therapeutic Grade Titanium Dioxide
  • Cold Pressed Snow Pear oil

Method of Application:

Ideally should be applied at least 30 minutes prior to sun exposure to allow it to be fully functional.

To purchase: https://theo10.com/product/theo10-sunscreen-60ml/

Adapted from: https://www.dermstore.com/blog/why-wear-sunscreen/