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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 08, 2021   -  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?

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

Physical Sunscreens:

Chemical Sunscreens:

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.

Article Resources

Last reviewed at:
08 Sep 2021  -  4 min read




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