Sunscreen can come in all types of substances, from sprays and creams to lotions and liquids. In essence, the type that you should use all depends on your personal preferences, though there are some instances where one type of sunscreen may work better with your skin than another. Sunscreen is essential if you want to avoid such issues as sun burn and skin cancer, as they help to protect you from the ultraviolet rays of the sun. The main issue with selecting the best sunscreen to protect skin is that there are simply so many from which to choose.

In general, you should consider such factors as the price, if you like the feel of it on your skin and whether it fits the intended occasion. People with sensitive skin typically prefer ointments or lotions while others may prefer liquids and sprays. Those with acne should use sunscreen without oil. It is also important to understand that the higher the SPF, the better protection you receive from ultraviolet rays. If you are going swimming, you will want a water-resistant sunscreen.

What is a sunscreen?

Sunscreens come as lotions, creams, ointments, gels, liquids, sprays, sticks, and films. What they all have in common is that they contain at least one substance that has the capacity to reduce the amount of potentially dangerous ultraviolet light that passes through onto the skin. Whether the sunscreen chemical or chemicals reduce the amount of ultraviolet energy getting to the skin surface by blocking it, scattering it, or absorbing it, the end result is less damage to the skin.

sunscreen products today. The good news is that there is plenty of choice. The bad news is that there is plenty of choice.

I frequently suggest that patients approach this wide selection the same way they pick out clothes. When you buy clothes, you want something that looks good on you, is appropriate for the occasion, fits well, and is priced right. Pretty much the same rules apply in selecting a sunscreen. Moreover, most of us have different clothes – something for casual wear, something for work, something for special occasions, warmer clothes for winter, lighter clothes for summer. If you are serious about using sunscreens, you will probably need a few different ones – just like you need different clothes.

Some of the qualities of sunscreens that you should take into consideration include:

skin cancer.). The SPF tells you essentially nothing about UVA protection. UVA is the longest wavelength of ultraviolet light. It plays a role in increasing the risk of squamous cell carcinoma and melanoma. Because longer waves penetrate more deeply into the skin, UVA radiation is a significant contributor to premature aging of the skin.

All other things being equal (and they usually are not), the higher the SPF the greater the protection from UVB. But doubling an SPF factor does not double the protection. For instance, a SPF 30 sunscreen only provides 3% more UVB protection than an SPF 15. As a practical matter, beyond an SPF of 30 other factors often become more important – how much UVA protection is there?, how well does it stay on?, is it water resistant?, is it sweat resistant?

Because the SPF is measured by applying a sunscreen at a prescribed thickness, the actual SPF when you apply it to yourself may be less. The average person applies a sunscreen at one half the thickness (or less) required to achieve the stated amount of UVB protection. The implication of that fact is that when most apply an SPF 30, they are getting a much lower SPF.

But that may not always be entirely true. Why? Because even though all sunscreens are tested at the same thickness of application, some formulations provide the same protection at lesser thicknesses. The problem is that you and I do not generally know which ones those are. So, the best advice is apply a sunscreen at at least twice the thickness that you would normally apply another cream or lotion.

The FDA would do us all favor if it reconsidered its testing procedures to encourage companies to construct different products that could be applied more thinly and still provide the stated SPF rather than its current process which requires one size to fit all. Moreover, it would be very helpful if products had properties that helped make it clear how thickly they should be applied. For instance, suppose a sunscreen were formulated so that it “glistened” or produced a color prior to drying when applied at the optimal thickness. Alternatively, perhaps a sunscreen could have an applicator that measured just the right amount of sunscreen to apply. Before that time a useful guide is to apply a teaspoon of sunscreen to cover the face, two tablespoons to cover the entire body. If you are interested in learning more about some of the inadequacies of current FDA guidelines, you might check out an article on that subject published in the New York Times in 2007 (

Water resistant and Very water resistant?

Obviously, if you are going to be swimming, a sunscreen that does not come off in the water is desirable. The FDA does have a measure, however inadequate, to help you determine how effectively a sunscreen stays on in the water. Prior to 2002 a sunscreen that stayed on for up to 80 minutes was called water proof. Now the term is very water resistant. The term water resistant means that the sunscreen has stayed on for forty minutes under FDA determined conditions.

Okay, so that helps. But FDA determined conditions are not necessarily the condition under which you will be using the sunscreen. What if you are getting in and out of the water? Will it still stay on just as well as continuous soaking for the same amount of time? What about in a hot tub? Does water temperature affect it? Or the pH of the water in a pool? Or what about salt water instead of fresh water?

In any case, the terms water resistant and very water resistant are nevertheless helpful guides. The bottom line: Reapply often and monitor how the sunscreen works for you under the conditions in which you use it. You might also consider getting some sun protective clothing to wear while swimming. At least if that comes off, you (and others) will notice. The chemicals themselves do not seem to convey an increased cancer risk, and clearly the benefit they convey reduces cancer risk.

But the real question is whether sunscreen use causes skin cancer. Here the answer is a little more complicated.

The problem is that sunscreens all have “holes.” None completely prevent entirely against all ultraviolet wavelengths under all conditions. So, when you wear a sunscreen, you are still getting ultraviolet damage.

The argument that sunscreen use may increase the risk of skin cancer goes basically like this: if you wear a sunscreen, you will stay out longer in the sun. You may not get a sunburn, but the “holes” in your sunscreen mean that you are getting more ultraviolet damage (at least for the wavelengths that gets through those “holes”) than if you had not worn sunscreen and spent less time in the sun.

The answer to that objection is to not use sunscreens as a reason to stay out longer; and when you do, make sure you use broad spectrum sunscreens (since the biggest “hole” is UVA protection).

Another argument is that sunlight (mostly UVB) acting on your skin produces Vitamin D which may have a protective effect against certain skin and internal cancers. If you use sunscreen, you will produce less Vitamin D, and therefore you will be more likely to get cancer.

The American Academy of Dermatology recommends (and so do I) that any adult using sunscreens on a regular basis take 1,000 international units of Vitamin D daily. This dose is basically harmless and is probably a good idea in any adult whether you use sunscreens or not (I take it). The American Academy of Pediatrics recommends 400 international units a day for each child beginning on day one. So, take Vitamin D internally (the D3 form is the most effective) and don’t worry about sunscreens producing cancer.

Is there a certain age at which it is not important to use sunscreen anymore?

Yes, but it is not just a matter of age but of what you are doing, your history of skin cancer, and your life expectancy.

Many of my older patients point out that the damage was done years ago and ask if there is any point in continuing to use sunscreens. While it is true that much of the damage was done years before, there are still good reasons to keep using them if one still has a few years left and enjoys the outdoors.

First of all, it is entirely possible that some of the damage from years ago can be undone by following a good sun protection program. Clinically, I have seen this happen in many of the patients I have followed over the years, especially when the more highly effective sunscreens became generally available.

Second, classically we have thought of cancer development as proceeding in two stages–initiation and promotion. Initiation is the planting of the seeds. That is the damage that was done years ago. Promotion is the watering and fertilizing of the seeds to encourage them to sprout. Ultraviolet radiation is both an initiator and a promoter. So, even though the seeds may still be there, it makes sense not to encourage them to grow.

Do sunscreens become less effective over time?

In general, yes.

Ideally, a sunscreen product should have an expiration date on the package. If not, I recommend not using a product that is more than a year old.

A nice, but more technical review, on sunscreens can be found at

A less technical but good review of sunscreens can be found at

The Mayo Clinic has another well-written piece on sunscreens as well.

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