The Definitive Guide to Physical and Chemical Sunscreens

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There are two main types of sunscreen out there; physical and chemical. With each one having their own set of advantages and disadvantages, it is important to understand the differences between the two, so that you can make an informed decision when it comes to choosing the best sunscreen for your skin.

Why Is Sunscreen So Important?

Sunscreen is considered to be an over-the-counter drug, but unlike many other cosmetic products, it is regulated by the FDA.

It is basically a formula that acts as a barrier between your skin and the sun’s UV rays.

One frequently asked question is: 

If the body needs the sun every day to produce vitamin D, so surely the sun can’t be all that bad?

This is true, but the body only needs about 15 minutes of sunlight a day to produce enough vitamin D. 

After that, the UV rays begin to really cause some damage…

Here are just a few of the reasons you should be wearing a sunscreen:

  • Protects against premature aging
  • Significantly lowers the risk of skin cancer
  • Prevents sunburns and other skin blemishes
  • Prevents tanning, which is a symptom of sun damage

infographic - UV damage

Physical and Chemical Sunscreens

Now that you know why you need a sunscreen, it is time to understand the differences between physical and chemical sunscreens.

As you can tell from the name, a chemical sunscreen contains chemicals that absorb the sun’s UV rays.

Wondering what happens once the rays have been absorbed?

A chemical reaction that changes the electromagnetic radiation effect of the UV rays, meaning that they are then released from the body as infrared rays.

On the other hand, a physical sunscreen contains natural agents that have the ability to reflect the sun’s rays away from the skin.

physical vs chemical sunscreen

Chemical Sunscreens: Pros and Cons

Chemical sunscreens are the most easily available type, meaning that you are likely to find them wherever sunscreen is sold.

They are also thinner than physical sunscreens, meaning that they are easier to spread evenly across the skin, and you also do not need to use quite as much with each application. They also do not really have a color or an odor, making them quite appealing.

Due to the way in which chemical sunscreens are formulated, it is also much easier for skin care companies to add in other nourishing ingredients, whether this may be antioxidants or peptides.

While this may all sound great, there is a downside to chemical sunscreens…

Due to the fact that they contain so many ingredients, with many of these being harsh chemicals, they can often cause irritation and stinging, especially for those with sensitive skin. In fact, the higher the SPF, the higher the chances of skin irritations are.

Although they do contain chemicals, chemical sunscreens do not work immediately. You need to give them about 20 minutes after application before they are ready to kick into action. The chemicals also break down the longer they are exposed to the sunlight, so they need to be reapplied quite frequently.

As mentioned above, chemical sunscreens convert UV rays into infrared rays. These are invisible to the human eye, but can still be felt in the form of heat, meaning that your skin will heat up as the infrared rays are created and emitted from your body.

Why does this matter?

Because the extra heat can lead to a few problems…

Firstly, overheated skin will have an effect on any brown spots, or other areas of discoloration, that you may already have on your skin, by making them significantly worse.

The increased heat can also lead to redness, especially for those who already suffer from conditions such as rosacea.

For those who have an oily skin type, you need to be careful when using chemical sunscreens, as they do have the potential to clog up pores and exacerbate oiliness.

Physical Sunscreens: Pros and Cons

Just like with chemical sunscreens, there are a few things that you need to know about physical sunscreens…

For those who do not like planning in advance, physical sunscreens are extremely beneficial as they are effective immediately, meaning that you do not need to wait 20 minutes before they start working.

They also do not contain as many strong chemicals, meaning that they are less likely to irritate the skin, making them far better for sensitive skin types.

For those who have rosacea or other skin conditions that are exacerbated by heat, physical sunscreens are better, as they deflect the sun’s rays away from the skin, rather than absorbing them, therefore preventing them from coming into contact with the skin in the first place.

Unlike chemical sunscreens, physical sunscreens do not clog up the pores, and last for longer when exposed to direct UV light, meaning that you will not have to reapply them quite as frequently. However, if you have been exercising, or getting wet, both types of sunscreen will need to be reapplied.

Due to the white pigment that titanium dioxide has, physical sunscreens can often leave a white cast on the skin, which is more noticeable on darker skin tones. This also means that many formulas of physical sunscreen are incompatible with makeup, whether you wear it over or under your makeup.

Since physical sunscreens use physical molecules to deflect away the sun’s rays, they do need to be applied quite generously, as well as accurately, making sure that you cover every part of exposed skin.

Why is this so much more important with physical sunscreens?

Because if you only apply it sparingly, the sun’s UV rays will be able to access the spaces in between the molecules in the sunscreen, and therefore still enter your skin.

These molecules that make up the sunscreen are created by milling solid zinc oxide and titanium dioxide. However, in recent years, there have been concerns about whether or not these particles are absorbed into the skin.

