How to Select a Sunscreen?
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How to Select a Sunscreen?

Written by
Dr. Suvash Sahu
and medically reviewed by iCliniq medical review team.

Published on Jun 18, 2016 and last reviewed on Sep 20, 2022   -  4 min read


The most common questions in dermatological practice are which sunscreen to use and while going out in the sun what are the sun protection measures to be followed. The answers are here in this article.

How to Select a Sunscreen?


Ultraviolet radiation like UVA and UVB have been well documented to have multiple effects on human skin. Ultraviolet radiation causes not only skin cancer but also cutaneous aging like seborrheic keratosis, photomelanosis (pigmentation on sun-exposed parts), wrinkles, polymorphous light eruption, melasma, freckles, lentigines, and urticaria or hives.

What Is a Sun Protection Factor?

Sun protection factor is also called SPF and is measured in the laboratory with a light source, and it is a theoretical amount of time you can stay in the sun without getting sunburns. For example, an SPF of 30 would allow you to stay in the sun 30 times longer than you could without protection. SPF is the degree of protection from ultraviolet B and does not provide protection against ultraviolet A.

What Are the Types of Sunscreen?

  • Sunscreen agents are classified as either chemical sunscreen, which absorbs light, and physical sunscreen, which reflects, scatters and absorbs light.

  • Physical sunscreens like zinc oxide (ZnO) and titanium dioxide are always better than chemical sunscreens.

  • On comparing zinc oxide and titanium dioxide physical sunscreens, zinc oxide is superior in terms of UVA protection and is less pasty.

  • Avobenzone is the only available chemical sunscreen agent that offers protection against the long-wave UVA, which is mainly responsible for cutaneous cancer, polymorphic light eruptions, and cutaneous lupus erythematosus.

  • So, before buying sunscreen, you must check the availability of these agents in sunscreen, which give you a broader range of sun protection.

What Are the Advantages and Disadvantages of Physical and Chemical Sunscreens?

Physical Sunscreens:

  • They contain substances like zinc oxide or can be available in combination with titanium dioxide.

  • It provides a protective seal over the skin's surface, reflecting and protecting the skin from UV light.

  • They tend to leave the skin with a white tinge.

  • It is made with minerals.

  • It is generally thicker and is hard to blend, so it is not preferred for everyday use.

  • After applying this sunscreen, there is no need to wait for 15 to 30 minutes because it starts to work instantly.

  • Physical sunscreens are preferred for people with sensitive skin (rosacea).

Chemical Sunscreens:

  • They contain organic and carbon-based compounds, which absorb UV light and prevent them from penetrating the skin.

  • They are absorbed fully into the skin but may cause irritation in people with sensitive skin.

  • It is made with UV filters.

  • It is generally lighter and non-sticky, so it can be used on the skin daily.

  • It takes at least 30 minutes to work, so apply the chemical sunscreens before 30 minutes of stepping out.

  • Chemical sunscreens are preferred for people with oily skin.

Why Are Water Resistance Sunscreens Preferred?

When you are going to the pool or beach in the summer, wearing water-resistant sunscreen is important because it helps the sunscreen to stay even when you are wet. But water-resistant sunscreens are a pretty smart option for daily use as well because the rule of thumb is that people should reapply sunscreen every two hours. And many of them do not realize that they are sweating more with their sunscreen throughout the day, especially when it is humid, so in such cases, water-resistant sunscreens give people extra protection even when they are not in actual water. Read the labels carefully whether it contains water resistance or not before buying. Also, sunscreen labels that say to be water-resistant must indicate how long the product can be worn while swimming or sweating in order to reapply it.

Why Does Broad-Spectrum Matter While Picking a Sunscreen?

Broad-spectrum is the sunscreen that protects against both UVA and UVB. According to the FDA, UVA causes wrinkles, and UVB rays cause sunburn and skin cancer. Most people tend to think about sunburns when it comes to sun protection. But the truth is, they do not know the different types of sun damage it causes. Ultraviolet A rays enter the deeper surface of the skin and may cause signs of aging. These ultraviolet A rays are present throughout the year; even when it is cloudy or sunny, they can enter the windows with the same intensity.

What Are the Sun Protection Measures?

Photo exposed areas need certain protective measures from direct sunlight. They are as follows:

  1. Avoid the midday sun, especially from 10 AM to 4 PM. Seek shade whenever possible.

  2. Wear tightly woven cotton clothing with long sleeves and long pants whenever going out in the sun. Also, wear broad-brimmed hats.

  3. Protect your eyes with UV-filtered sunglasses.

  4. Beware of high altitude places as there are fewer atmospheres to absorb UV rays.

  5. Be cautious at river beds, beaches, and snow places, as 80% of UV rays are reflected.

  6. Then apply plenty of sunscreen to sun-exposed areas in a concentration of 2 mg/cm square.

How to Apply a Sunscreen?

To apply sunscreen, follow the teaspoon rule:

  1. 3 ml, that is, slightly more than half a teaspoon, is applied for each arm and for the face and neck.

  2. 6 ml, that is, slightly more than a teaspoon, is applied for each leg, chest, and back.

The sunscreens protect the skin from damage by ultraviolet rays, provided they are applied literally 30 minutes to 1 hour before exposure. It should be reapplied after excessive sweating or swimming or during prolonged ultraviolet exposure. An SPF of at least 30 should be used by fair-skinned individuals and reapplied every 4 to 6 hours as there are no such sunscreens that are completely waterproof. So, reapplication is important.

Daily use of sunscreen is more protective than intermittent use. Sunscreen should be applied even on cloudy days.


