What are the differences between Physical and Chemical Sunscreens?

Current research has conclusively proven Chemical Sunscreens act by absorbing UV light for a limited period (related to the SPF factor). These chemicals are able to reach the bloodstream and are found in the liver 72 hours after application.

Furthermore, these chemicals are only able to absorb UVB rays (the rays responsible for sunburn) and not UVA rays (the dermally penetrating rays responsible for photoaging, collagen degradation and some forms of skin cancer).

Physical sunscreens, on the other hand act by adhering to the surface of the skin and physically reflecting all of the harmful rays (UVA and UVB). They are not absorbed into the bloodstream. Physical sunscreens are a total sun block, provided they are not removed from the surface of the skin. The general rule with Physical Sunblocks is “you move it you lose it”. Although physical Sunscreens are water resistant, it is generally recommended that they are reapplied every 80 minutes to account for incidental bodily activities such as rubbing or excessive perspiration.

Although Physical Sunscreens cannot be given an SPF (as Sun protection is a mathematical equation relating to the length of time that a Chemical Sunscreen is able to absorb UV light once inside the skin), a physical sunscreen is the equivalent of an SPF 60+.

Physical sunscreens do not penetrate the epidermis and are primarily composed of inert minerals (such as Titanium Dioxide), therefore are significantly less allergenic or irritating. It is also recommended that acne sufferers use physical sunscreens which are less comedogenic than many chemical absorbers.

It is mandatory that all sun protection products display a Sun Protection Factor, although many consumers are unaware of the fact that this label only indicates the relative amount of protection from UVB rays. There are also other ingredients that must be included in a product to provide UVA protection.

In order for a sun protection product to provide broad-spectrum UVA & UVB protection zinc oxide AND titanium dioxide, must be included.

High SPF numbers can be misleading, as an SPF of 30 is not twice as protective as an SPF of 15.

When used properly:

  • SPF 15 protects the skin from 93% of UVB Radiation
  • SPF 30 protects the skin from 97% of UVB Radiation
  • SPF 65 protects the skin from 98% of UVB Radiation
How do I distinguish between Physical and Chemical sunscreens?

Always check the ingredients on the labels

Physical Sunscreen Chemical Sunscreen
Titanium Dioxide PABA
Zinc Oxide Octyl Methoxycinnamate
Zirconium Oxide Oxybenzone
Avobenzene Butyl Methoxydiebenzoylmethane
  Benzophenone

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