Sunscreens

Types, composition and correct use to ensure safe sun protection

Summary in 60 seconds

• A “sunscreen” is a product that forms a film on the skin to reduce the impact of ultraviolet (UV) radiation.
• There are organic filters (often called “chemical”) and inorganic filters (often called “mineral”, mainly zinc oxide and titanium dioxide).
• SPF is primarily related to UVB (sunburn/erythema). For everyday use, also look for UVA («broad spectrum»).
• The real effectiveness depends more on choosing one that you tolerate and applying enough and reapplying when necessary.
• Solid sun protection combines: shade + clothing + hat + sunglasses + sunscreen . The WHO reminds us that sunscreen should not be used to «extend» sun exposure. World Health Organization 2022

What is UV radiation and why does it matter?

Solar radiation includes UVA (longer wavelengths) and UVB (shorter wavelengths). Simply put: UVB is primarily associated with sunburn; UVA contributes to photoaging and is also important in overall UV risk. Therefore, a good sunscreen should protect against both UVB and UVA rays , not just have a «high SPF.» (European Commission 2006)

No filter is perfect: there is no such thing as «total blockage,» and effectiveness drops significantly if too little is applied. European Commission 2006

How does it work? (simple explanation, no complicated physics)

A sunscreen protects primarily through two mechanisms:

1. UV energy absorption (mainly in organic filters):
   Molecules designed to absorb UVA/UVB rays and transform that energy into less harmful forms (e.g., heat). The «family» and combination of filters defines the range of protection (more UVB, more UVA, or broad spectrum). Nitulescu 2023

2. Particle attenuation (inorganic/mineral filters):
   Primarily zinc oxide (ZnO) and titanium dioxide (TiO₂) . Together, ZnO provides better UVA+UVB coverage , and TiO₂ typically performs very well against UVB ; this is why they are frequently combined. Schneider 2019

In modern practice, most «serious» products are blends : they combine filters to achieve broad spectrum, good stability, and a pleasant texture.

Types of filters (active) and their differences: advantages and disadvantages

1) Organic filters (often called “chemical”)

What they are: organic molecules that absorb UV light. Common examples (may vary by country): avobenzone, octocrylene, octisalate, homosalate, octinoxate, oxybenzone, among others; in some markets, there are «new» broad-spectrum filters with high photostability. Latha 2013

• (usual) advantages
• • Lighter and more transparent textures (less «white halo»).
  • Highly versatile for fluids , gels and invisible finishes .
• (Possible) Disadvantages
• • In some people they may sting or irritate the eyes (it depends on the formula, not just the filter).
  • Photostability varies: some filters require combinations/stabilizers to maintain performance over time. Nitulescu 2023

2) Inorganic/mineral filters (ZnO and TiO₂)

What they are: mineral particles that attenuate UV (by absorption and scattering).

• (usual) advantages
• • Good tolerance on reactive skin; they often sting less in the eyes.
  • ZnO is especially useful when you’re looking for broad UVA coverage. Schneider 2019
• (Possible) Disadvantages
• • They may leave a whitish residue (improved with dyes/pigments and with formulation).
  • In spray/aerosol format, there is concern about the inhalation of particles , so caution is advised and it should be avoided, especially on the face and in young children. Schneider 2019

3) “Hybrids” and combinations

What they are: Many sunscreens combine organic and mineral ingredients to:

• • Expand UVA/UVB spectrum
  • Improve stability
  • Optimize cosmetics (less whiteness, less oil)
  • Facilitate adherence to daily use

4) With color (tinted) and visible light: when it makes sense

For some people with melasma or a tendency toward hyperpigmentation, the visible light component may matter. In those cases, tinting with iron oxides (in addition to SPF and UVA protection) is often recommended. American Academy of Dermatology 2023
In studies, formulas with iron oxides have shown better protection against visible light-induced pigmentation than untinted versions. Dumbuya 2020

Composition: what’s «besides the filter» and why it matters

Performance and tolerance depend on both the active ingredient and the vehicle (base). In addition to UV filters, the following are typically listed on a label:

• Emollients and moisturizers: provide comfort, reduce tightness.
• Film formers: help the product «stick» and resist sweat/water.
• Emulsifiers, thickeners and silicones: determine texture (cream, fluid, gel).
• Alcohols (in some fluids): lighten the sensation; on skin with eczema they can be irritating.
• Fragrance and certain preservatives: these can be problematic if you are very sensitive.