This is something that you do not want, as the product is designed to sit on the surface of the skin.

What happens when the particles are absorbed?

Research in this area is still ongoing, but you do need to be aware of the potential health impact here. 

Ingredients in Physical Vs Chemical Sunscreens

There are only two physical UV filters that have been approved for use in physical sunscreens by the FDA:

  • Titanium dioxide – a natural mineral that has a distinct, white pigment and remains stable when exposed to UV rays
  • Zinc oxide – another natural mineral, and the only FDA approved ingredient that can protect against both UVA and UVB rays

Chemical sunscreens, on the other hand, can contain quite a wide range of ingredients.

Here are a few of the most common ones:

  • Para-aminobenzic acid – one of the first chemical UV filters used in sunscreen, but not as widely used any more as it can irritate sensitive skin
  • Avobenzone – the best chemical for UVA protection
  • Oxybenzone – acts like estrogen, and can cause allergies as well as endometriosis
  • Homosalate – disrupts hormone function within the body

Some of these ingredients are best avoided, so you do need to be diligent when choosing a chemical sunscreen.

So, Which One is Better?

When it comes to blocking UV rays, both physical and chemical sunscreens have similar levels of effectiveness. All sunscreens need to undergo a number of different FDA approved tests before they can be sold, to ensure that they do actually work.

Your choice between the two depends on all of the pros and cons that come with each type.

In fact, you may not even need to make the choice at all, as many sunscreens now actually contain both chemical and physical elements. This means that they will contain fewer chemicals than a purely chemical sunscreen, but will have a thinner consistency, and less of a white tint to it, than purely physical sunscreens.

Understanding SPF

Now that you have decided whether you want to go for a physical or chemical sunscreen, it is time to choose an SPF.

Do you know what SPF actually measures?

It is a rating of how well the sunscreen is able to block the sun’s UVB rays, as these are the rays that burn the skin.

However, while a higher SPF rating is better, keep in mind that no sunscreen can block 100% of the sun’s rays, which is why other forms of sun protection are also important.

So, what SPF do you actually need?

Dermatologists recommend an SPF of around 30. Although higher ratings are better, the difference between an SPF 50 and an SPF 100 is miniscule, and this is more of a marketing ploy.

No matter what SPF you choose, you need to make sure that you are reapplying your sunscreen every two hours, using about an ounce to cover your entire body. Keep in mind that you may need to use more if you have opted for a physical sunscreen.

What is Broad Spectrum?

A broad spectrum sunscreen is one that protects against both UVA and UVB rays. Most ingredients will only protect against one or the other, which is why multiple ingredients need to be combined in sunscreen formulas to create a broad spectrum product.

Needless to say, the sunscreen that you use should definitely be broad spectrum. While it is the UVB rays that cause burning and skin cancer, it is the UVA rays that lead to wrinkles and other signs of premature aging, meaning that you will need protection from both.

effects of UVA and UVB on skin

Does Sunscreen Irritate Your Skin?

A common complaint about sunscreen, and one of the reasons as to why many do not wear it, is that it irritates the skin. However, there are so many different sunscreen formulas out there, and chances are that it is a chemical one that will have caused skin irritation.

Rather than refraining from using sunscreen at all, try out a few different types, as you will no doubt be able to find one that works in harmony with your skin.

Other Forms of Sun Protection

As mentioned above, no sunscreen will protect you from 100% of the sun’s UV rays, so you need to make sure that you are taking other steps to protect your skin as well.

Wondering what you need to do?

Here are a few tips:

  • Avoid direct sunlight during the sun’s strongest hours – these are usually between 11am and 4pm, although this does depend on where you live
  • Wear protective clothing your clothes should be loose and breathable, but should cover exposed skin as much as possible. Keep in mind that if you can see through the fabric, then the sun’s UV rays will be able to get through the fabric too. Dark and tightly woven fabrics are best
  • Use stylish accessories sun protection does not need to be boring! Large, stylish sunglasses will protect the delicate skin around your eyes from the sun, but make sure that the glasses you choose have UV protection. Hats are also great, but go for canvas rather than straw, as canvas is more tightly woven, and therefore better able to block out UV rays
  • Beware of side effects to any medication you may be taking – many drugs, as well as herbal remedies, make your skin much more vulnerable to UV rays, and increase your risk of sunburn 

UV density at different times of the day

Sun protection is something that you do need to take extremely seriously. The majority of people out there do not use enough sunscreen, but this leaves them susceptible to everything from premature wrinkles to skin cancer. While remembering to apply sunscreen every single day can seem like a bother at first, you will soon get into the routine of doing this, and it will become second nature.

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