This study aims to evaluate the effectiveness of a biophotonic cosmetic massage cream in reducing musculoskeletal foot pain in adults. Participants with pain in one or both feet attending the Podiatry Clinical Area of the University of Seville will be randomly assigned to receive either the investigational cream or a placebo cream with similar characteristics. The assigned product will be applied topically to the painful area twice daily for 10 consecutive days. Pain intensity, pressure pain threshold, foot function, and health-related quality of life will be assessed during the study.

Foot pain is a common and clinically relevant problem in adults, and musculoskeletal foot pain is frequently managed with oral and topical pharmacological treatments. However, conventional analgesic and anti-inflammatory therapies may be associated with adverse effects, which supports the investigation of potentially safer conservative alternatives. This study is designed as a randomized, placebo-controlled, parallel-group clinical trial to assess whether a biophotonic cosmetic massage cream can significantly reduce musculoskeletal foot pain in adults.

Eligible participants will be adults with musculoskeletal pain in one or both feet who attend the Podiatry Clinical Area of the University of Seville. Participants will be recruited consecutively in the context of routine clinical care and will be randomly assigned in a 1:1 ratio to either an experimental group receiving the biophotonic cosmetic massage cream or a control group receiving a placebo with similar characteristics.

The intervention consists of topical self-application of the assigned product to the painful area of the foot twice daily for 10 consecutive days, following instructions provided by the research team. The primary outcome will be pain intensity measured using the Numeric Pain Rating Scale (NPRS-11). Secondary outcomes will include pressure pain threshold measured with a Wagner FPK 10 pressure algometer, foot pain and function assessed with the Foot Function Index, and health-related quality of life assessed with the SF-12 questionnaire.

The planned sample size is 170 participants, corresponding to 85 per group, allowing for an anticipated 20% loss to follow-up. Statistical analyses will compare changes between groups and over time, with a significance level of 0.05 and analysis preferably following the intention-to-treat principle.

Inclusion Criteria:

• Adults aged 18 years or older.
• Patients attending the Podiatry Clinical Area of the University of Seville.
• Presence of musculoskeletal pain in one or both feet at the initial assessment.
• Ability to understand the study information and provide written informed consent.
• Ability to follow study instructions and complete study assessments.
• Intact skin at the application site.

Exclusion Criteria:

• Foot pain of non-musculoskeletal origin, or pain mainly attributable to infectious, vascular, tumoral, severe neurological, or decompensated systemic diseases.
• Wounds, ulcers, burns, dermatitis, skin infections, or any active skin disorder at the application site.
• Known allergy, hypersensitivity, or previous adverse reaction to any component of the investigational cream or placebo.
• Concomitant use of analgesic, anti-inflammatory, or topical treatments on the foot that may interfere with efficacy assessment, unless a washout period is established.
• Recent infiltrations, surgery, or invasive treatment on the foot or ankle that may alter pain evolution during the study.
• Pregnancy or breastfeeding.