Practical rule: if something “burns” or triggers breakouts, it is not a personal failure: it is a sign to adjust the formula (for example, fragrance-free, more cream, mineral or hybrid).

Presentations (formats) and how to choose according to your real life

• Cream/lotion: versatile for body, normal to dry skin.
• Fluid/gel: useful for combination-oily skin or humid climates (lighter feel).
• Stick/bar: excellent for small areas (nose, cheekbones, eye contour) and touch-ups.
• Spray/aerosol: convenient, but easy to run out of if you apply too little or unevenly; avoid inhalation and do not use it as a direct «mist» on your face. If you do use it, apply generously and spread with your hand . Schneider 2019
• Powder with SPF: can help with cosmetic touch-ups, but is not ideal as the sole protection for foundation.

How to choose and how to use it? (concrete steps)

Step 1: Choose the “minimum effective” for the majority

• SPF 30 or higher for regular sun exposure; for high exposure (beach, mountains, sports), it is usually reasonable to increase and reinforce physical sun protection measures. The WHO recommends SPF ≥30 for exposed skin. World Health Organization 2024
• Look for broad spectrum (UVA/UVB). In the U.S., «Broad Spectrum» requires a «critical wavelength» test ≥370 nm. FDA 2012
  In the EU, it is recommended that UVA protection be at least 1/3 of the SPF and also a critical wavelength of 370 nm . European Commission 2006

Step 2: Choose a texture that you will actually use

• The “best” sunscreen is the one you can apply every day you need it , in sufficient quantity, without hating it.

Step 3: Apply a sufficient amount (to the area that fails the most)

• SPF is measured using a standard amount (approx. 2 mg/cm² ). If you apply less, the protection drops more than you might think. European Commission 2006
  A simple guideline for face/neck is the two-finger rule (two lines of product on your index and middle fingers) to approximate that dose. Taylor 2002

Step 4: Reapply when appropriate

• When outdoors, reapply every 2 hours , and more frequently if you swim, sweat, or towel dry. American Academy of Dermatology 2025

Step 5: Integrate good practices (the “non-cosmetic” part)

• Avoid the intense midday sun; seek shade, wear clothing, a hat, and sunglasses. World Health Organization 2022
• Don’t use the filter as an excuse to «stay longer.» The WHO is explicit on this point. World Health Organization 2022

Step 6: Children and babies (prudent summary)

• Children under 6 months : prioritize shade and clothing ; if sun cannot be avoided, use may be used in small areas according to health recommendations. FDA 2024
• In children: choose broad spectrum, adequate SPF, and reinforce with physical measures. American Academy of Pediatrics 2026

Common mistakes when applying sunscreen

• Apply “a thin layer” (underdosing).
• Forget ears, neck, décolletage, hands, insteps and scalp (if there is low hair density).
• Rely only on makeup with SPF for a full morning outdoors.
• Do not reapply at the beach/sports venue or after sweating.
• Choosing a texture you dislike and ending up only using it halfway.
• Use spray as if it were perfume, without spreading.
• Thinking that “very high SPF” is equivalent to invulnerability.

Myths vs. Facts

• Myth: “It blocks 100%.”
  Fact: there is no total protection; moreover, actual use is usually less than laboratory use. European Commission 2006

• Myth: “If it’s mineral, it’s always better for everyone.”
  Fact: It depends on tolerance, texture, and whether you actually use it properly. Mineral oil can be excellent, but it’s not automatically superior.

• Myth: “With a high SPF I don’t need to reapply.”
  Fact: Reapplication remains key, especially outdoors. American Academy of Dermatology 2025

• Myth: “Dark skin doesn’t need sun protection.”
  Fact: Darker skin burns less, but it is not immune to photodamage or hyperpigmentation; the strategy is adjusted, not omitted.

