Photoallergy test

Photoallergy testing is an essential clinical evaluation to determine whether a substance causes an allergic reaction after exposure to light (UV) .
This analysis is performed on human volunteers under medical supervision and according to strict ethical protocols. It aims to identify photosensitizing compounds likely to induce skin reactions when exposed to sunlight.

The photoallergy test is a key tool in validating the safety of cosmetic and sun care products , especially those containing plant extracts, perfumes, UV filters or colorants .

Principle and test protocol

The study involves applying a tested substance to the skin , followed by controlled exposure to UV-A or UV-B radiation .
The skin is then observed to assess local reactions (erythema, edema, pruritus).

The protocol typically includes:

1. Induction phase : repeated application of the product to a given skin area.
2. Irradiation phase : exposure to a calibrated light source.
3. Observation phase : delayed reading of skin reactions to distinguish photoallergy from simple phototoxicity.

Unlike the phototoxicity test , photoallergy involves a delayed immunological mechanism , requiring prior sensitization.

To complement this assessment, YesWeLab also offers:

• the phototoxicity test ,
• skin tolerance assessment ,
• and the study of light stability for photosensitive formulas.

Industrial applications

Photoallergy testing is particularly recommended for:

• Cosmetic products and sun care : validation of the safety of UV filters, perfumes, colorants, essential oils or botanical extracts.
• Plant-based active ingredients : identification of potentially photosensitizing molecules (coumarins, furocoumarins, bergapten, psoralen, etc.).
• Topical pharmaceutical products : control of photo-induced reactions related to excipients or active ingredients.
• Food supplements : securing photosensitive extracts intended for sun exposure.

The objective is to ensure the safe use of products exposed to light , while respecting European regulatory requirements (Regulation EC No. 1223/2009).

Analytical interest and complementarity

Photoallergy tests are part of a suite of safety and skin compatibility analyses used to evaluate the behavior of formulations under light exposure.
They are often associated with:

• photostability studies to verify the degradation of ingredients
• OECD 429 skin sensitization test ,
• the in vitro cytotoxicity test ,
• and the evaluation of thermal stability to characterize the overall behavior of the product.
• These combined tests ensure a complete characterization of the safety profile of formulations, from development to market launch.

YesWeLab Services

YesWeLab works with a network of partner laboratories accredited to ISO 17025 and/or COFRAC , specializing in toxicology, photobiology, and cosmetic clinical trials .
Our experts select the protocol best suited to your matrix, whether it's a raw ingredient, a cosmetic prototype, or a finished product .

Thanks to the YesWeLab digital platform , you can submit your analysis requests online, track your samples, and access your reports with complete transparency.
Since 2020, YesWeLab has been supporting cosmetic laboratories, sun care brands, and formulators in validating the tolerance and photo-induced safety of their products.

For any specific request or quote, contact our scientific team today.