Always look into the label while selecting a sunscreen, and check for words like ‘broad spectrum,’ which means the sunscreen can protect the skin from both UVA rays and UVB rays. Also, sunscreen with an SPF of 30 or higher should be preferred. The word ‘water-resistant’ on the label indicates that sunscreen can stay on wet or sweaty skin before it needs to be reapplied. Not all sunscreens offer water resistance, and water resistance lasts for 40 to 80 minutes. So, it is mandatory to look at the label for these words before buying sunscreens.

Frequently Asked Questions


What Are the Ingredients of the Sun Protection Factor?

Sunscreen is composed of active and inactive ingredients. Active ingredients help in protecting the skin from harmful UV rays of the sun. Inactive ingredients are all other remaining ingredients that are not active such as water or oil. The active ingredients that are acceptable in sunscreen are -
- Aminobenzoic acid.
- Avobenzone.
- Cinoxate.
- Dioxybenzone.
- Homosalate.
- Meradimate.
- Octocrylene.
- Octinoxate.
- Octisalate.
- Oxybenzone.
- Padimate O.
- Ensulizole.
- Sulisobenzone.
- Titanium dioxide.
- Trolamine salicylate.
- Zinc oxide.


What SPF Is Mostly Recommended?

The sun protection factor that is usually recommended is SPF 30 or higher than that. The SPF 30 blocks almost 97 % of the harmful ultraviolet rays of the sun. Despite, the higher SPF number, sunscreen cannot block 100 % of the sun rays.


What Is the Two-Finger Method for Sunscreen?

The two-finger method means squeezing the sunscreen along the length of two fingers and applying it over a part of the body, like the face or neck. This is the most trending method to apply a sufficient amount of sunscreen so that the whole body part is covered. This method can be used for every part of the body; just squirt enough sunscreen so that it covers the length from the crease of the palm to the tip of the index and middle fingers.


Does Higher SPF Cause Any Damage to the Skin?

The effect of higher SPF sunscreen is the same as other sunscreens. A higher SPF of 50 or more blocks almost 98 % of harmful ultraviolet radiations but not 100 %. So, it is often misleading that they provide more protection or can harm the skin, but people usually spend more time in the sun, thinking they will get more protection than lower SPF sunscreen.


Is Mixing Sunscreen With Moisturizer a Good Idea?

Some people mix sunscreen with moisturizer to get the quantity of sunscreen to cover the whole body or to make the sunscreen thin. But this is not a good idea as mixing moisturizer with sunscreen can dilute the sunscreen, making it ineffective, and it would be like turning SPF 30 or 50 into SPF 15. Moreover, it could affect the ultraviolet filters of the sunscreen, making them less effective.


What Are the Different Types of Sunscreens?

Sunscreen is generally of two types: chemical and physical.
- Chemical Sunscreens: These types of sunscreens are composed of multiple ingredients which get absorbed on the skin when applied. These sunscreens react with the skin and absorb ultraviolet rays, harming the skin instead of protecting it.
- Physical Sunscreens: Also called natural or mineral sunscreens are the most recommended sunscreens by FDA as they contain zinc oxide and titanium dioxide, which, when applied on the skin, acts as a shield and deflect the harmful sun rays.


Which Sunscreens Are the Safest?

The safest sunscreen is said to be mineral or physical sunscreen with zinc oxide or titanium dioxide. These are the only safe and effective sunscreen ingredients approved by the FDA (Food and Drug Administration). In comparison, chemical sunscreens act like sponges and absorb most ultraviolet rays that harm the skin instead of protecting it. Physical sunscreens act like a protective shield on the skin.


How to Protect Skin From Tanning?

Some of the following things can be done to avoid tanning.
- The first thing that can be done to avoid tanning is to avoid going out in the sun when it is at its peak between 12 PM to 4 PM.
- Cover yourself while going out to avoid direct exposure to the sun.
- Apply sunscreen for at least 15 minutes before going out.
- Stay hydrated and drink at least 10 to 15 glasses of water daily.
- Wash face at least twice a day.
- Eat healthy fiber-rich food like vegetables and fruits that boost immunity and protect from sun damage.


How Effective Are Natural Sunscreens?

Natural, physical, or mineral sunscreens are most effective compared to chemical sunscreens. Natural sunscreens provide broad-spectrum protection from harmful UVA and UVB rays and photodamage. In addition, these sunscreens are environmentally friendly as they do not dissolve in water while swimming.


Is Sunscreen Really Required?

The simple answer is yes. As with age, the skin gets damaged by skin exposure, and people who are more exposed to sun rays on a daily routine should use sunscreen to avoid further damage to the skin. Wearing sunscreen is one of the easiest and safest methods to protect the skin from harmful rays of the sun.


Can Aloe Vera Be Used as Sunscreen?

Aloe vera alone is not effective in protecting the skin from harmful ultraviolet rays. However, it can be used as a medicine in case of sunburn. Research suggests that solutions with aloe vera and SPF 14 to 16 are effective and can be used as sunscreen.


What Are the Alternatives to Sunscreen?

Some natural remedies can be used instead of sunscreen, but these are not effective as sunscreen; these include -
- Shea butter.
- Aloe vera.
- Coconut oil.
- Sesame oil.
- Sunscreen patches.


What Is the Frequency of Sunscreen Application?

Ideally, sunscreen should be applied every two hours when exposed to sun rays for a long time. The sunscreen should also be reapplied, especially after swimming or sweating too much. On the other hand, people who usually work indoors and away from windows might not need another sunscreen application.

Article Resources

Last reviewed at:
20 Sep 2022  -  4 min read




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