November 21, 2022

Whenever the sun is shining: sunscreen! – tips by Dr. Liv

Salut, it’s me again, Dr. Liv Kraemer. I am a dermatologist living and working in Zurich, Switzerland. Summer is finally coming – and so is your summer vacation. So, naturally, you will start to wonder: Do I really need sun protection? How does sun protection work? What is the best sunscreen for the face? Which ingredients are safe? What sunscreen is best for me? What is the best suncream for acne? If you know me already, you will probably have heard me say many times: “Always wear sun protection, because the sun always shines!” But why is that? Let me explain!

Sun and sun protection: whenever the sun is shining

If I ask my patients: “Do you wear sunscreen?”they more often than not reply: “Of course, always – on the beach!” Whenever I hear that answer, I roll my eyes. And I say: “Honestly, I don’t care about your 60 days of holidays and weekend getaways – I do care, however, about the 305 grey-in-grey average Swiss days.” Why? It’s easy: Daytime means sun, night means no sun. During daytime, the sun is always shining. If the sun isn’t shining, it is night. It’s simple physics. And yes, physics matter to your skin!

How does sunscreen work?

Let me explain it differently. Maybe you remember your chemistry lessons. You stood there and waited and waited for a long time for a reaction to take place. Then your chemistry teacher came and switched on the Bunsen burner – and suddenly the reaction took place immediately! That’s exactly how it happens with the sun.

The sun is a bundle of different wave lengths. As you probably know: Without the sun, nothing would grow. Therefore, you can compare the Bunsen burner from your chemistry lessons in school with the sun. Without it burning, nothing would ever happen.

Be sure, I don’t want to explain the whole range of sun energy levels. So let’s short cut it short and just look into two different wave lengths: the UVA and UVB light.

What does UV stand for?

UV is the abbreviation for “ultraviolet”, referring to ultraviolet radiation. The best known forms of ultraviolet light are ultraviolet A and ultraviolet light B. Both have different wave lengths. Therefore, they also have different energy spectra. Confusing!?

Ok, let me explain it: You know the visible light, of course – the light or colors you can see. Then, of course, there’s also light you cannot see. Some of these forms of light, you can feel in a kind of heat or warmth. For example the UVB light. Unfortunately, the more problematic one, the UVA radiation, you can neither see nor smell nor feel. And this is what it makes it so dangerous.

What is UVA and UVB light?

Ultraviolet light B is a high intense light with a wave length from 280 to 315 nm. UVA, on the contrary, is much richer in energy with a wave lentgh between 315 and 400 nm.

Of the solar ultaviolet energy that reaches the equator, only 5 % is UVB and 95 percent is UVA light. Anyhow, “broad-spectrum ultraviolet radiation [UVA and UVB] is the strongest and most damaging to living things,” according to the NTP’s 13th Report on Carcinogens.


Which one is worse – UVA or UVB light?

It depends. Both do a lot of harm. For skin cancer, sun burn caused by UVB is more problematic.For causing wrinkles, pigmentation and rednesses, UVA plays a bigger role. Let me explain: UVB is much lower in energy. It gets reflected by the window glass and does not penetrate the skin deeply. UVA, instead, goes deep into the skin. It causes pigmentation and redness. Why? Because it penetrates the skin so deeply that it enters the deeper skin layers. UVA also destroys the collagen in your face. Therefore, UV-A causes collagen and elastin loss. You get wrinkles.

UVB, on the other side, is – from the pure medical side – more problematic. Why? Because it can cause skin cancer. With genetic predispositions (your family history or, in other words, if your mom or dad or grandma suffered from skin cancer), your risk is generally higher. And if your exposed to the sun and its UVB radiation over a longer period of time, the chance is high that you will be developing skin cancer. 

Skin cancer and sun exposure

I know you are reading it everywhere…sun and skin cancer. But you are young and beautiful, and it won’t affect you! It is something for the elderly, you think. Wrong! My youngest patient who died from skin cancer was 14 years old.

But now I can hear you say: “Ok, poor her, but I’m different!” I hope so. But you do accumulate your sun damage. Compare it with your bank account. You want to collect more and more money to have, after maybe 5 years, enough to buy something nice. With the sun it is the same way – only reversed. You are collecting your damage with every sun exposure; and later, in 5 or 10 years, you get the problems.

