Participants will be invited to take part in a research study as they have been diagnosed with multiple actinic keratosis lesions (AK). AK usually present as small, rough, dry, scaly and/or crusty patches or papules of the skin that can be skin-coloured pink, red, tan or a combinationof colours and are often easier to feel than see at their earlier stages. AK are commonly diagnosed in adults, particularly in patients aged 45 years and older and are considered to be pre-cancerous lesions.

The research is aiming to investigate the protective effect of an investigational sunscreen known as Anthelios Fluide 100 KA+ UVMune 400, when used together with good sun protection habits (which include staying in the shade during the hours of 11 am and 3 pm, wearing sun-protective clothing, wearing a wide-brimmed hat) in participants with multiple Actinic keratoses's.

Eligible participants will be randomly assigned into 1 of 2 groups - an intervention or control group The study main objective is to evaluate tested sunscreen prevention on actinic keratosis lesions.

Inclusion Criteria:

1. Adult outpatients ≥ 60y old with at least 11 clinically typical actinic keratosis lesions, including at least one on the face;
2. Patient having understood and signed a written informed Consent Form to participate in the study indicating the potential participant's willingness to undergo the study procedures and complete the study.

Exclusion Criteria:

1. Atypical actinic keratosis lesions including suspected squamous cell carcinoma and basal cell carcinoma (could be present at screening and treated but cannot be present at 1st visit);
2. History of >2 squamous cell carcinomas;
3. Known history of immunodepression whatever its cause in the past year;
4. Participants who cannot undergo skin biopsies, with a history of scarring problems or who have developed adverse effects from the use of local anesthesia will also be excluded.
5. Participant using interferon or interferon inducers, immunomodulators, cytotoxic or immunosuppressive drugs, corticosteroids, retinoids, other keratolytics or have received investigational drug within 4 weeks before enrolment
6. Participant having active, localized or systemic infection other than the AK lesions
7. Participant having any dermatological affection within the treated and adjacent area according to the Investigator judgement
8. Participant having a present or past skin condition that according to Investigator judgment, deems inappropriate for study participation
9. Participant having other significant medical conditions that according to Investigator Judgment, deems inappropriate for study participation
10. Participant having a known hypersensitivity, allergy or contraindication to any ingredients contained within the cosmetic products,
11. Participant taking part or intending to take part in another study for 30 days prior to D1 visit, and 30 days following last study visit. that according to Investigator judgment, deems inappropriate or may interfere for study participation
12. Participant using light-based devices such as but not limited to PUVA (Psoralen Ultraviolet A therapy), IPL (Intense Pulsed Light), laser, LED (Light Emitting Diode) devices or tanning beds, within 4 weeks before enrolment.
13. Participant having applied any topical product on the investigational areas the day of enrolment visit,
14. Participant under legal guardianship or incapacitation.
15. Participant being psychologically incapable of signing informed Consent Form and unable to comply with the protocol requirements according to investigator judgment.