The goal of this clinical study is to find out whether using ketoconazole 2% shampoo for seven days works better than using it for three days in treating pityriasis versicolor. The study will also evaluate the safety of both treatment durations.

The main questions this study aims to answer are:

• Does treatment with ketoconazole 2% shampoo for seven days result in better mycological efficacy compared with three days of treatment in patients with pityriasis versicolor?
• Does treatment with ketoconazole 2% shampoo for seven days lead to better clinical improvement compared with three days of treatment?
• Are there differences in side effects between the seven-day and three-day ketoconazole 2% shampoo treatment regimens?
• Are there differences in dermoscopic features of pityriasis versicolor before and after treatment with ketoconazole 2% shampoo when used for seven days compared with three days?

This study is a double-blind randomized clinical trial designed to compare the effectiveness and safety of two different treatment durations of ketoconazole 2% shampoo in patients with pityriasis versicolor, a common superficial fungal infection caused by Malassezia species, particularly prevalent in tropical climates.

The study is conducted in outpatient dermatology clinics in Indonesia, where high temperature and humidity may contribute to persistent or suboptimal treatment responses with standard short-course topical therapy. Current clinical practice commonly recommends a three-day regimen of ketoconazole 2% shampoo; however, longer exposure may be necessary to achieve adequate antifungal activity under tropical conditions. This trial evaluates whether extending treatment to seven days provides superior therapeutic benefit while maintaining an acceptable safety profile.

Eligible participants with a confirmed diagnosis of pityriasis versicolor are randomly assigned to receive ketoconazole 2% shampoo for either three consecutive days or seven consecutive days. Randomization is performed using a concealed allocation sequence. Both participants and investigators are blinded to treatment allocation. The shampoo formulation, packaging, and labeling are identical in both groups to maintain blinding throughout the study.

Participants are instructed to apply the shampoo to affected areas or the entire body, as indicated, once daily according to the assigned regimen. The shampoo is left on the skin for a standardized duration before rinsing. No additional antifungal treatments are permitted during the study period.

Clinical and mycological evaluations are performed at baseline and during follow-up visits. Mycological assessment is conducted using direct microscopic examination of skin scrapings. Clinical evaluation includes physical examination of skin lesions and documentation of treatment response. Dermoscopic examination is performed as supportive data to assess morphological changes before and after therapy.

Safety monitoring is conducted throughout the study. Participants are instructed to report any adverse skin reactions, including irritation, burning sensation, pruritus, or signs suggestive of contact dermatitis. All adverse events are recorded and managed according to predefined safety procedures.

Inclusion Criteria:

• Male and female patients aged 12 years or older
• Patients with pityriasis versicolor confirmed mycologically by the presence of short hyphae and round spores on direct microscopic examination using potassium hydroxide (KOH) preparation and Parker Blue-Black® ink
• Patients who are willing to participate in the study and provide written informed consent after receiving adequate explanation of the study; informed assent is obtained for participants younger than 18 years
• Participants younger than 18 years who have written permission from a parent or legal guardian

Exclusion Criteria:

• Patients in an immobilized condition
• Patients with pityriasis versicolor lesions limited exclusively to the face, without involvement of other body areas
• History of hypersensitivity to ketoconazole
• Use of systemic antifungal agents or systemic corticosteroids within one month prior to study enrollment
• Use of topical antifungal agents or topical corticosteroids within two weeks prior to study enrollment
• Patients with severe immunosuppression
• Pregnant or breastfeeding women

Individual participant data (IPD) will not be shared with other researchers. All data collected in this study will be used solely for the purposes of the study protocol and related publications, and will be reported only in aggregate form to protect participant confidentiality.

Participants, care providers, investigators, and outcome assessors are blinded to treatment allocation. Both study groups receive identically packaged shampoos. In the three-day group, ketoconazole 2% shampoo is administered for three days followed by a placebo shampoo for four days, while the seven-day group receives ketoconazole 2% shampoo for seven days. Blinding is maintained throughout the study.