This randomized, open-label, single-centre controlled study evaluates the efficacy and safety of combined paracetamol and ibuprofen therapy with versus without famotidine in the treatment of calcific tendinitis of the shoulder. Outcomes include pain reduction, functional improvement, radiological changes, and need for additional interventions over a 12-month follow-up period.

Calcific tendinitis of the shoulder is a common cause of acute and chronic shoulder pain, often requiring multimodal treatment. Nonsteroidal anti-inflammatory drugs (NSAIDs) and analgesics such as paracetamol are frequently used as first-line therapy; however, gastrointestinal adverse effects remain a concern. Famotidine, a histamine H2 receptor antagonist, may improve gastrointestinal safety and potentially influence treatment tolerability.

This study is a randomized, open-label, single-centre controlled trial conducted in the emergency surgical outpatient setting. The objective is to compare the efficacy and safety of alternating paracetamol and ibuprofen therapy with the addition of famotidine versus the same analgesic regimen without famotidine in patients with calcific tendinitis of the shoulder.

Participants will be randomized into two groups:

Intervention group: alternating paracetamol (1000 mg) and ibuprofen (400 mg) for 14 days with famotidine 40 mg once daily Control group: paracetamol (1000 mg) and ibuprofen (400 mg) administered concomitantly for 14 days without famotidine Patients on chronic pantoprazole therapy will temporarily switch to famotidine during the intervention period.

The primary outcome is the change in pain and shoulder function measured by the Oxford Shoulder Score (OSS) over 12 months. Secondary outcomes include radiographic changes in calcifications, frequency of additional therapeutic interventions (physical therapy, extracorporeal shockwave therapy, corticosteroid injections, barbotage, and arthroscopic surgery), and treatment safety and tolerability.

Patients will be followed at 2 weeks, 6 weeks, 3 months, and 12 months. Assessments include Visual Analog Scale (VAS), OSS questionnaires, range of motion, and radiographic evaluation at 3 months. Adverse events will be monitored throughout the study.

Inclusion Criteria:

• Age ≥18 years
• Clinical history of shoulder pain consistent with calcific tendinitis
• Presence of calcifications confirmed by shoulder X-ray
• Ability and willingness to comply with study procedures and follow-up
• Signed informed consent

Exclusion Criteria:

• Known allergy or hypersensitivity to paracetamol, ibuprofen, or famotidine
• Active gastrointestinal disease contraindicating NSAID use
• Chronic dual antiplatelet therapy
• Current use of proton pump inhibitors other than pantoprazole (unless temporarily replaced)
• Severe systemic diseases that may interfere with study participation or outcomes