Therefore consider wearing sun cream every day! In the USA, more than 2 million people are treated for two different white skin cancer types every year. One is basal skin cancer, the other is squamous skin cancer. They are rarely life threatening, but have to be treated as soon as possible to avoid big operations.

Black skin cancer, also called melanoma, is less common, but much more serious and dangerous. I always tell my patients: “Just like you go to the dentist for a check up once a year, go to your dermatologist for a skin check once a year!” Especially if someone in your family has had skin cancer, if you have a lot of moles or had a lot of sun burns in your childhood. That’s also why it is so important to protect your skin as early as possible – because prevention is much much better than reparing.

So… what about getting a sun tan?

As I mentioned in my Youtube video, a sun tan is just the natural defense of your body against the UVB light.

So …let’s compare it to Star Trek!

Imagine your Enterprise (your cells) gets bombarded by an enemy klingonen ship (the UV-B light), your space ship pulls out the protective shields. For your skin this means: If your face is exposed to the sun, your skin produces melanin which is giving your face your sun tan. So that’s how, in reality, your suntan is nothing else than a protection shield against the harmful UV-B radiation.

If we think further: What happens if you stay in the sun for longer, or, actually, for too long? Right, you get a sun burn. If we compare this to our Star Trek ship again, now it gets bombarded so heavily by the enemy ship that all the protection shields are falling down. Now you get your sun burn. 

The “healthy sun tan”

Yes, that’s what so many people are looking for, right. They want to get a tan, but in a healthy way. One that will not cause them cancer or wrinkles. Well… unfortunately, there’s one thing you need to remember: There is no such thing as a healthy tan. Any tan is already a sign that your skin is moving out its own protection shields (the melanin, the tan you can see) to defend itself against the harmful sun light.

If you are unlucky and you unfortunately have genetical predispositions (meaning: skin cancer in your family), you might get skin cancer. If we take our Star Trek comparison even one step further, the enemy ship is bombarding (UV B light) your own ship (skin cells) so heavily without yours having any protection shields left. In your own space ship, you now have an invader. You lost the game. You might develop a skin cancer. 

Do I also age form sun tanning beds?

Of course you do! UV radiation is UV radiation. It does not matter if it comes out of the plug socket or from the atmosphere. It once again is simple physics. There is even research that shows that HEV light, the blue light from your cell phones, can cause skin damage and therefore wrinkles. So next time you are using your iPhone or Android touchscreen phone, you better use your earplugs instead of holding it up to your cheeks. Of course, you are not getting sagging skin, wrinkles and pigmentation through sun exposure during your sun bath last week or one time on a sun tanning bed. It takes years and years of damage and damage. But it does add up! 

Ok… so I need to use a sunblock, right?

Let us be honest. Everything that sounds too good is too good. There is nothing like a sunblock! So – what blocks UV light? Cloth does. But not your light summer clothes will do – it will have to be rather thick garmets. Also remember this when using a sun hat. I had a couple of patients who were sitting in the sun with a hat, so proud to show me that they were taking my advice. But what they weren’t realizing was that this hat was actually “showing through”. To really block UV light, you need sun protective garmets with a certain knitting technique.

So, sunblock is a misleading term and will be hopefully gone from the market soon. A real sunblock is something like a heavy cloth with a certain knitting technique that does not let UV light penetrate.

Nonetheless, there are roducts that call themselves “sunblock” – so maybe you wonder what they are. Some people say that sun protection with ingredients like zinc oxide or titanium oxide are sunblockers.These two ingredients are indeed working as physical sunscreens and reflecting the UV light. These two sunscreen ingredients both provide a white film on your skin.

This white film is working as a protection shield. Certain rays get reflected. But the white film has to be stable on the skin.

Unfortunately, we sweat, we keep putting our hands in the face …and we wipe that shield away. Also, the so-called peak absorbant rate from titanium dioxide works good for UVB, but just a tiny spectrum for UVA. Titanium dioxide is therefore less effective against long UVA rays (340-400nm). Therefore, there is reallyno such thing as a real sunblock. But sunscreen is nonetheless important protection for your skin.

Sunscreen: important means to protect your skin

I don’t want to give you the wrong impression: Using a sunscreen as a protection against sun is important. Just be aware that you also have to reapply it. But I always tell my patients, let’s be practical. Why are we talking about so many details when the first thing is that you should just start using it!

