Summer Skincare Tips by Expert Custodio d’Avo: How to Protect the Skin Barrier & Avoid Harmful Ingredients
Dehydration, breakouts, sunburn, and sensitivity — summer brings a whole new set of skincare challenges. While many are diligent about applying SPF, fewer truly understand how to protect the skin barrier, avoid irritants, and select the right ingredients for warm-weather conditions.
We sat down with Swissline Brand Director Custodio d’Avo, a skincare expert with decades of experience in cosmetic science and product innovation, to uncover the best ways to keep your skin healthy, balanced, and radiant all summer long.
In this interview, you’ll learn:
- The #1 mistake most people make with sunscreen
- Which ingredients to avoid in summer skincare
- The best barrier-repair and anti-inflammatory ingredients
- A full Swissline summer skincare routine
- How to calm redness, boost hydration, and stay glowing
Meet the Expert: Custodio d’Avo
With over 20 years in the skincare industry, Custodio leads product development at Swissline. Drawing on a rich legacy of Swiss cellular skincare, he combines scientific insight with a passion for long-term skin health — especially when it comes to barrier protection.
Q: What are the top summer skincare concerns you see — and how should we address them?
"Number one summer concern should be UV stress: longer hours under the sun, intense sun under bright blue skies, and more outdoor time... including actual tanning and sunbathing. What people tend to overlook is that the amount of sunscreen applied matters just as much as the SPF number. We all rely too much on the SPF indicated on the tube, but that number only means something if you apply enough of it.
Also, even in summer, we should still be thinking skin barrier — big time"
Q: Why is the skin barrier more vulnerable in summer — and how can we protect it?
"Sun exposure, saltwater, chlorine… they’re all enemies of the skin barrier. But let’s remember, skin isn’t a static wall made of bricks and mortar — it’s a dynamic, living organ in constant negotiation with the environment. The barrier function is a trade-off; we give and take — moisture, pH, biome, lipids.
To protect the skin barrier, we need to give back not just moisture, but also skin-identical factors that help retain it longer. And of course, antioxidants. Very important also: addressing inflammation. This is why we say at Swissline that at least one Age Intelligence serum should be part of any summer routine — they’re designed precisely to reduce inflammation."
Q: Which ingredients should we avoid in summer due to increased sun sensitivity?
"Top of the list: glycolic acid — especially during the day. It’s not the right time for that. Products high in alcohol or heavily fragranced with essential oils are also problematic. These are highly photosensitizing and allergenic year-round, but exposure to sun makes things worse."
Q: What are the best ingredients to strengthen the skin barrier and prevent sun damage?
"All ingredients that go under skin’s own NMF (Natural Moisturizing Factors): amino acids, ceramides, squalane, cholesterol, urea…
But also ingredients that fight inflammation: derivatives from centella asiatica as Madecassoside (the Rolls Royce amongst all options), panthenol, bisabolol, licorice derivatives… you will find them all in Age Intelligence formulas."
Q: What’s the ideal Swissline summer skincare routine for hydration and protection?
Discover the core summer routine under Kits & Gifts — each set offers better value than buying the products individually.
- One of the Age Intelligence cleansers – foam or non-foam, whichever suits your skin.
- Then follow with the Pore-Reducing Water (great choice for the summer unless you are super dry, in which case Good Water is better). These are great essence-waters without any alcohol, full of antioxidants and NMF factors.
- Your main product should be Pro-Recovery Serum (unless you tend toward oiliness, then I’d go for the Essential Serum), to protect the skin barrier and lower inflammation.
- During the day finish with the Never-Seen Sunscreen. At night, use one of the Smart Cream textures that best suits your skin: Mat, Universal or Rich."
Q: How does Swissline address summer-specific skin stress with its formulations?
"Keeping alcohol out, keeping allergens from fragrance out, keeping essential oils out, keeping mineral oils out: NMFs, anti-inflammatories, ATP, and a powerful mix of skin-identical antioxidants like SOD and glutathione."
Q: What’s one common mistake people make with SPF or sun protection in their routine?
"Applying too little, often because they have already applied too much moisturizer before! This is the reason why at Swissline we favor “hybrid” sunscreens which can double as moisturizer and be applied alone after a serum. So that one can comfortably apply more of it. Need a richer moisturizer because your skin is drier? Apply it nighttime!
Another common mistake: relying on tinted SPF or makeup with SPF. Because these are pigmented, people apply just a thin layer to keep things looking natural — but that cuts protection way down. An SPF 50 tinted product can easily perform like SPF 15 if applied too lightly. The right way is to apply a proper, invisible SPF 30 or SPF 50 first, then use the tinted product on top, just as you would a makeup or BB cream"
Q: What’s your #1 summer skincare tip for keeping skin healthy, radiant, and calm?
"One tip I haven’t seen mentioned yet, and one I personally swear by, is starting your summer mornings with a hydrating, energizing, anti-redness mask. Something like the Age Intelligence Hydraholic Mask is perfect to apply as soon as you wake up. Think of it as a quick home-spa ritual that tells your skin it’s summer, you're relaxed, and you’ve got a little extra time to care for yourself. It’s the perfect way to compensate for shorter skincare routines and less product layering during warmer months, while your skin is more exposed to the sun. Let that daily morning mask show the love to your skin. 😉"