Skin and Beauty

How to Select a Sunscreen?

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


Ultraviolet radiation like UVA and UVB has been well documented to have multiple effects on human skin. It not only causes 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.

Sun Protection Factor:

Sun protection factor (SPF) 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 sunburned. For example, SPF of 30 would allow you to stay in the sun 30 times longer than you could without protection. SPF refers to the degree of protection from ultraviolet B and does not provide protection against ultraviolet A.

Types of Sunscreen:

  • Sunscreen agents are classified as either chemical sunscreen, which absorb light or physical sunscreen, which reflect, scatter and absorb light.
  • Physical sunscreens like Zinc oxide and Titanium dioxide are always better than chemical sunscreens.
  • Comparing between Zinc oxide and Titanium dioxide physical sunscreen, Zinc oxide is superior in terms of UVA protection and is less pasty.
  • Avobenzone is the only 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 availability of these agents in sunscreen which give you a broader range of sun protection.

Sun Protection Measures:

Sun protection of photo exposed areas and certain measures to protect us from direct sunlight are as follows:

  1. Avoid midday sun, especially 10 AM to 4 PM. Seek shade whenever possible.
  2. Wear tightly woven cotton clothing with long sleeve 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 reflected.
  6. Then apply plenty of sunscreen to sun exposed areas in a concentration of 2mg/cm square.

How to Apply a Sunscreen:

To apply a sunscreen, follow the teaspoon rule:

  1. 3mL (slightly more than half a teaspoon) for each arm and for the face and neck.
  2. 6mL (slightly more than a teaspoon) for each leg, chest and the back.

The sunscreens protect the skin from damage by ultraviolet rays, provided they are applied liberally 30 minutes to 1 hour before an exposure. It should be reapplied after swimming or sweating or during prolonged ultraviolet exposure. A SPF of at least 30 should be applied to the most fair skinned individual and reapplied after 4 to 6 hours as there is no such completely waterproof sunscreen. So, reapplication is important.

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

For further doubts regarding sun protection, consult a dermatologist online -->

Last reviewed at: 07.Sep.2018



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