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Sunscreen | Everything You Need to Know About Sunscreen, According to Skin Experts


Mahlagha Homayouni


August 5, 2021


Sunscreen; a friend for all seasons

Sunscreen is essential for skincare and health. Almost all dermatologists have recognized the importance of using sunscreen and consider wearing it as the first step and the most important way for long-term skin health.

The use of sunscreen prevents dangerous diseases such as skin cancer. About 85% of skin cancer patients are exposed to ultraviolet rays due to skin exposure. According to published statistics, melanoma skin cancer is increasing and the main causes of melanoma in people with a history of sunburn arise from exposure to sunlight. Sunscreens can also be mentioned as the strongest anti-aging creams for the skin because sunlight and ultraviolet rays are the main causes of wrinkles and freckles on the skin.

Skincare is very important for all skin types with any genetic type. Also, taking care of your skin will make your skin healthier and clearer, and will prevent the signs of aging in the person later. In this article, we intend to tell everything you need to know about sunscreen, according to skin experts.


skin assessment

Chapter 1

History of wearing sunscreen

Since the Middle Ages, man has realized the connection between the sun and skin damage. By describing the electromagnetic spectrum, the ultraviolet light spectrum is identified as responsible for skin damage caused by prolonged skin exposure to the sun. Sunscreens have long been used in various sizes to limit exposure to sunlight.


Awareness of the dangers associated with sunlight has increased in the last century, and as a result, science, technology, and formulation have advanced significantly. The use of sunscreen products is still on the rise as care providers seek to restrain the growing UV melanoma.

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Be tanned naturally instead

Recreational sunbathing and artificial tanning have significantly increased the risk of these diseases. The purpose of this article is to review the scientific principles of sunscreen use, their classification, formulation, control and quality regulation in different countries of the world.

Frequent exposure of the skin to the sun can lead to short-term and long-term changes in the structure of the skin. In the short term, this exposure causes erythema (reddening) of the skin, commonly referred to as sunburn. Following erythema, melanocytes are activated, which increase melanin production (melanization), which darkens the appearance of the skin.

The effects of frequent and prolonged exposure to the sun include a loss of skin elasticity that is irreversible and may lead to skin cancer. The extent of skin damage depends on the duration of sun exposure, changes in radiation intensity due to seasonal changes, geographical location, and host-related factors such as age, skin colour, behavioural factors, immune status, and more.

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Chapter 2

Sunscreen’s regulation

The use of sunscreens to protect against the harmful effects of the sun has increased in recent decades. This may be due to increased awareness of the possible harmful effects of repeated exposure to the sun. Repeated exposure to the sun increases the risk of three types of cancer: melanoma, basal cell carcinoma, and squamous cell carcinoma, which together with melanoma cause higher mortality. Non-melanoma skin cancers, on the other hand, were more common and associated with more skin damage.

Various clinical studies have shown that regular use of sunscreen can reduce skin cancer, especially melanoma and squamous cell carcinoma. There is also evidence of the protective role of sunscreens against skin damage caused by sunlight.

Formulation and science of sunscreens have evolved with the advancement of scientific knowledge and technologies. The increase in melanoma has led to regulatory concerns about the quality of sunscreen products and has led to increased demand from authorities to review the quality of sunscreen products.

The use of sunscreens has increased significantly in the last few decades. With increasing awareness of the protection provided by sunscreens against sunburn, skin-aging and melanoma, the demand for sunscreens increases significantly and there is a significant opportunity for the pharmaceutical industry to produce quality, safe, and efficient sunscreens.

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Chapter 3

Types of sunscreens

Different types of sunscreens are available to buyers in the competitive market of the world of fashion and cosmetics. The formulation of some creams is herbal, such as the French brand Yves Rocher. The formulation of the creams determines their types. Some sunscreens are coloured and some are colourless. Those who do not want their complexion to be too white usually use a sunscreen with their own skin colour, which is like a powder cream.

What does SPF mean in sunscreen?

You must have been familiar with the word SPF in the news and on the sunscreen box. In fact, SPF stands for sun protection factor. Research has shown that sunscreens with SPF 30 emit up to 97% of harmful rays and SPF 50 to 98% of harmful sun rays. For this reason, doctors consider the use of sunscreen with SPF 30 to be sufficient for the skin. Maria Sharapova, the world women’s tennis legend, is a fan of sunscreens with SPF 15 to 30.