If you apply suncream on your face, décolleté and hands every day, after washing your face and afterapplying your day cream or serum – you do a much better job than you would do without doing it. Of course, if you really want to protect yourself, you have to reapply the suncream every 2 hours. This is surely ok on the beach, but nobody does it during a normal day. Most of my patients haven’t even applied suncream on a daily basis.

So, if you do apply suncream 365 day a year regularly, then you can think about more detailed protection. Wear a hat. And if you drive by car, why not use gloves to protect your hands from sun damage like age or sunspots?!

Start today to prevent skin ageing during a cloudy or sunny day. Because… you guessed it: The sun is always shining – otherwise, it’s night.

Does sunscreen prevent tanning?

Unfortunately not! But then, if you have read this article this far, of course, you already know that. And as we’ve learned, there is no sunblock and no sunscreen can prevent your skin from sending out its protection shields, the melanin, which causes you the tan.

But why do you ask?

Well, you’re probably asking because you want to get a tan and you’re afraid to use a sunscreen, fearing it will prevent your much-desired tan. But why the heck do you want a tan? Tanning means no more and no less then the first step of destroying your skin cells… not really so desirable, is it?

Sun Protection: What does SPF mean?

SPF is the short form for Sun Protection Factor. You read that on all the packages, of course. The only rule most people generally follow ist: “The higher the number, the better.” Which is only partially true.

A lot of my patients come to me saying they finally found a SPF 100 and are so happy that finally they are 100% protected! Unfortunately, that’s not how it is. Because if you have a look at the SPF and the protecting graph, you will see it is not a linear graph. The SPF curve is a negative exponential graph. What does that mean?

SPF 30 takes away 97% of the UVB light. The SPF 60, on the other hand, is protecting you from 98%. Hence, it is just 1% more. Diffenently speaking, an SPF 30 is totally enough, it’s protection is not really weaker than a SPF of 50. Therefore, a SPF 100 is just misleading the consumer.

The SPF indicates how long you can stay out in the sun without getting a sunburn. But I just said that it’s UVB (not UVA) that gives you a sunburn, right? And, yes, that means that the SPF is only referring to UVB and not to UVA light!

Different forms of sunscreen

Oh, these times… you get sunscreen in almost any form you could possibly desire – sunscreen powder, sunscreen sticks, sunscreen spay, yes, even sunscreen wipes! Plus you have the choice between all sorts of different sunscreen brands, from cheap no-name brands to the expensive big names. Let’s go through the most important sunscreen options you find in a drug store, aside from traditional creams and gels:

  • Sunscreen sprays. They look so easy and fun to use. But sorry guys i have to disappoint you. First sunscreen sprays can even cause problem when inhaled. Second sunscreen sprays are never as protector as lotions or cream s or gels as you never ever apply the right amount of sun filters on your body. So it sounds too good to be true. Sorry to disappoint you.
  • Sunscreen sticks. I love them a lot. But be careful if you are suffering from acne or pimples. Why you should be careful with sun sticks? Because hey are very fatty. If you apply fat on a skin who tends to get pimples quiet quick you enhance the bacterial grow by creating a kind of tend for them. Read my article about acne to get better informed what to avoid what to use while suffering from acne.
  • Sunscreen powder. It is a nice add-on, but not a stand-alone option. Why? just imagine how much powder is left over on your faceat the end of the day. The sunscreen powder is just staying on top and can be rinsed and wiped off to quick. Therefore be careful and consider to use it on top of your normal sun protection gel or cream.

How much suncream do I need to use and how long does it last?

This is a very important question. In a lot of medical papers, it is clearly indicated that we should apply almost 2.00 mg/cm2. This amount should be the rough equal of 2 pumps from a pumping suncream or 2 full table spoons for the whole face. Which is a lot – and unfortunately nobody is applying it. You also should reapply it every 2 hours – and add additional protection like hats, clothing and shades for maximum protection.

Sunscreen ingredients: Staying safe

Sunscreen ingredients recently became a big topic. Some sunscreens have been found to contain ingredients that can be damaging to the body, even cause cancer – something it should actually prevent us from. Therefore, a lot of people are looking for sunscreens without oxybenzone and other potentially damaging ingredients. It really is a bit of a catch-22. On the one side, we want to have good filters as we want to protect us from skin damage like

  • skin cancer and
  • skin sun damage, such as as pigmentation (dark spots), rednesses and wrinkles.

