This multicenter, randomized, double-blind, placebo-controlled study will evaluate whether an oral supplement containing 2-Aticyto Complex and D-ribose (FibroThol), added to ongoing standard medical treatment, improves pain, symptoms, and clinical course in adults with fibromyalgia syndrome. Eligible participants are adults aged 18 to 65 years who have had fibromyalgia for at least 1 year and have been receiving pregabalin and/or duloxetine for at least 3 months. Participants will be randomly assigned to receive either FibroThol or placebo, administered as 15 mL three times daily for 4 weeks, while continuing their existing treatment. Follow-up assessments will be performed at baseline, week 2, and week 4 using patient-reported symptom and function measures. The study aims to determine whether this supportive supplement provides additional benefit compared with placebo in patients with persistent symptoms despite standard therapy.

Fibromyalgia syndrome is a chronic condition associated with widespread pain, fatigue, sleep disturbance, and reduced quality of life. Although standard pharmacologic treatments such as pregabalin and duloxetine are commonly used, symptom control may remain incomplete in many patients. This study was designed to investigate whether adding a supplement containing 2-Aticyto Complex and D-ribose to ongoing standard treatment can improve clinical outcomes in adults with fibromyalgia syndrome.

This is a multicenter, randomized, double-blind, placebo-controlled clinical study. Adults aged 18 to 65 years with fibromyalgia syndrome, diagnosed according to the ACR 2016 criteria, followed for at least 1 year, and receiving pregabalin and/or duloxetine treatment for at least 3 months will be eligible for participation. Major exclusion criteria include rheumatologic disease, renal failure, hepatic failure, cardiovascular disease, diabetes or hypoglycemia, neurologic disease, use of other supplements, allergy to study product ingredients, inability to complete study procedures, or refusal to participate.

After eligibility assessment and informed consent, participants will be randomly assigned to one of two study groups: placebo plus ongoing standard treatment or FibroThol plus ongoing standard treatment. The study treatment will be administered orally at a dose of 15 mL three times daily for 4 weeks. Study visits and assessments will be performed at baseline, week 2, and week 4.

Outcome measures will include pain intensity, neuropathic pain, fibromyalgia-related functional status, fatigue, sleep quality, anxiety, and depression, assessed using validated clinical scales. Safety will be evaluated through adverse event monitoring during the study period.

A total of 200 participants will be enrolled, with 100 participants assigned to the FibroThol group and 100 participants assigned to the placebo group. The primary objective is to determine whether the addition of 2-Aticyto Complex and D-ribose to standard treatment provides additional benefit in reducing pain and improving symptoms and overall clinical course in patients with fibromyalgia syndrome.

Inclusion Criteria:

• Adults aged 18 to 65 years
• Diagnosis of fibromyalgia syndrome according to the 2016 ACR criteria
• Followed in a physical medicine and rehabilitation outpatient clinic for at least 1 year
• Receiving pregabalin and/or duloxetine treatment for at least 3 months
• Able to live independently in the community
• Literate and able to record symptoms and responses
• No cognitive dysfunction that would interfere with answering study questions
• Able and willing to provide informed consent

Exclusion Criteria:

• Rheumatologic disease
• Renal failure
• Hepatic failure
• Cardiovascular disease
• Hypoglycemia or diabetes mellitus
• Any neurologic disease (such as stroke, spinal cord injury, multiple sclerosis, or Parkinson's disease)
• Known allergy or hypersensitivity to any active or excipient component of the study syrup
• Use of any other dietary supplement or nutritional support product during the study period
• Pregnancy or lactation
• Active malignancy
• Active infection
• Severe psychiatric disease that may interfere with study participation or assessment
• Refusal to participate or inability to provide informed consent

Individual participant data will not be shared. Aggregate results will be reported in publications and trial registry updates.

Participants and investigators will remain blinded to treatment assignment throughout the study. Active treatment and placebo will be provided in similar packaging and appearance to preserve blinding.