Dermatologists reveal ultimate guide to SPF – from how much to use to gravest mistakes

Skincare experts have revealed the biggest mistakes people are making when it comes to their sunscreen application.

Even though you should be wearing it year round, FEMAIL has asked a team of experts, including dermatologists and an esthetician, to share their best sunscreen tips ahead of summer.

They have also weighed in on the minimum SPF you should be using daily whether you’re indoors or outdoors, how often you should be reapplying, and the application amount you should be using on your face and body.

When shopping for sunscreen, the experts say people should make sure their sunscreen is broad spectrum and has an SPF of at least 30.

Brands describe a product as ‘broad spectrum’ when it protects against both UVA and UVB rays from the sun.

According to the Skin Cancer Foundation, UVB rays can cause sunburn and play a role in the development of skin cancer, while UVA ones lead to skin damage along with aging and wrinkles.

SPF stands sun protection factor and it’s a measure of how long it would take the sun’s UV radiation would take to redden your skin compared to the time when you’re not wearing sunscreen.

To avoid harm, follow our experts’ advice below to make sure you’re getting the best protection and what you should be looking for when making a sunscreen purchase.

What is the minimum SPF people should be using on a day-to-day basis?

Dr. Mona Gohara, who practices at the Dermatology Physicians of Connecticut and is an EltaMD board member, cited the American Academy of Dermatology who recommend a broad-spectrum SPF of 30 or higher.

She said this was regardless of weather conditions or skin type.

‘Remember that indoor lights, computer screens and cell phones can cause skin damage,’ Dr. Gohara told DailyMail.com.

And it doesn’t matter if you’re inside either, according to board-certified dermatologist Dr. Elizabeth Hale, who is senior vice-president of the Skin Cancer Foundation and chief medical advisor to sunscreen brand Vacation.

‘Even if you’re working from home inside, UVA rays penetrate through windows, or you’ll end up running outside for a quick errand,’ she said.

‘Remember that indoor lights, computer screens and cell phones can cause skin damage,’ dermatologist Dr. Mona Gohara told DailyMail.com (stock image)

‘That being said, if you’re staying inside for the majority of the day you don’t need to reapply as often; a liberally-applied base coat is enough.’

Esthetician Joanna Czech – who counts Jennifer Aniston, Kim Kardashian and Hailey Bieber as clients – added she preferred using a maximum of SPF 35 for everyday use on the face because ‘higher SPF can cause skin reactions.’

‘Also, don’t forget your ears, hands, feet, soles of the feet, and lips, a mistake many people make,’ she said.

Czech also advised people should avoid mixing their SPF with other products, such as foundation or moisturizers, because it would affect its efficacy.

‘The SPF also needs to create an even shield-type layer on your skin for maximum protection against the sun,’ she said.

‘SPF should be the last step in your skincare routine before you apply makeup.’

How often should people be reapplying their sunscreen?

Our experts are unanimous on this advice: every two hours.

‘When you’re outside or on the beach, try to reapply your sunscreen every two hours – and even more often if you’re sweating, swimming, or toweling off,’ Dr. Hale explained.

‘You should also seek the shade whenever possible, and try to avoid the peak hours of sunlight (10AM – 4PM). When you are going to be exposed to the sun, in addition to applying (and reapplying) sunscreen, wear sun protective clothing, a wide brimmed hat, and sunglasses.’

But if ‘you’re truly indoors all day, it’s sufficient to apply an ample base coat in the morning,’ she told DailyMail.com.

‘Whenever you leave the office, whether it’s to run an errand or just take a quick walk around the block, you should reapply SPF ahead of time.’

Dr. Gohara also advised people to consider increasing the SPF of their sunscreen if they’re going to be experiencing ‘more intense UV exposure.’

And this reapplication guideline also applies to the sunscreen you put on your face in the morning.

For those not wanting to disturb their makeup, Dr. Hale recommends an SPF powder or face mist, like Vacation’s Super Spritz SPF 50.

How much sunscreen should be applied?

Czech recommends the two-finger rule, which should be sufficient to cover your face and neck.

Dr. Hale added the official guideline was two milligrams of sunscreen per square centimeter of skin, ‘but that can be hard to visualize.’