If you have oily skin, non-greasy and matte sunscreens are a good option. Matte sunscreens are light and leave your skin glowing. In fact, the best sunscreen is a cream that is matte, free of fat and parabens, and has a good moisturizing (hydrated) ability.

Some sunscreens are waterproof and you can use them when exercising. Especially for women who do sports such as tennis, swimming and running on hot summer days, waterproof sunscreens are recommended. Note that waterproof sunscreens should also be reapplied after a while.

Common Mistakes About SPFs

Some women think that SPF 30 is twice as effective as SPF 15. While this is not the case and this assumption is not correct. You should be aware that SPF 15 actually protects your skin from one-fifteenth of the sun’s harmful rays, while SPF 30 prevents 97% of all UVB rays from damaging your skin. 50 SPF sunscreens, on the other hand, prevent 98% of UVB rays from hitting the skin.


SPF 30 is usually enough for a sunscreen suitable for all skin types. In addition to SPF, pay attention to the protection of the skin from UVA rays.

When buying sunscreen, pay attention to the fact that its SPF corresponds to your needs and you have carefully examined its formulation. Consider its expiration date and avoid buying sunscreen from vendors. Many sunscreens only protect your skin from UVA rays, and dangerous UVB rays still have the power to damage the skin. To know the difference between UVA and UVB, pay attention to the following:

  • The sun’s UVB rays damage the outer layers of the skin and cause sunburn.
  • UVA rays cause wrinkles and premature aging of the skin and damage the skin’s DNA.
  • UVA rays are a major cause of skin diseases and skin cancers.
  • Wrinkles are the effects of premature aging and damaged DNA of skin cells.

When buying sunscreen, look for the word broad spectrum on the box. This phrase shows that sunscreen is useful for oily skin and dry and combination skin and protects the skin against UVA-UVB rays.

Do not forget the sunscreen for kids and teenagers

In order for children and adolescents to have acquainted with the proper use of sunscreen in adulthood, they should be introduced to the use of sunscreens and skin moisturizers from the age of 4.

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Chapter 4

Important facts in choosing sunscreen

  • Some sunscreens contain alcohol, so do not expose them to direct sunlight for long periods of time.
  • The SPF should not be less than 15.
  • When using sunscreen, always consult a dermatologist.
  • Try to use sunscreen between 15 and 30 minutes before leaving the indoor area.
  • Sunscreens, like primers, foundations, tanners, and perfumes, take time to show their value and quality.
  • Too little use of sunscreen is not useful for covering a large part of the face and hands.
  • Do not forget that even under the roof you need sunscreen.
  • Pancake makeup is never a good alternative to sunscreen.

Some important facts that utter by experts and dermatologists

Who should use sunscreen?

If you ask what is the only useful care to delay skin aging, the answer is definitely the use of sunscreen, so everyone benefits from wearing it. Of course, those who are exposed to the sun for more hours due to their job need to use creams more.

Do we have to use sunscreen while we are at home?

We need to know that ultraviolet rays are also reflected in the house through indirect light and even fluorescent lamps, so if there is a lot of light in the house, it is better to use the cream at home.

What time of day should we use sunscreen?

Ultraviolet rays are at their highest from 10 am to 3 pm. Therefore, it is better not to leave the house during these hours as much as possible, and if necessary, use a cream that protects the skin from ultraviolet rays.

Do we really have to reapply sunscreen every 2 hours?

Yes. In case of prolonged exposure to the sun, it should be renewed every 2 to 3 hours.

What is the right sunscreen for all skin types?

  • Sunscreens come in a variety of forms such as creams, gels, foams and, etc
  • Creams are usually suitable for dry and normal skin
  • Gels and foams are usually suitable for oily skin

What are the characteristics of a good sunscreen?

  • It is broad-spectrum, which means it protects the skin against UVA and UVB rays
  • It has a suitable SPF
  • It should be suitable for your skin type
  • Better be water-resistant

What do broad-spectrum sunscreens mean?

As mentioned before, sunlight has two types of harmful UVA and UVB rays, and overexposure to these rays causes premature aging, wrinkles on the skin, and blemishes and freckles, and finally, it may increase the risk of skin cancer. Sunscreens that protect your skin from both UVA and UVB rays are called broad-spectrum. It is strongly recommended to use these sunscreens outdoors.

