Choosing a sunscreen shouldn't depend on the SPF alone. Two sunscreens can have the same protection factor and yet be formulated very differently. One might be designed for sensitive skin, while another may include filters or perfumes that perhaps don't suit you.
Learning to read the ingredient list helps you distinguish whether a sunscreen is mineral, chemical, or mixed, to recognize filters like Zinc Oxide, Titanium Dioxide, or Octocrylene, and to detect important signs like the [nano] symbol, the PAO, or the presence of fragrances.
In this guide, you will see how to interpret a sunscreen label step-by-step, without unnecessary technical jargon and with practical criteria for making better choices.
What is the INCI of a sunscreen
INCI stands for International Nomenclature of Cosmetic Ingredients. It is the list of ingredients that appears on the packaging and reveals which solar filters the formula uses, whether it contains perfume, if it uses nanoparticles...
The INCI is the international system used to name the ingredients in cosmetic products. Thanks to this system, a sunscreen sold in Spain, France, or Germany uses the same technical names to identify its ingredients. This allows you to compare products, recognize solar filters, detect allergens, and better understand what you are applying to your skin.
In a sunscreen, the INCI is especially important because UV filters are the ingredients that determine how the product protects against the sun. Looking at the front of the packaging is not enough. Words like "mineral," "natural," "sensitive skin," or "ocean-friendly" can be a guide, but the most reliable way to check the formula is to review the list of ingredients.
Where to find the INCI on a sunscreen
The INCI usually appears on the back of the packaging, on the base of the tube, or on the outer box, preceded by the word Ingredients.
In an online store, it should also appear in the product information sheet. If a brand does not show the full list of ingredients clearly, it is a sign of poor transparency. For cosmetic products, and especially for sunscreens, the consumer should be able to review the formula before buying.
How to read the INCI
How ingredients are ordered in the INCI
The first rule worth remembering is that the ingredients in the INCI are listed in descending order of concentration. This means that the first ingredients are those present in the highest proportion.
The INCI order helps to read the claims on the packaging with more judgment. If a sunscreen highlights "with aloe vera" or "with hyaluronic acid" but that ingredient appears almost at the end of the list, it is likely present in a low concentration. This does not necessarily mean it contributes nothing, but it does allow for a better understanding of what real weight it has within the formula.
However, there is an exception to keep in mind: ingredients present at less than 1% can appear in any order at the end of the INCI. For this reason, the list does not allow you to know the exact concentration of each ingredient, but it does serve as a guide.
What the most important symbols on a sunscreen mean
Before getting into the filters, it is helpful to understand some basic elements of the label.
| Label element | What it means | Why it matters |
|---|---|---|
| SPF | Indicates protection against UVB rays | UVB are the main cause of sunburn |
| UVA in a circle | Indicates minimum UVA protection relative to SPF | UVA penetrates deeper and is associated with photoaging |
| Broad spectrum | Protection against UVA and UVB | Important for complete sun protection |
| PAO, e.g., 12M | Recommended use time after opening the product | 12M indicates 12 months from opening |
| Water resistant | Indicates resistance for a limited time | Does not mean you don't need to reapply |
| INCI | List of ingredients | Lets you know which filters and other ingredients it contains |
SPF primarily indicates protection against UVB rays, which are those that cause sunburn. However, it does not inform you by itself of the total protection against UVA rays, which are related to skin aging, spots, and deep skin damage. For this reason, in addition to SPF, it is advisable to look for indications of UVA protection or broad spectrum. A well-chosen sunscreen should protect against both types of radiation.
How to know if a sunscreen is mineral or chemical by reading the INCI
In a sunscreen, UV filters usually appear among the first ingredients because they are an important part of the formula. That is why the beginning area of the INCI is the most important for knowing what type of protector you are buying.
Mineral filters are recognized by two main names:
| Name in the INCI | Common name | Type of filter |
|---|---|---|
| Zinc Oxide | Zinc oxide | Mineral |
| Titanium Dioxide | Titanium dioxide | Mineral |
If you find Zinc Oxide, Titanium Dioxide, or both among the main ingredients, the sunscreen contains mineral filters. If there are also no chemical filters in the list, you are looking at a mineral sunscreen.
Common ingredients in sunscreens and their functions
| Type of ingredient | Examples in the INCI | Function |
|---|---|---|
| Aqueous base | Aqua | Main vehicle |
| Emollients | Caprylic/Capric Triglyceride | Help to soften and nourish |
| Humectants | Glycerin, Sodium Hyaluronate | Help retain moisture |
| Silicones | Dimethicone, Cyclopentasiloxane | Improve texture and spreadability |
| Soothing agents | Panthenol, Aloe Barbadensis Leaf Juice, Niacinamide | Can help calm and reinforce the skin barrier |
| Antioxidants | Tocopherol, Tocopheryl Acetate | Help protect the formula and provide antioxidant care |
| Preservatives | Phenoxyethanol, Benzyl Alcohol, Benzoic Acid | Prevent microbiological contamination |
| Fragrance allergens | Limonene, Linalool, Geraniol, Citronellol | Indicate presence of perfume or aromatic components |
If you find filters like Benzophenone-3, Octocrylene, Homosalate, or Ethylhexyl Methoxycinnamate when reading the INCI, it is worth reviewing in more detail why they raise concerns. You can find more information in our guide on 8 ingredients in your sunscreen you should avoid and what to use instead
What "nano" means in the INCI of a sunscreen
Nanoparticles are used in mineral sunscreens to improve texture and reduce white residue. Being smaller particles, they allow the product to spread better and feel lighter. On intact skin, these nanoparticles are considered safe under normal conditions of use. However, they spark debate regarding their environmental impact and the danger of inhalation.
In spray or powder formats, nanoparticles could be inhaled, especially if they contain titanium dioxide, which is why it is advisable to be cautious with these types of presentations. Additionally, in marine environments, it has been suggested that very small particles of zinc oxide or titanium dioxide could interact with aquatic organisms if they reach the water in large quantities.
Therefore, if you are looking for a more cautious option for the beach, for family use, or to reduce the impact on marine ecosystems, you can prioritize non-nano or non-nano formulas. This detail usually appears on the packaging or in the product info sheet, but it is always best to confirm it in the brand's information.