But on the other side, we also want to use safe filters.

If we choose filters which stay on top of our skin, then they work as reflectors and we stay white. But nobody of us wants to look like a geisha every day. The typical reflectors are zinc dioxide and titan dioxide. But they do make us look whitish. If we use sunscreen filters that penetrate a little bit into the skin, we have to make sure that they just stay on the superficial layers and don’t go into our blood system.

So it became some sort of a “race” among the companies to develop great filters and make using suncream fun again, without getting this fatty greasy feeling.

Great sunscreen ingredients are sunscreen filters that are safe. These are are filters like:


Sunscreen filters with


however, should be carefully used and maybe replaced by products with the above mentioned suncreen ingredients.

(And don’t worry, you don’t have to memorize these terms. Just print them out or copy them and double-check next time you shop for sunscreen.)

What is the best sunscreen for sensitive skin?

The best sunscreen for sensitive skin in general as well as the best sunscreen for a face with sensitive skin are sunscreens that do not contain the following sun filters:


They are the same ones I mentioned above as to be use with caution. These sunscreen filters are in discussion to be hormone-active and some of these UV filters could actually cause allergies.

Allergy against sunscreen 

Sunscreen allergies are not so uncommon. But most of the time it is not a real allergy, it is rather a reaction of the skin with some ingredients inside a cream or perfume, activated through the heat of the sun. In other words: In your daily activities, you might not feel it, but as soon as the sun heats the skin, a reaction is started. You can once again compare it with the Bunsen burner in your chemistry session: Without heat – no reaction. So sometimes, it is just the normal sweat with your own perfume or with some creams, that are activated to cause a blister or an itchy reaction of your skin while in the sun.

Tips to avoid sun allergies

    • Never wear your perfume directly on your skin. Rather put it on your clothes.
    • Try to use a sunscreen gel rather than a heavy cream.
    • Try to avoid sunscreen with sunscreen filter ingredients like homosalate or octocrylene.


Best siunscreen for tattoos

A lot of people have tatoos these days, and I get a lot of questions aout how to protect it from fading when it’s exposed to sunlight. In order to keep your tattoo beautiful as lon as possible, always apply a sunscreen on your tattoo. It doesn’t need that much special treatment. Use a sunscreen with at least an SPF 30 with an extra UVA filter laser. Just with a sunscreen you can prevent your tattoo to fade in the sunlight. So, you’re actually doing something good for your skin and your tattoo at the same time.

How to use sunscreen under make-up

The best sunscreen to use under the make-up is a sunscreen which is very light. Therefore, look out for a lotion or a gel rather than a sun cream or ointment. Apply the suncream after washing your face. These are the steps you should take before you apply your make-up:

  • Wash your face.
  • Apply a light antioxidant serum with Vitamin C, resveratrol or green tea.
  • Apply your sunscreen gel.
  • Finally, apply your make-up.

Windows and shadow: Do they provide protection me from UV sun light?

Again, it depends on which UV light we’re talking about. You are not getting a sun tan or a sun burn inside the house or inside your car or in your office. But as we learned, UV-A does penetrate the window glass. So if you are lazy with sun cream, be careful. UV-A coming though the glass reaches your skin in the deeper layers, there destroying your collagen and causing you wrinkles, redness and a lot of pigmentation (these dark spots you do not like) in your face. So: Yes, use suncream even inside your house and office.

If you are sitting under a umbrella you might be protected from the UVB light and therefore you do not get tanned or a sunburn. But, unfortunately, UVA light goes through. Hence, you can get pigmentation and wrinkles. UVA is so rich in energy that an umbrella or a sun hat with translucent material is not protecting your skin from the damage UVA is causing.

Therefore: Please choose “real” protection. What does it mean? Choose shadows from beton (houses), trees etc. Or wear sun protection garments and a sunscreen.

Key Advice to share with your friends

So, guys, you see: There is so much to know about sun protection and sunscreen!

It is just extremely important to prevent premature ageing and wrinkles through sun UVA, but also to significantly reduce your risk of developing skin cancer. And this is my advice in a nutshell – please feel free to share it with your friends!

  • Wear sunscreen every single day. In the shadow. In the office. Everywhere.
  • Use sunscreen with an SPF 30, maximum 50.
  • Wear special sun protection clothes.