‘You can think of it as a shot glass full for your whole body, or a quarter-sized dollop for your face, neck, and chest to ensure complete coverage,’ she told DailyMail.com.

‘If you’re using a spray sunscreen, make sure you see an even sheen of product all over, and then rub it in with your hands.’

Esthetician Joanna Czech recommends the two-finger rule, which should be sufficient to cover your face and neck

Can the same product be used for face and the body – both in terms of formula and SPF?

The experts said people should make sure their sunscreen was broad spectrum and had an SPF of at least 30.

Dr. Gohara added you could use the same product for both the face and body.

But one might opt for a moisturizing formulation when it came to the face.

‘EltaMD UV Daily is a perfect example, or if they have inflammation on the face such as acne the may want an appropriate product such as EltaMD UV Clear which is made with a clear, lightweight texture and niacinamide to reduce irritation,’ she said.

‘In other words faces may require more nuanced consideration when choosing a product.’

Dr. Hale agreed people should be using broad spectrum sunscreen with SPF 30 or higher for both your face and your body. 

‘You can absolutely use the same formula from head to toe, however some people are more sensitive to products on their face. If that’s the case, sensitive skin tends to tolerate mineral formulas better, and look for products that are fragrance-free,’ she said.

And when it comes to shopping for the best sunscreen for you, Czech said there were two different types to watch out for: physical and chemical. 

‘Physical sunscreen will have key ingredients titanium dioxide and zinc oxide. Both ingredients create a protective barrier from the sun by sitting on top of your skin. This type of sunscreen is less likely to clog pores, as it doesn’t penetrate the dermis,’ the esthetician explained.

‘On the other hand, chemical sunscreen is absorbed into the epidermis. It is important to apply chemical sunscreens 30 minutes before exposing yourself to the sun giving it time to soak into the skin.

‘If you have acne-prone skin or sensitive skin, I would recommend a physical sunscreen.’ 

Dr. Gohara said people should also search for a sunscreen with a water-resistant formula and ‘choose brands… that are rooted in science around sun care.’

And for those with dry skin, Dr. Hale recommended looking for ‘hydrating non-actives that deliver hydration to the skin such as niacinamide or hyaluronic acid.’

How to treat sunburn symptoms

‘I have to caveat this with the obvious: try your best to avoid a sunburn in the first place,’ Dr. Hale said.

But if the worst should happen, the dermatologist advises removing yourself from the sun immediately.

‘For any pain, an NSAID can help with the inflammation that comes from a sunburn. Then apply a product like Vacation’s After Sun Gel, which is a really soothing aloe vera-based product that helps to cool the skin down,’ she said.

‘Make sure to keep your skin well moisturized, because skin that’s hydrated repairs more easily. If you’re still experiencing pain, a homeopathic remedy you can try is to apply cold milk compresses; just make sure it’s not skim milk, since it’s the fat and proteins in milk that are soothing to damaged skin.

Keep your skin hydrated and continue using sunscreen after you get sunburned, the experts advised

‘Finally, make sure to tell your dermatologist if you get a sunburn, because it directly increases your chance for skin cancer.’

Dr. Gohara added: ‘Wear sunscreen with any additional exposure, stay out of the sun if possible… and anti-inflammatories topically or orally if need be.’

As for the maximum amount of time people should spend in the sun even when wearing sunscreen: ‘There is no number here, the idea is simply to protect yourself with clothing, SPF, and shade when possible.’

Are tanning oils ever OK to use?

Dr. Hale said oils were OK to use as long as they had at least an SPF of 30.

‘You can use them as you would any other sunscreen. Just make sure if the formula is not water-resistant, to reapply immediately if you’re sweating or exposed to water,’ she told DailyMail.com.

‘Some people simply prefer oils, and I’m so glad that the days of “tanning oils” are mostly behind us.’

Any other sun protection tips?

Czech also warns people about heat-induced hyper-pigmentation. 

‘While it is known that the sun can cause hyperpigmentation, heat induced hyperpigmentation is also something to keep in mind during the warmer months,’ she said.

‘SPF does a great job protecting you from the sun but it does not protect against the heat. I recommend The Cream from my skincare line which contains a unique tetrapeptide defense that protects your skin from the heat-induced hyperpigmentation.’