This study will evaluate whether pentoxifylline, when used as an add-on treatment to standard topical therapy, is effective and safe for adults with mild-to-moderate plaque psoriasis. Participants will be randomly assigned to receive either pentoxifylline or placebo twice daily for 12 weeks, while continuing their standard topical treatment. The study will compare improvement in psoriasis severity, itch, physician assessment, quality of life, and adverse events between the two groups. Participants will be followed for a total of 16 weeks.

Psoriasis is a chronic inflammatory skin disease that may cause persistent plaques, itching, and impaired quality of life. Many patients with mild-to-moderate plaque psoriasis are treated mainly with topical therapy, but some patients have an inadequate response or ongoing symptoms. Pentoxifylline is an oral methylxanthine derivative with anti-inflammatory and microcirculatory effects, including inhibition of pro-inflammatory cytokines such as TNF-alpha, IL-1, and IL-6. These mechanisms may be relevant to the inflammatory pathways involved in psoriasis.

This study is a prospective, randomized, double-blind, placebo-controlled, parallel-group trial designed to evaluate pentoxifylline as an add-on therapy to standard topical treatment in adults with mild-to-moderate plaque psoriasis. Eligible participants will be randomly assigned in a 1:1 ratio to receive either pentoxifylline add-on therapy or placebo add-on therapy. All participants will continue standard topical treatment according to usual clinical care.

The treatment period will be 12 weeks, followed by an additional follow-up period until week 16. Clinical assessments will be performed at baseline and follow-up visits to evaluate psoriasis severity, body surface area involvement, physician global assessment, itch severity, quality of life, and safety. The primary objective is to compare the proportion of participants achieving PASI 50 at week 12 between the pentoxifylline and placebo groups. Safety will be assessed by monitoring adverse events, serious adverse events, and laboratory parameters.

Inclusion Criteria:

• Adults aged 18 to 65 years.
• Clinical diagnosis of mild-to-moderate plaque psoriasis, defined as Psoriasis Area and Severity Index (PASI) score 3 to 10 or body surface area (BSA) involvement 3% to 10%, as assessed by a physician.
• Receiving stable standard topical therapy for at least 2 weeks before enrollment.
• Able and willing to provide written informed consent.
• Willing to comply with the study protocol and scheduled follow-up visits.

Exclusion Criteria:

• Use of biologic agents within 12 weeks before enrollment.
• Psoriatic arthritis requiring systemic therapy.
• Pregnant or breastfeeding.
• Severe liver disease or severe kidney disease.
• History of significant bleeding disorder or current use of anticoagulant therapy that cannot be appropriately managed.
• Known hypersensitivity to pentoxifylline or related xanthine derivatives.
• Any serious medical condition or safety concern that, in the investigator's judgment, makes participation inappropriate.
• Refusal or inability to provide informed consent

Individual participant data (IPD) will not be shared because the dataset contains sensitive health information and the study sample size is small, making de-identification difficult. In addition, the informed consent form does not include permission for public sharing of individual-level data.

Participants, investigators, care providers, and outcome assessors will be masked to treatment assignment. Pentoxifylline and placebo will be prepared in identical capsules and dispensed using coded study drug packages. The allocation code will be kept confidential and will not be revealed until completion of the study, unless unblinding is required for participant safety.