Frequently Asked Questions

Which is better: chemical or mineral?

• There’s no single «best» option. If eye irritation occurs or you have very reactive skin, a mineral or hybrid oil might be better. If you hate the heavy feel or white residue, a modern organic oil can help you stay consistent. The key is broad spectrum plus correct use .

SPF 30 or 50?

• Both can be suitable if applied correctly. Increasing from 30 to 50 offers incremental improvement, but it doesn’t compensate for applying the wrong amount or not reapplying.

How much should I use on my face?

• As a practical guide: two lines on two fingers for face and neck (adjust according to face size and texture). Taylor 2002

How often should I reapply?

• Outdoors: every 2 hours , and more frequently if there is water, sweat, or a towel. American Academy of Dermatology 2025

Do spray filters work?

• They can be effective, but they are easily misused. Avoid inhaling, do not spray directly on the face, and spread with your hand ; extra caution is advised with children. Schneider 2019

I have spots or melasma: what should I look for?

• In addition to broad spectrum, tinting with iron oxides for visible light is often helpful. American Academy of Dermatology 2023

And what about vitamin D?

• If you’re worried, it’s best to talk to your doctor: vitamin D can be obtained through diet and supplementation when appropriate, without «prescribing» burns or intense exposure.

Bibliography and sources

• European Commission. Commission Recommendation of 22 September 2006 on the efficacy of sunscreen products and the claims made relating thereto . Official Journal of the European Union. 2006;L265:39-43.
• World Health Organization. Ultraviolet radiation [Internet] . Geneva: WHO; 2022 Jun 21 [cited 2026 May 29] .
• World Health Organization. Radiation: protecting against skin cancer [Internet] . Geneva: WHO; 2024 Jul 16 [cited 2026 May 29] .
• American Academy of Dermatology Association. How to apply sunscreen [Internet] . Rosemont (IL): AAD; updated 2025 Aug 15 [cited 2026 May 29] .
• US Food and Drug Administration. Labeling and effectiveness testing: sunscreen drug products for over-the-counter human use — small entity compliance guide [Internet] . Silver Spring (MD): FDA; 2012 Dec [cited 2026 May 29] .
• US Food and Drug Administration. Should you put sunscreen on infants? Not usually [Internet] . Silver Spring (MD): FDA; updated 2024 May 9 [cited 2026 May 29] .
• American Academy of Pediatrics. Sun protection: what parents need to know [Internet] . Itasca (IL): American Academy of Pediatrics; 2026 Jan 15 [cited 2026 May 29] . doi:10.1542/peo_document044.
• Schneider SL, Lim HW. A review of inorganic UV filters zinc oxide and titanium dioxide . Photodermatol Photoimmunol Photomed. 2019;35(6):442-446. doi:10.1111/phpp.12439.
• Taylor S, Diffey BL. Simple dosage guide for suncreams will help users . BMJ. 2002;324(7352):1526. doi:10.1136/bmj.324.7352.1526/a.
• Latha MS, Martis J, Shobha V, Shinde RS, Bangera S, Krishnankutty B, et al. Sunscreening agents: a review . J Clin Aesthet Dermatol. 2013;6(1):16-26.
• Nitulescu G, Lupuliasa D, Adam-Dima I, Nitulescu GM. Ultraviolet filters for cosmetic applications . Cosmetics. 2023;10(4):101. doi:10.3390/cosmetics10040101.
• Dumbuya H, Grimes PE, Lynch S, Ji K, Brahmachary M, Zheng Q, et al. Impact of iron-oxide containing formulations against visible light-induced skin pigmentation in skin of color individuals . J Drugs Dermatol. 2020;19(7):712-717. doi:10.36849/JDD.2020.5032.
• American Academy of Dermatology Association. Melasma: self-care [Internet] . Rosemont (IL): AAD; updated 2023 Sep 12 [cited 2026 May 29] .