Chapter 5

What does mineral and chemical sunscreens mean?

Minerals usually contain zinc oxide and titanium dioxide. It is less popular because of the white color it leaves on the skin. These types of sunscreens are mostly used for damaged skin after rejuvenation and beauty procedures, and also for children and people with sensitive skin.

Chemical sunscreens, on the other hand, usually contain the following ingredients:

  • Oxybenzone
  • Avobenzone
  • Octisalate
  • Octocrylene
  • Homosalate
  • Octinoxate
  • Retinyl palmitate

It is recommended to use creams that do not contain oxybenzone and retinyl palmitate, for they can enter the bloodstream or provoke allergic skin reactions and retinyl palmitate may increase the rate of growth of tumours and skin lesions. Of course, some creams contain a combination of mineral (physical) and chemical ingredients.

Features of mineral sunscreens

  • It is effective as soon as it is applied. However, for more effective performance, it needs to be absorbed. This sunscreen may be removed by contact with skin or sweat.
  • Almost never irritates the skin.
  • It may leave a white mark, especially on darker skin.
  • Because mineral sunscreen is easily removed, it needs more care. Also, due to the formulation, you should use a lot of this type of cream to better protect your skin.

Features of chemical sunscreens

  • The effectiveness of this sunscreen begins about 15-30 minutes after use. But for more effective performance it needs to be absorbed.
  • Usually, chemical sunscreens have a thinner texture than physical ones.
  • These types of sunscreens are mostly chosen because of their water-resistant formulations. Because when wet or sweating, they do not leave a white mark. However, you should renew both types of sunscreens regularly.
  • This type of sunscreen may be allergenic for people with very sensitive skin.

Does sunscreen prevent the absorption of vitamin D?

Fortunately, there is no such concern about this, studies have shown that the amount of vitamin D in people who use sunscreen regularly and normal people (who do not wear sunscreen) is not much different. Most people receive vitamin D from food.

Is it necessary to use sunscreen in autumn and winter?

The use of sunscreens is not limited to summer, because the harms of sunlight also affect the cold seasons, and the phenomenon of sunburn will also occur in these seasons. Statistics released in the United States show that more than 20% of Americans suffer from skin cancer and skin damage during the cold seasons.

The sun’s rays are as harmful to the skin in summer as they are in winter, so it is obvious and necessary to use sunscreen in the cold months. The reasons for using sunscreen in autumn and winter are as follows:


  • Ultraviolet rays are not destroyed by cold air, and cold weather does not reduce their effect on the skin.
  • Cloudy weather does not block all UVB rays because the clouds cannot block ultraviolet rays.
  • UVA rays pass through the glass. Staying indoors or in the car does not protect you from the harmful effects of ultraviolet rays.
  • Cold weather decreases skin’s moisture, so the damage of sunlight will increase, so the use of sunscreen with natural oils along with moisturizers will lead to greater protection of the skin.


  • Snow reflects more than 80% of ultraviolet rays, and the damage from these rays to the skin will be doubled.
  • Due to the thin atmosphere at high altitudes, ultraviolet rays increase there. For every 300 meters above the surface, 4% will be added to these rays.
  • In winter and mostly in the middle of the season, the earth has the shortest distance from the sun, so the harmful effects of the sun’s rays also increase.
  • The Earth’s ozone layer, which is the sun’s own sunscreen, thins in winter and becomes as thin as possible, absorbing more ultraviolet light.

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Chapter 6

Classification of sunscreens and light protection mechanisms

In general, sunscreens are classified into two approaches; topical and systemic. Topical sunscreens are divided into organic and inorganic based on their protection mechanism. Inorganic sunscreens are sometimes referred to as sunscreen creams.

Systemic sunscreens

These are sunscreens that are absorbed by the body and accumulate in the skin and protect it from UV rays. Common examples of this group are ascorbic acid; Beta carotene; Alpha-tocopherol; Corticosteroids; Selenium and, etc. Systemic sunscreens are rarely used for everyday use.

Light protection mechanism

Sunscreens work by preventing and minimizing the damaging effects of the sun’s ultraviolet rays. Sunscreens have been shown to increase skin resistance to ultraviolet rays. They operate mainly through the following two mechanisms:

  • Scattering and reflection of UV energy from the skin surface. Mineral sunscreens work primarily through this mechanism. They provide a cover that prevents the sun’s rays from penetrating through the skin.
  • Absorption of ultraviolet energy by converting it to heat energy thus reduces its harmful effects and reduces the depth of its penetration into the skin. Organic sunscreens work through this mechanism.

Several organic compounds are commonly incorporated into sunscreen chemicals to provide protection against a wide range of UV spectra.

Types of sunscreens based on SPF and their effectiveness

SPF 15

Creams with this SPF can block one-fifteenth of the sun’s harmful rays.

SPF 30

These creams protect the skin from 97% of the sun’s rays.

SPF 50

Sunscreens with SPF 50 prevent 98% of sunlight from hitting the skin.

Ideal sunscreen properties

Favourable chemical properties include; ineffectiveness, non-irritability, stability and compatibility with other materials. Physical properties include low viscosity to enhance good dispersibility, aesthetic attractiveness, small particle size, water resistance, good solubility and odorlessness. Functional features include the ability to provide protection against a wide range of wavelengths and limited surface adsorption through the skin to minimize sensitivity. Products should also be easily accessible, inexpensive and pollution-free.

What are the characteristics of a good sunscreen?

  • It has a wide spectrum and protects the skin against both ultraviolet rays (UVA and UVB).
  • It should have an SPF of 30 or higher for better coverage. The best SPF for sunscreens is between 30 and 50, and higher SPFs are not suitable.
  • Sunscreen should be suitable for and compatible with the skin.

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Chapter 6

Last words

Sunscreens are important products that are used as protection against harmful UV rays. Increasing awareness of the dangers of constant sun exposure and its association with cancer has led to increased demand for sunscreen. Proper use of sunscreens is essential because their ability to protect against aging skin, tanning and melanoma has been proven.

Regulatory agencies around the world have also developed policies to increase oversight of the production of quality, science-consistent sunscreen products. Pharmacists understand the scientific principles of topical medications and can adjust sunscreens that meet all safety requirements, quality effectiveness, and consumer consent.

Sunscreen formulations continue to evolve with new techniques that enhance product design and effectiveness. Since the “sunscreen classification” has changed from general cosmetics to therapeutic drugs, the combination of quality and design concepts in the production of sunscreen products has been considered.

Some parents are reluctant to use sunscreens because of concerns about the effects of the chemicals. They rather use hats, masks, or some coverings, but experts strongly recommend using sunscreen for children to prevent sunburn and other skin conditions. Bear in mind that, do not use sunscreen for babies under 6 months.

Children’s sensitive skin is vulnerable to the sun’s harmful UV rays; Therefore, protecting their skin from the sun and using children’s sunscreen is essential as the first and most important step. Children’s skin is thinner than adults’ skin and the absorption of chemical ingredients of sunscreens is higher in children’s skin. On the other hand, children’s bodies can not tolerate these compounds as much as adults. Some sunscreens can cause allergies, even in adults with sensitive skin. Therefore, it is better to use sunscreens without harmful compounds for the health of children to reduce the risk of allergies.

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What a sunscreen does?

If you're going to be out in the sun, sunscreen is a great way to protect your skin. Ultraviolet radiation from the sun damages skin cells. This can led to sunburn, aging and even skin cancer. Sunscreens combine different ingredients to help stop UV rays from damaging your skin.

Is SPF 50 sunscreen good?

Properly applied SPF 50 sunscreen blocks 98 percent of UVB rays; SPF 100 blocks 99 percent. When used correctly, sunscreen with SPF values between 30 and 50 offers adequate sunburn protection, even for people most sensitive to sunburn.

Is SPF 50 good for skin?

A good sunscreen blocks harmful UVA and UVB rays that have the potential to wreak havoc on your skin by aggravating signs of ageing, pigmentation, and fine lines.

Can I use sunscreen without moisturizer?

Then, no matter how much non-sticky moisturizer and sunscreen you buy, combining both of them can make it thick on your skin. Thus, it is uncomfortable to use. My advice for oily skin people would be to use, lotion or moisturizer with SPF protection that can provide you both – softness and protection from harmful rays.

Which SPF is best for face?

Ideally, look for SPF 30 or higher. Know your skin type: If you have dry skin, choose a face sunscreen with hydrating ingredients, says Dr. Zeichner, like hyaluronic acid or ceramides. If you have oily skin, look for sunscreens that have a matte finish.

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